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ATJ 35/2018 JKR 20400-0222-19
GEOMETRIC GUIDELINE FOR EXCLUSIVE MOTORCYCLE LANE
Ketua Pengarah Kerja Raya Jabatan Kerja Raya Malaysia Jalan Sultan Salahuddin 50582 Kuala Lumpur
KERAJAAN MALAYSIA
AT
J 35/2018 G
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Jabatan Kerja Raya Cawangan Jalan
©2017 Jabatan Kerja Raya Malaysia. Hak Cipta Terpelihara.
Tidak dibenarkan mengeluarkan mana-mana bahagian artikel, ilustrasi dan
isi kandungan buku ini dalam apa jua bentuk dan dengan apa jua cara sama ada secara elektronik, mekanikal, salinan, rakaman atau cara lain sebelum
mendapat keizinan bertulis daripada penerbit.
Geometric Guideline for Exclusive Motorcycle Lane
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FOREWORD
The Arahan Teknik (Jalan) 35/2018 ‘Geometric Guideline for Exclusive Motorcycle Lane’
is prepared to assist road designers on the design criteria and approach as to provide uniform and standard design for the exclusive motorcycle lanes (EML). With the ever increasing numbers of motorcycles on roads, it has become imperative that motorcycles being given special consideration and provision of exclusive lanes for the safety of the riders and pillions. This document being developed with reference to other Jabatan Kerja Raya’s (JKR)
guidelines, current practices and experiences by stakeholders involving federal government agencies and local authorities. The use of this document shall be read together with the following guidelines;
- NTJ 33/2015 Guidelines For Motorcycle Facilities - ATJ 8/86 (Pindaan 2015): A Guide on Geometric Design of Roads - REAM GL 9/2006: Guidelines on Design and Selection of Longitudinal Traffic
Safety Barrier - Arahan Teknik (Jalan) 15/97 – Intermediate Guideline to Drainage Design of Roads - REAM-GL 8/2004: Guidelines on Traffic Control and Management Devices Part 4
: Pavement Marking and Delineation and Standard Specification for Road Works sub section 6.3: Road Marking
- Arahan Teknik (Jalan) 2A, 2B, 2C and 2E – Manual on Traffic Control Devices - JKR Malaysia Manual Fasiliti Keselamatan Jalan (2014)
The preparation of this guideline was initiated in January 2014 by a committee consisting of members in the relevant expertise areas. It was further deliberated in a special workshop in November 2015 to enhance the guideline’s contents. This guideline is under the purview of Bahagian Inovasi & Standard, Pakar Kejuruteraan Jalan & Jambatan, Cawangan Jalan JKR Malaysia. It will be reviewed and updated from time to time to cater for and incorporate the latest development in road geometric design, as and when necessary. Comments and feedbacks for improvements can be forwarded to the aforementioned office. Published by:
Cawangan Jalan Ibu Pejabat Jabatan Kerja Raya Malaysia Tingkat 21, Menara PJD No. 50, Jalan Tun Razak 50400 Kuala Lumpur Email: [email protected]
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ACKNOWLEDGEMENT
This ATJ 35/2018 was prepared by a working committee comprised of the following members: -
Ir. Razhiah binti Wahab (Chairman) JKR
Ir. Abd Rahman bin Baharuddin JKR
Ir. Dr. Muhammad Marizwan bin Abd Manan MIROS
Pn. Sujatiah binti Tamrin JKR
Ir. Syaharidanisman bin Mohd Johanis JKR
Ir. Fatimah Nuri binti Mohd Yusof JKR
En. Mohd Syukri bin Md Hanafiah JKR
En. Ad. Johan bin Abdullah JKR
En. Ramli bin Ishak JKR
Pn. Atikah binti Md. Radzi JKR
En. Afiq Haffifi bin Abdullah JKR
En. Mohd Hafizee bin Haron JKR
En. Asward Indra Firhad bin Abdul Aziz JKR
Pn. Noorel Syema binti Yatim Ishak JKR
Special recognition to Associate Prof. Dr. Hussain bin Hamid from UPM and Puan Norfaizah binti Mohamad Khaidir from MIROS who have contributed significantly on the literature of motorcycle lane capacity and egress / ingress issues respectively.
Last but not least, our utmost appreciation also goes to YBrs. Ir. Hj. Zulakmal bin Hj. Sufian, Senior Director of Cawangan Jalan, and YBhg. Dato’ Ir. Che Noor Azeman bin Yusoff, Director of Pakar Kejuruteraan Jalan & Jambatan, Cawangan Jalan, Jabatan Kerja Raya Malaysia for their undivided support and cooperation given towards the successful completion of this guideline.
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LIST OF CONTENTS
Page
FOREWORD i
ACKNOWLEDGEMENT ii
1.0 INTRODUCTION 1
1.1 Purpose 1
1.2 Scope of Guideline 1
2.0 MOTORCYCLE LANE CLASSIFICATION AND DESIGN STANDARDS 2
2.1 Motorcycle Lane Classification / Hierarchy 2
2.2 Design Standards for Motorcycle Lane 2
2.2.1 Importance of Standardization 2
2.2.2 Warrant for Motorcycle Lane 3
2.3 Access Control 4
3.0 DESIGN CONTROL AND CRITERIA 5
3.1 Motorcycle Characteristics 5
3.2 Speed 9
3.2.1 Speed 9
3.2.2 Design Speed 10
3.3 Capacity 13
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LIST OF CONTENTS
Page
4.0 ELEMENT OF DESIGN 17
4.1 Sight Distance 17
4.1.1 General 17
4.1.2 Stopping Sight Distance for Motorcycle Rider 17
4.1.3 Decision Sight Distance for Riders, DSDMC 20
4.1.4 Passing Sight Distance 22
4.1.5 Criteria for Measuring Sight Distance 22
4.2 Horizontal Alignment 23
4.2.1 General 23
4.2.2 Superelevation Rates 23
4.2.3 Minimum Radius 23
4.2.4 Design Superelevation Tables 25
4.2.5 Transition Design Control 26
4.2.6 Method of Attaining Superelevation 31
4.2.7 Sight Distance on Horizontal Curve 33
4.2.8 General Controls for Horizontal Alignment of the EML 33
4.3 Vertical Alignment 35
4.3.1 General Considerations 35
4.3.2 Crest Vertical Curves 36
4.3.3 Sag Vertical Curves 37
4.3.4 General Controls for Vertical Alignment 39
4.4 Combination of Horizontal and Vertical Alignment 41
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LIST OF CONTENTS
Page
5.0 CROSS SECTION ELEMENTS 42
5.1 Pavement 42
5.1.1 Surface Type 42
5.1.2 Design Standard 43
5.1.2.1 Flexible Pavement 43
5.1.2.2 Rigid Pavement 44
5.1.2.3 Normal Cross Slope 45
5.2 Lane Width & Marginal Strips for Motorcycle Lane 45
5.3 Shoulders 46
5.3.1 General Characteristics 46
5.4 Traffic Barriers 50
5.4.1 General 50
5.4.2 Traffic Barriers for Motorcycle Lane 50
5.4.2.1 Method 1: Additional Rub Rail 50
5.4.2.2 Method 2: Special Impact Attenuators 52
5.5 Underpass 54
5.5.1 Required Clearance 54
6.0 TREATMENTS FOR SPECIAL CONDITIONS 56
6.1 Treatment of EML Approaching Egress and Ingress 56
6.2 Treatment of EML Approaching Pedestrian Crossing 59
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LIST OF CONTENTS
Page
7.0 OTHER ELEMENTS AFFECTING GEOMETRIC DESIGN 60
7.1 Drainage 60
7.1.1 Gutter Drain 63
7.2 Lighting 65
7.3 Utilities 67
7.4 Signages and Markings 67
7.4.1 Road Markings 67
7.4.2 Traffic Signs 67
7.5 Erosion Control, Landscape Development and Environmental Impacts 69
REFERENCES 70
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1.0 INTRODUCTION
1.1 Purpose
Malaysia, as part of ASEAN has high percentage of motorcycles in the transport models. In normal road design practice, all vehicle types share the same carriageway travelling from one destination to another. With the high number of motorcycles, the likelihood for fatal accident to occur involving motorcyclists is greater.
Separating motorcycles from other vehicles in traffic by providing motorcycle lanes is a good engineering measure to improve the safety of motorcyclists. There are non-exclusive motorcycles lanes (NEML) and exclusive motorcycles lanes (EML) provided at certain road stretches in Malaysia. However, there has been no established guideline for the design of motorcycle lanes. The lanes, either on Expressways or Non-expressways are constructed based on the respective authorities’ own documents
which differ from one to the other.
The purpose of this new guideline is to provide road designers in Malaysia with a uniform and standard design for the construction of EML. It is to be applied to all new road construction and improvements which fulfil the warrant for motorcycle lane facility. Hence this guideline is to be used in conjunction with other guidelines that have been or will be produced by JKR.
1.2 Scope of Guideline
The scopes covered under this guideline are as follows:
i. Motorcycle Lane Classification and Design Standards ii. Design Control and Criteria iii. Element of Design iv. Cross Section Elements v. Treatments for Special Conditions vi. Other Elements Affecting Geometric Design
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2.0 MOTORCYCLE LANE CLASSIFICATION AND DESIGN STANDARDS
2.1 Motorcycle Lane Classification / Hierarchy
It is important to define a hierarchy of motorcycle lane so that the road authority is able to systematically plan and develop their network to meet the needs for local access, cross town/city travel, intra-state and inter-state travel. Furthermore specific planning criteria could be developed and applied according to this road hierarchy.
There are two (2) types of facilities for motorcycle lane:
a) Exclusive Motorcycle Lane i) Roadway meant exclusively for use by motorcycles (motorcyclists are
compelled by law to use it and other vehicles are prohibited by law from using it);
ii) Physically separated from main carriageway; and iii) Grade separated from the main carriageway at intersections/interchanges/
points of conflicts. b) Non-exclusive Motorcycle Lane
i) Extra lane/verge/marginal strip on the left hand side of the road.
The exclusive motorcycle lanes are to be provided in two (2) categories of roads which are Expressway and Non-expressway.
Expressway is characterized by high speed high volume road with full access control and grade separated interchanges all along the road. While Non-expressway defined as roads other than expressways and include Federal Roads, State Roads, Municipal Roads and other roads.
2.2 Design Standards for Motorcycle Lane
2.2.1 Importance of Standardization
Technically, the geometric design of EML need to be standardized for the following reasons:
a) To provide uniformity in the design of EML according to their performance requirements;
b) To provide consistent, safe and reliable EML; and c) To provide a guide for less subjective decision on EML design.
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2.2.2 Warrant for Motorcycle Lane
The warrant for motorcycle lane depends on total volume of traffic, percentage of motorcycles and total number of motorcycle accidents. Refer TABLE 2.1 for details.
TABLE 2.1: SUMMARY OF WARRANT ANALYSIS FOR EXCLUSIVE MOTORCYCLE LANE
Numerical Warrants
Type of Roads
Expressways Non
Expressways
Section of
Expressways and
Non Expressways
1. Total Volume of Traffic
> 15,000 vehicle per day
> 15,000 vehicle per day along a
2-lane 2-way road
OR
> 10,000 vehicle per day per lane
along a multi-lane road
• For Section with Expressway Road Conditions, Warrant for Expressways shall apply.
OR
• For Section with Non Expressway Road Conditions, Warrant for Non Expressways shall apply.
OR
• For combination of Expressway and Non Expressways along the road, the engineer’s
experience and engineering judgment is required to decide the most appropriate form of motorcycle facilities.
2. Percentage of Motorcycles
> 30% of main stream traffic
> 30% of main stream traffic
3. Total Number of Motorcycle Accidents
> 5 accidents per km per year
> 5 accidents per km per year
4. Side Friction Scores Not applicable
< 30 friction
scores
5. Combination of 1,2,3 and/or 4
• Can be provided even if not fulfilling criteria 1, 2, 3 or 4 if its absence would be detrimental to the safety of motorist/other road user.
• Warrants if there is a high likelihood of warrants 1, 2, 3 and/or 4 being met within 5 years of design life of the project.
Source: NTJ 33/2015 Guidelines for Motorcycle Facilities
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2.3 Access Control
Access control is the condition where the right of owners or occupants of abutting land or other persons to access, in connection with a road is fully or partially controlled by the public authority. Access control is classified into three (3) types for its degree of control, namely full control, partial control and non-control access.
EML shall be designed with full access control to improve safety of the road users and to increase efficiency of the traffic function, while acknowledging the needs and amenable use of adjacent land, through the provision of safe and appropriate access.
Full Access Control means that preference is given to through traffic by providing access connection with selected public roads only and prohibiting at-grade crossings or direct private driveway connections. The access connections with public roads vary in the spacing between them from 2 km in the highly developed central business areas to 8 km or more in the sparsely developed urban fringes.
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3.0 DESIGN CONTROL AND CRITERIA
This chapter discusses the characteristics that govern the various elements in the design of motorcycle lane which includes motorcycle characteristics, design speed of the lane and the capacity to be provided along the motorcycle lane.
3.1 Motorcycle Characteristics
The geometric design of motorcycle lane is affected by the physical characteristics and the proportion of various sizes of motorcycle. For purposes of geometric design, the design motorcycle should be one with dimensions and minimum turning radius larger than those of almost all motorcycles in its class. Therefore, motorcycles with capacity of 250cc and below only are considered to be used in this geometric guideline.
TABLE 3.1 below summarizes the motorcycle dimensions and characteristics.
TABLE 3.1: MOTORCYCLE DIMENSIONS
Motorcycle
Description
Dimension in Metres (Maximum) Turning
Radius
(Metres) Length Width Height
Motorcycle ≤ 250 cc
2.60 1.00 1.64
(inclusive of rider)
3.00
The motorcycle type to be used for geometric design follows that used by NTJ 33/2015 Guidelines for Motorcycle Facilities.
FIGURES 3.1, 3.2, 3.3, 3.4 and 3.5 show the dimensions and turning characteristics for the 250cc and below motorcycle.
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FIGURE 3.1: TYPICAL DIMENSION OF A MOTORCYCLE ≤ 150cc (SIDE VIEW)
FIGURE 3.2: TYPICAL DIMENSION OF A MOTORCYCLE ≤ 150cc (FRONT VIEW)
Length 2.0 m
mm
Width 0.8 m
Height 1.56 m
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FIGURE 3.3: TYPICAL DIMENSION OF A MOTORCYCLE ≤ 250 cc (SIDE VIEW)
FIGURE 3.4: DIMENSION OF A MOTORCYCLE ≤ 250 cc (FRONT VIEW)
1000 mm
Length 2.60 m
mmmm
Width 1.0 m
Height 1.635 m
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FIGURE 3.5: DESIGN OF MOTORCYCLE – TURNING RADIUS (MAXIMUM – 250 cc)
2.60 m
1400mm
3.0 m min.
3.0 m Minimum Turning Radius
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3.2 Speed
3.2.1 Speed
Speed of travel is an important factor in all modes of transportation. Speed determines the travel duration and expected time of arrival at a particular destination. Generally, standard of road and associated roadway elements are some of the influencing factors on the desired driving speed of road users.
Any route can be traversed at a certain maximum safe speed which is usually attributed to the road geometric features. A new road is designed based on a certain road standard with a predefined design speed that conforms to the terrain surface condition. However, the traffic population and surrounding development may restrict the range of speed that can be safely traversed by road users. The appropriate operational speed also ensures that comfort and safety aspects of the road users are being taken care of.
A vehicle can be driven or ridden within a certain range of speed, subject to the inherent level of its mechanical operating capacity. High capacity motorcycles (e.g. 250 cc and above) can easily accelerate from zero to 60 kph within a few seconds and capable of traveling at very high speed. At high speed, a motorcycle tends to be more vertically stable however its agility and maneuverability drops. In the event of an emergency, such as a sudden obstruction in its path due to some accident ahead, motorcyclists traveling at high speed may not be able to make a drastic change in direction or reduce their speed significantly without risking of losing their balance. There are very specific limits to how sharp or fast we can turn and how these are related to the size and design of the bike. Frequently, riders may lose control of their vehicles and usually end up falling off their motorcycles or crashes into the obstruction or ends up with serious consequences or even death.
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3.2.2 Design Speed
Speed is one of the main components for geometric control. In establishing standard geometric design elements for the motorcycle laneway, it is decided that instead of having a range of standards similar to that for normal roadway, a selected single design speed is proposed for the design of motorcycle lane geometric irrespective of the terrain condition.
High speed travel requires road with high geometric standard with very generous alignment features. Large road curvatures and wide cross sectional elements are associated with such high standard. Based on experiences gained in the construction of existing exclusive motorcycle lane, section of the lane that is geometrically constrained is usually at interchanges. The alignment which meanders through underpasses may consist of multiple curves with short length of straights. Generally, the selected design speed must also be suitable with such geometric constraints, otherwise a lower speed limit may have to be specified for the particular section of the alignment.
FIGURE 3.6: AN EXAMPLE MEANDERING ALIGNMENT BEFORE ENTERING UNDERPASS
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In deciding the appropriate design speed, one must understand some of the limits and constraints thereafter. Practically, existing terrain features, limited space and land use are some of the constraints that may limit the standard of road possible. Limitations of rider handling capability and vehicle operating capacity shall be considered accordingly. Notwithstanding the above, there are current facts and figures that need consideration of some guidance on the proposed design speed:
a. It was found that 99% of the motorcycles population in Malaysia comprises those of small and medium-sized type motorcycles with engine sizes 150 c.c. and below. Because of their small size, a rider does not require much space for maneuvering.
b. The proposed group of motorcyclists that is required to use the exclusive motorcycle lane are those riding motorcycles with a capacity of 250 cc or below. Based on the survey conducted by MIROS, the maximum speed of travel is not more than 140 kph. However, the appropriate design speed shall be lower than the maximum.
c. Motorcyclists, like pedestrians, are equally vulnerable in the case of road casualty. The poor protective nature of motorcyclists warrants serious considerations be given to the safety of the motorcycle rider/pillion. The risk of accident must be kept at the lowest level possible simply because, in the event of an accident, motorcyclists are very susceptible to serious injury or death. Hence there must be some limit to the maximum speed of travel along the motorcycle lane. At an impact of 60 kph, a pedestrian or motorcyclist, for that matter, has little chance of surviving a crash – at an impact speed of 40 kph the chance of survival for pedestrian is about 80 percent.
d. A spot speed study along the exclusive motorcycle lane along FT002
found that motorcyclists can reach up to a speed of more than 100 kph on certain section of the route even though the design speed for the facility was set at 60 kph then. This indicated that motorcyclists can confidently travel at higher speeds along the exclusive motorcycle lane but generally confined to a less meandering section of the alignment. Observations also showed that at high speed they would be travelling in a single file much due to safety reasons.
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FIGURE 3.7: CUMULATIVE FREQUENCY DISTRIBUTION OF SPEED OF MOTORCYCLES TRAVELING ON THE EXCLUSIVE MOTORCYCLE LANE ALONG FT002
Taking into consideration of the factors mentioned above including safety and vulnerability of motorcyclist, it is proposed that a range of design speed 50 kph to 90 kph to be used in the design of EML. Where there are physical constraints, this design speed may be lowered. This design speed shall also be the guiding reference in determining other physical elements of the motorcycle. This includes the required sight distance to facilitate safe stopping at some critical areas such as junctions and underpasses.
TABLE 3.2: MOTORCYCLE PERCENTAGE DISTRIBUTION IN MALAYSIA BY
CAPACITY
Capacity of Motorcycle
(cc) < 90 91 – 110 111 – 125 126 – 150 151 – 250 251 – 500 501 – 1000 > 1000
% of Registered Motorcycle
1.7 40.0 33.5 18.9 3.6 0.2 1.7 0.5
Max Speed (kph) 80 89 97 105 137 217 378 443
*Note: Maximum speed is calculated based on the engine capacity of the motorcycle Source: JPJ 2012
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3.3 Capacity
A study by Hussain et al. (2005) on motorcycle/rider characteristic reported that small and medium-sized motorcycles (less than 150 c.c. engine) represented 99% of all motorcycles in Malaysia. The static handlebar width of a motorcycle/rider unit is 0.8 m while the operating width ranged from 0.9 m to 1.7 m (a mean width of 1.3 m). There are two observable behaviour patterns with regards to motorcyclists riding manner which are influenced by the width of the motorcycle lane. The first pattern is for situations when the motorcycle lane width is 1.7 m or less thus constraining the available riding space of the motorcyclists and as a consequent, forcing them to ride in a single file regardless of low or high flow traffic conditions. This riding behaviour is to be known as headway (or platoon) behaviour and the motorcycle flow is measured in mc/h/ln. For the second riding pattern, motorcyclists are able to pass another motorcyclist within the motorcycle lane as the width is more than 1.7 m. The formation of two lines during low or high flow traffic conditions is observable and this pattern is referred to as the space pattern and the motorcycle flow is expressed in mc/h/m-width.
In another related study, Hussain et al. (2011) established that the shape of the motorcycle speed-density relationships for an uninterrupted exclusive motorcycle lane for both types of observable motorcycle riding behaviour (i.e. the headway or platoon pattern and space pattern) takes the form of a logarithmic curve. Further, based on the fundamental theory that flow is a product of speed and density, the motorcycle flow-density and motorcycle speed-flow relationships were mathematically derived. The three fundamental motorcycle speed-flow-density relationships exhibited trends similar to the ones established for the pedestrians, bicycles and automobiles which followed the theory of flow.
From the motorcycle flow-density curves, it was determined that under the headway riding pattern (lane width of 1.4 m to 1.7 m) capacity is reached at a maximum motorcycle flow of 3060 mc/h/lane corresponding to a critical density of 235 mc/km/lane as shown in FIGURE 3.8. While under the space riding pattern (lane width >1.7 m) capacity occurs at a maximum motorcycle flow of 2207 mc/h/m which corresponds to a critical motorcycle density of 0.166 mc/m2 (or space of 6.0 m2/mc) as shown in FIGURE 3.9.
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FIGURE 3.8: MOTORCYCLE FLOW AND MOTORCYCLE DENSITY CURVE
(HEADWAY RIDING PATTERN)
FIGURE 3.9: MOTORCYCLE FLOW AND MOTORCYCLE DENSITY CURVE
(SPACE RIDING PATTERN) By examining the motorcycle speed-flow-density models for the headway and the space concepts, the critical motorcycles speed, flow and density parameters were determined and summarized TABLE 3.3.
TABLE 3.3: VALUES OF PARAMETERS AT CAPACITY CONDITIONS FOR MOTORCYCLE FACILITY
Parameter Headway Concept
(1.4m ≤ W ≤ 1.7m)
Space Concept
(1.7m < W ≤ 3.3m)
Critical Density 235 mc/km/ln 0.166 mc/m2
Critical Speed 13 kph 13 kph
Maximum Flow Rate 3060 mc/h/ln 2207 mc/h/m
Source: Hussain H., Radin Umar R.S., Ahmad Farhan M.S., 2011. Establishing Speed Flow-Density Relationships for Exclusive Motorcycle Lanes
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Practically, a 1.4 m to 1.7 m wide motorcycle lane is capable of carrying a maximum motorcycle flow of 3060 mc/h. By doubling the lane widths would mean that a 2.8 m to 3.4 m wide motorcycle lane is capable of carrying 6120 mc/h as if the motorcyclists are riding in two single-files across the width of motorcycle lanes. In the case of space riding pattern which has a capacity of 2207 mc/h per metre width, a motorcycle lane of 2.0 m wide, for instance is capable of carrying 4414 mc/h. The computed values of maximum flow rate for different motorcycle lane widths are presented in TABLE 3.4 and graphically illustrated in FIGURE 3.10. Note that it is limited for uninterrupted exclusive motorcycle lanes not more than 3.4 m wide. The use of the appropriate concept according to the motorcycle lane width would be useful in reducing the implication on the construction costs and the performance of the exclusive motorcycle lane system.
TABLE 3.4: MAXIMUM FLOW RATE FOR VARIOUS MOTORCYCLE LANE WIDTHS
Source: Hussain H. 2006. Development of Capacity and Level-Of-Service for Uninterrupted Exclusive Motorcycle Lanes in Malaysia
Motorcycle
Lane Width
(m)
Headway Concept
c = 3060 mc/h/ln
Space Concept
c = 2207 mc/h/m
Maximum Flow Rate
(mc/h/ln)
Maximum Flow Rate
(mc/h/ln)
1.4 3060 -
1.5 3060 -
1.6 3060 -
1.7 3060 -
1.8 - 3973
1.9 - 4193
2.0 - 4414
2.1 - 4635
2.2 - 4855
2.3 - 5076
2.4 - 5297
2.5 - 5518
2.6 - 5738
2.7 - 5959
2.8 6120 -
2.9 6120 -
3.0 6120 -
3.1 6120 -
3.2 6120 -
3.3 6120 -
3.4 6120 -
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FIGURE 3.10: CHART OF MAXIMUM MOTORCYCLE FLOW RATE FOR MOTORCYCLE LANES OF VARIOUS WIDTHS
Source: Hussain H. 2006. Development of Capacity and Level-Of-Service for Uninterrupted
Exclusive Motorcycle Lanes in Malaysia
0500
1000150020002500300035004000450050005500600065007000
1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4
Motorcycle Lane Width (m)
Ma
xim
um
Mo
torc
yc
le F
low
(mc
/hr/
ln)
05001000150020002500300035004000450050005500600065007000
Ma
xim
um
Mo
torc
yc
le F
low
(mc
/hr/
ln)
Headway HeadwaySpace
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4.0 ELEMENT OF DESIGN
4.1 Sight Distance
4.1.1 General
Sight distance in this document is the length of road ahead visible to a motorcycle rider. The ability of a rider to see ahead is of utmost importance to the safe and efficient operation of a road. The designer must provide sight distance of sufficient length in which riders can control the speed of the motorcycle so as to avoid striking an unexpected obstacle on the travelled way. Also, at frequent intervals and for a substantial portion of the length whereby riders can overtake motorcycles without hazard, the provision of sufficient sight distance is very important.
Sight distance includes stopping sight distance, passing sight distance and decision sight distance.
4.1.2 Stopping Sight Distance for Motorcycle Rider
The stopping sight distance is the length required to enable a rider, travelling at or near the design speed to stop before reaching an object in its path. Minimum stopping sight distance is the sum of two distances, i.e.:
a) Rider’s Perception and Brake Reaction distance: The distance traversed
by a rider from the instant the riders sights an object for which a stop is necessary, to the instant the brakes are applied; and
b) Rider’s Braking Distance: The distance required to stop the motorcycle after the brake is applied.
In order to determine the appropriate stopping sight distance, two important components must be established, i.e. the rider’s perception and brake reaction time (tMC) and motorcycle deceleration rate, in m/s2 (aMC), presented in the next two subsections.
4.1.2.1 Rider’s Perception and Brake Reaction Distance, DMCPRT
For safety, a reaction time that is sufficient for most operators, rather than for the average operator is used in the determination of minimum sight distance. Based on a research by Lenkeit et al. (2011), a perception and brake reaction time for a rider is found to be 2.0 seconds (For passenger car driver, the perception and brake reaction time is 2.5 seconds). TABLE 4.1 shows the DMCPRT corresponding to the design speed, VDS. The formula used is based on the standard formula in AASHTO (2011)(see the formula below), which also applies for motorcycle with the notation of DMCPRT as follows:
𝐷𝑀𝐶𝑃𝑅𝑇 = 0.278 ∙ 𝑉𝐷𝑆 ∙ 𝑡𝑀𝐶
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TABLE 4.1: RIDER’S PERCEPTION AND BRAKE REACTION DISTANCE
(m), DMCPRT = 0.278 x VDS x tMC (Rounded)
Design Speed, VDS Driver Perception / Reaction Distance (m), DMCPRT
90 50 80 44 70 39 60 33 50 28
4.1.2.2 Rider’s Braking Distance, DMCB
The approximate braking distance of a motorcycle on a level roadway is determined by the use of standard formula based on AASHTO (2011), (see the formula below), which also applies for motorcycle with the notation of:
𝐷𝑀𝐶𝐵 = 0.039𝑉𝐷𝑆
2
𝑎𝑀𝐶
TABLE 4.2 shows the DMCB corresponding to the design speed, VDS. As for the value of aMC, research has shown that average vehicle drivers decelerate at a rate greater than 4.5 m/s2 when confronted with the need to stop for an unexpected object in the roadway. Approximately 90 percent of all drivers decelerate at rates greater than 3.4 m/s2 (Fambro et al. 1997). Such decelerations are within the driver’s capability to stay within his or her lane and
maintain steering control during the braking manoeuver on wet surfaces. Therefore, unless a new research is done on the specific capability of motorcycle to decelerate, the value of 3.4 m/s2 (a comfortable deceleration for most drivers) is also recommended as the deceleration (aMC) threshold for determining motorcycle braking distance.
TABLE 4.2: MOTORCYCLE BRAKING DISTANCE (m), DMCB = 0.039 x VDS
2 / aMC (Rounded)
Design Speed,
VDS Braking Distance (m), DMCB
90 93 80 73 70 56 60 41 50 29
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4.1.2.3 Design Value for Minimum Stopping Sight Distance for Riders, SSDMC
The sum of the distance traversed by a rider during perception and brake reaction time, DMCPRT and the distance required to stop the motorcycle DMCB is the minimum stopping sight distance (see formula below based on the standard formula AASHTO (2011). The values to be used for minimum stopping sight distances are as shown in TABLE 4.3.
SSDMC = DMCPRT + DMCB
TABLE 4.3: MINIMUM STOPPING SIGHT DISTANCE (m), SSDMC = DMCPRT + DMCB (ROUNDED)
Design Speed, VDS Min. Stopping Sight Distance, SSDMC (m),
90 150 80 120 70 100 60 80 50 60
4.1.2.4 Effect of Grades on Minimum Stopping Sight Distance for Riders, SSDGMC
When a road is on a grade, the standard formula for the minimum stopping sight distance based on AASHTO (2011) is presented in the formula below, which applies also for motorcycle with the notation of SSDGMC is:
𝑆𝑆𝐷𝐺𝑀𝐶 =𝑉𝐷𝑆
2
254 (𝑎𝑀𝐶9.8 ± 𝑔)
in which g is the percentage of grade divided by 100. The effect of grade on stopping sight distance for riders, SSDMC is as shown in TABLE 4.4.
TABLE 4.4: EFFECTS OF GRADES ON MINIMUM STOPPING SIGHT DISTANCE FOR RIDERS (m), SSDGMC
Design
Speed,
VDS
SSDMC
SSDGMC: Stopping Sight
Distance (m) for Upgrades
SSDGMC: Stopping Sight
Distance (m) for Downgrades
3% 6% 9% -3% -6% -9%
90 150 85 80 75 105 115 125
80 120 70 65 60 80 90 100
70 100 55 50 45 65 70 75
60 80 45 40 35 45 50 55
50 60 26 24 23 31 34 38
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4.1.3 Decision Sight Distance for Riders, DSDMC
Stopping sight distances are usually sufficient to allow reasonably competent and alert riders to come to a hurried stop under ordinary circumstances. However, these distances are often inadequate when riders must make complex or instantaneous decisions, when information is difficult to perceive, or when unexpected or unusual maneuvers are required. Limiting sight distances to those provided for stopping may also prelude riders from performing evasive maneuvers, which are often less hazardous and otherwise preferable to stopping. Even with an appropriate complement of standard traffic control devices, stopping sight distances may not provide sufficient visibility distances for riders to corroborate advance warning and to perform the necessary maneuvers. It is evident that there are many locations where it would be prudent to provide longer sight distances. In these circumstances, decision sight distance provides the greater length that riders need.
Decision sight distance for riders, DSDMC (which used the similar formula in AASHTO (2011)) is the distance required for riders to detect an unexpected object or otherwise difficult-perceived information source or hazard in a roadway environment that may be visually cluttered, recognize the hazard or its potential threat, select an appropriate speed and path, and initiate and complete the required safety manoeuver safely and efficiently. Because DSDMC gives riders additional margin for error and affords them sufficient length to maneuver their motorcycles at the same or reduced speed rather than to just stop, its values are substantially greater than stopping sight distance, SSDMC.
Riders need decision sight distance, DSDMC whenever there is likelihood for error in information reception, decision-making, or control actions. Examples of critical locations where these kinds of errors are likely to occur, and where it is desirable to provide decision sight distance are interchange and access point (egress / ingress) locations where unusual or unexpected maneuvers are required.
The rider’s decision sight distances, DSDMC in TABLE 4.5 provide values to be used by designers for appropriate sight distances at critical locations and serve as criteria in evaluating the suitability of the sight lengths at these locations. Because of the additional safety and maneuverability these lengths yield, it is recommended that DSDMC be provided at critical locations or that these points be relocated to locations where decision sight distances are available. If it is not possible to provide these distances because of horizontal or vertical curvature or if relocation is not possible, special attention should be given to the use of suitable traffic control devices for providing advance warning of the conditions that are likely to be encountered.
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DSDMC values that will be applicable to most situations have been developed from empirical data, based on AASHTO (2006). The decision sight distances vary depending on whether the location of the exclusive motorcycle lane is on a rural or urban road, and on the type of manoeuver required to avoid hazards and negotiate the location properly. TABLE 4.5 shows decision sight distance values for various situations rounded for design. As can be seen in TABLE 4.5, generally shorter distances are required for rural roads and when a stop is the manoeuver involved. The DSDMC values are determined as:-
For Maneuver A and B: 𝐷𝑆𝐷𝑀𝐶_𝐴𝑀 (𝐴 𝑜𝑟 𝐵) = 0.278 ∙ 𝑉𝐷𝑆 ∙ 𝑡𝑀𝐶_𝐴𝑀 (𝐴 𝑜𝑟 𝐵) + 0.039 (
𝑉𝐷𝑆
𝑎𝑀𝐶)
For Maneuver C and D: 𝐷𝑆𝐷𝑀𝐶_𝐴𝑀 (𝐶 𝑜𝑟 𝐷) = 0.278 ∙ 𝑉𝐷𝑆 ∙ 𝑡𝑀𝐶_𝐴𝑀 (𝐶 𝑜𝑟 𝐷)
The following avoidance maneuvers are covered in TABLE 5:
a) Avoidance maneuver A: Stop on rural road: tMC_AM(A) = 2.5 seconds
b) Avoidance maneuver B: Stop on urban road:
tMC_AM(B) = 7.58 seconds c) Avoidance maneuver C: Speed/ path/ direction change on rural road:
tMC_AM(C) = 9.33 seconds d) Avoidance maneuver D: Speed/ path/direction change on urban road:
tMC_AM(D) = 12.08 seconds
The basis of the perception and brake reaction time value (tMC_AM(A,B,C&D)) is derived from the value of the perception and brake reaction time of a passenger car driver, which was reduced proportionally (2.5 s for passenger car driver : 2.0 s for riders) with the assumption that perception and brake reaction time of a rider is much lower than a passenger car driver.
TABLE 4.5: DECISION SIGHT DISTANCE FOR RIDERS, DSDMC, FOR AVOIDANCE MANEUVER (ROUNDED)
Design Speed, VDS
tMC_AM(A)
= 2.5s tMC_AM(B) =
7.58s tMC_AM(C) =
9.33s tMC_AM(D) =
12.08s
90 65 190 235 305
80 60 170 210 270
70 50 150 185 240
60 45 130 160 205
50 35 106 130 169
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4.1.4 Passing Sight Distance
Passing sight distance for riders on an exclusive motorcycle lane is not applicable due to the single carriageway traffic flow configuration.
4.1.5 Criteria for Measuring Sight Distance
4.1.5.1 Height of Rider’s Eye
In computing and measuring motorcycle sight distances, SSDMC or DSDMC, the 1.49 m eye height (average rider’s eye height based on satisfactory sample
size).
4.1.5.2 Height of Object
A height of object of 0.2 m is assumed for measuring stopping sight distance measured from the road surface. Although riders may have to be able to see the entire roadway situation, including the road surface, the rationale for the 0.2 m object height is as applicable for decision as it is for stopping sight distance.
Sight distance should be considered in the preliminary stages of design when both the horizontal and vertical alignments are still subject to adjustment. The sight distance should be determined graphically on the alignment plans and recorded at frequent intervals, for both directions of travel. This will enable the designer to appraise the overall layout and affect a more balanced design by minor adjustments in the plan or profile.
Horizontal sight distance should be measured on the inside of a curve at the center of the inside lane. Vertical sight distance should be measured along the longitudinal profile of the central line, using the height of driver's eye and the object height. FIGURE 4.1 and FIGURE 4.2 in ATJ 8/86 (Pindaan 2015) provide examples of measuring sight distance in both plan and profile respectively.
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4.2 Horizontal Alignment
4.2.1 General
In the design of horizontal curves, it is necessary to establish the proper relationship between the design speed and curvature and also their joint relations with superelevation and side friction. From research and experience, limiting values have been established for the superelevation (e) and the coefficient of friction (f).
4.2.2 Superelevation Rates
The purpose of superelevation or banking of curves is to counteract the centripetal acceleration produced as a vehicle rounds a curve. The maximum rates of superelevation usable are controlled by several factors such as climatic conditions and terrain conditions that would be subjected to uncertain operation.
While it is acknowledged that a range of values should be used, for practical purposes in establishing the design criteria for horizontal alignment, a superelevation rate not exceeding 8% can be used.
4.2.3 Minimum Radius
The minimum radius is a limiting value of curvature for a given speed and is determined from the maximum rate of superelevation and the maximum allowable side friction factor.
The minimum safe radius (Rmin) can be calculated from the standard curve formula based on AASHTO (2011).
𝑅𝑚𝑖𝑛 =𝑉𝐷𝑆
2
127 (𝑒 + 𝑓)
Where,
Rmin = Minimum radius of circular curve (m) VDS = Design Speed (kph) e = Maximum superelevation rate f = Maximum allowable side friction factor based on
AASHTO (2011), see TABLE 4.6.
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TABLE 4.6: MAXIMUM SIDE FRICTION, f
Design Speed,
VDS Maximum Side Friction, f
90 0.13 80 0.14 70 0.14 60 0.15 50 0.16
TABLE 4.7 lists the minimum radius to be used for the designated speeds and maximum superelevation rates with respect to each terrain type. While the values in TABLE 4.7 lists the minimum radius that can be used, it should be noted, that the above minimum radius will not provide the required stopping sight distance within typical cross-sections. Hence, all efforts should be made to design the horizontal curves with radius larger than the minimum values shown for greater comfort and safety.
TABLE 4.7: MINIMUM RADIUS (m) Rmin
Design Speed, VDS Min. Stopping
Sight Distance
Minimum Radius (m),
Rmin (Rounded)
e = 6% e = 8%
90 150 335 305 80 120 250 230 70 100 190 180 60 80 135 125 50 60 90 80
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4.2.4 Design Superelevation Tables
TABLE 4.8A and 4.8B show minimum values of R for various combinations of superelevation and design conditions. When using one of the tables for a given radius, interpolation is not necessary as the superelevation rate should be determined from a radius equal to or slightly smaller than the radius provided in the table. For example, an 80kph curve on an exclusive motorcycle lane with a maximum superelevation rate of 5 percent, the minimum radius is 457 m. The computation of these tables are based on AASHTO (2011).
Under all but extreme weather conditions, motorcycles can travel safely at speeds higher than the design speed on horizontal curves with superelevation rates indicated in the table. This is due to the development of a radius/superelvation relationship that uses friction factors that are generally considerably less than can be achieved.
For an average rate of cross slope of 1.5 percent, the corresponding minimum radius for each design speed and maximum superelevation rate is shown in the top row of TABLE 4.8A and TABLE 4.8B. These are curvatures calling for superelevation equal to the normal cross slope, and therefore indicate the limit of curvature with normal cross slopes. Sharper curves should have no adverse cross slope and should be superelevated in accordance with TABLE 4.8A to 4.8B.
TABLE 4.8A: MINIMUM RADII FOR DESIGN SUPERELEVATION RATES, DESIGN SPEEDS, AND emax = 6%
1.5 194 421 738 1050 1440 1910 2360 2880 3510
2.0 138 299 525 750 1030 1380 1710 2090 2560
2.2 122 265 465 668 919 1230 1530 1880 2300
2.4 109 236 415 599 825 1110 1380 1700 2080
2.6 97 212 372 540 746 1000 1260 1540 1890
2.8 87 190 334 488 676 910 1150 1410 1730
3.0 78 170 300 443 615 831 1050 1290 1590
3.2 70 152 269 402 561 761 959 1190 1470
3.4 61 133 239 364 511 697 882 1100 1360
3.6 51 113 206 329 465 640 813 1020 1260
3.8 42 96 177 294 422 586 749 939 1170
4.0 36 82 155 261 380 535 690 870 1090
4.2 31 72 136 234 343 488 635 806 1010
4.4 27 63 121 210 311 446 584 746 938
4.6 24 56 108 190 283 408 538 692 873
4.8 21 50 97 172 258 374 496 641 812
5.0 19 45 88 156 235 343 457 594 755
5.2 17 40 79 142 214 315 421 549 701
5.4 15 36 71 128 195 287 386 506 648
5.6 13 32 63 115 176 260 351 463 594
5.8 11 28 56 102 156 232 315 416 537
6.0 8 21 43 79 123 184 252 336 437
Vd=90km/hR(m) Vd=100km/hR(m)Vd=60km/hR(m)e(%) Vd=20km/hR(m) Vd=30km/hR(m) Vd=40km/hR(m) Vd=50km/hR(m) Vd=70km/hR(m) Vd=80km/hR(m)
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TABLE 4.8B: MINIMUM RADII FOR DESIGN SUPERELEVATION RATES, DESIGN
SPEEDS, AND emax = 8%
4.2.5 Transition Design Control
The superelevation transition section consists of the superelevation runoff and tangent runout sections. The superelevation runoff section consist of the length of roadway needed to accomplish a change in outside lane cross slope from zero to full superelevation or vice versa. The tangent runout section consists of the length of roadway needed to accomplish a change in outside lane cross slope from normal cross slope rate to zero or vice versa. For reasons of safety and comfort, the pavement rotation in the superelevation transition section should be effected over a length that is sufficient to make such rotation imperceptible to drivers. To be pleasing in appearance, the pavement edges should not appear distorted to the driver.
4.2.5.1 Spiral Curve Transition
Vehicles, i.e. motorcycles, follow a transition path as it enters or leave a circular horizontal curve. To design a road with built-in safety, the alignment should be such that a driver travelling at the design speed will not only find it possible to confine his vehicle to the occupied lane but will also be encouraged to do so. Spiral transition curves are used for this purpose. Generally, the Eulers spiral, also known as the clothoid is used. The degree of curve varies from zero at the tangent end of the spiral to the degree of the circular arc at the circular curve end.
1.5 184 443 784 1090 1490 1970 2440 2970 3630
2.0 133 322 571 791 1090 1450 1790 2190 2680
2.2 119 288 512 711 976 1300 1620 1980 2420
2.4 107 261 463 644 885 1190 1470 1800 2200
2.6 97 237 421 587 808 1080 1350 1650 2020
2.8 88 216 385 539 742 992 1240 1520 1860
3.0 81 199 354 496 684 916 1150 1410 1730
3.2 74 183 326 458 633 849 1060 1310 1610
3.4 68 169 302 425 588 790 988 1220 1500
3.6 62 156 279 395 548 738 924 1140 1410
3.8 57 144 259 368 512 690 866 1070 1320
4.0 52 134 241 344 479 648 813 1010 1240
4.2 48 124 224 321 449 608 766 948 1180
4.4 43 115 208 301 421 573 722 895 1110
4.6 38 106 192 281 395 540 682 847 1050
4.8 33 96 178 263 371 509 645 803 996
5.0 1 87 163 246 349 480 611 762 947
5.2 27 78 148 229 328 454 579 724 901
5.4 24 71 136 213 307 429 549 689 859
5.6 22 65 125 198 288 405 521 656 819
5.8 20 59 115 185 270 382 494 625 781
6.0 19 55 106 172 253 360 469 595 746
6.2 17 50 98 161 238 238 445 567 713
6.4 16 46 91 151 224 224 422 540 681
6.6 15 43 85 141 210 210 400 514 651
6.8 14 40 79 132 198 198 379 489 620
7.0 13 37 73 123 185 185 358 464 591
7.2 12 34 68 115 174 174 338 440 561
7.4 11 31 62 107 162 162 318 415 531
7.6 10 29 57 99 150 150 296 389 499
7.8 9 26 52 90 137 137 273 359 462
8.0 7 20 41 73 113 168 229 304 394
Vd=90km/hR(m) Vd=100km/hR(m)e(%) Vd=20km/hR(m) Vd=30km/jR(m) Vd=40km/hR(m) Vd=50km/hR(m) Vd=60km/hR(m) Vd=70km/hR(m) Vd=80km/hR(m)
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4.2.5.2 Length of Spiral (L)
The length of spiral or the superelevation runoff, L is determined by either vehicle dynamics or appearance criteria. Where spiral transition curves are used, the superelevation transition will normally coincide with the spiral. The following formula is used by some for calculating the minimum length of a spiral:
L =0.0214𝑉𝐷𝑆
3
𝑅𝐶
Where,
L = Minimum length of spiral (m) VDS = Design Speed (kph) R = Curve radius C = Rate of increase of centripetal acceleration (m/s3)
The factor C is an empirical value and a range of 1 to 3 has been used for highways (AASHTO 2011).
4.2.5.3 Minimum Length of Superelevation Run-off
For appearance and comfort, the length of superelevation runoff should be based on a maximum acceptable difference between the longitudinal grades of the axis of rotation and the edge of pavement. The axis of rotation is generally represented by the alignment centerline for undivided roadways. However, for the exclusive motorcycle lane, the axis of rotation is on the Edge 1 (see FIGURE 4.1) on the exclusive motorcycle lane, i.e. closest to the adjacent main road. More commonly, superelevation transition lengths for highways are based on appearance or comfort criteria. One such criterion is a rule that the difference in longitudinal slope (grade) between the Edge 1 and Edge 2 of travelled way of an exclusive motorcycle lane should not exceed the maximum relative gradient, Grmax, presented in TABLE 4.9, as stipulated in AASHTO (2011) and ATJ 8/86 (Pindaan 2015).
FIGURE 4.1 also illustrates the application of this rule based on an exclusive motorcycle lane. L is measured from the TS to the SC, as in the superelevation diagram see AASHTO (2006) or ATJ 8/86 (Pindaan 2015). At the TS the difference in elevation between the Edge 1 and Edge 2 is zero. At the SC it is the superelevation rate e times the distance D from the Edge
1 to the Edge 2. Since the criterion that the difference in grade Grmax, does not exceed the values in TABLE 4.9, with respect to the design speed, VDS, this implies that, L is given by equation:
L = Grmax x D x e
Where,
L = Minimum length of spiral (m) Grmax = Equivalent Maximum relative Slopes, refer to TABLE 4.9 D = distance from the Edge 1 to the Edge 2 (m)
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FIGURE 4.1: DIFFERENCE IN GRADE RESULTING FROM SUPERELEVATION TRANSITION (ONE LANE ROTATED INSIDE THE
EDGE PROFILE)
TABLE 4.9 : RELATIONSHIP OF DESIGN SPEED TO MAXIMUM RELATIVE PROFILE GRADIENT (AASHTO 2006)
Design Speed,
VDS
Maximum Relative Gradient (and Equivalent Maximum relative Slopes, 1: Grmax) for profiles between Edge 1 and Edge 2
20 0.80 (1 : 125) 30 0.75 (1 : 133) 40 0.70 (1 : 143) 50 0.65 (1 : 150) 60 0.60 (1 : 167) 70 0.55 (1 : 182) 80 0.50 (1 : 200) 90 0.47 (1 : 213) 100 0.44 (1 : 227)
TABLE 4.10A and TABLE 4.10B give the various design speeds and degree of curvature, the minimum lengths of superelevation runoff, the superelevation rates and the limiting curvatures for which superelevation is not required. As mentioned previously, the exclusive motorcycle lane is designed as a single carriageway with one lane traffic flow configuration, and thus, the number of lane rotated is one and its rotation axis is along Edge 1.
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TABLE 4.10A: DESIGN SUPERELEVATION TABLE FOR emax = 6%
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TABLE 4.10B: DESIGN SUPERELEVATION TABLE FOR emax = 8%
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4.2.5.4 Desirable Length of Spiral
Spiral curve transitions or spiral length is an important design control. Specifically, the most desirable operating conditions were noted when the spiral curve length was approximately equal to the length of the natural spiral path adopted by drivers. Differences between these two lengths will result in operational problems associated with large lateral velocities or shifts in lateral position at the end of the transition curve.
Based on these considerations, desirable lengths of spiral transition curve are as shown in TABLE 4.11, similar to ATJ 8/86 (Pindaan 2015) and (AASHTO 2011). These lengths correspond to 2.0s of travel time at the design speed of the roadway. This travel time has been found to be representative of the natural path for most drivers.
TABLE 4.11: DESIRABLE LENGTH OF SPIRAL CURVE TRANSITION
Design Speed, VDS Spiral Length (m)
50 28 60 33 70 39 80 44 90 50
4.2.6 Method of Attaining Superelevation
For the exclusive motorcycle lane, one specific method of profile design in attaining superelevation, is revolving the pavement about the inside edge profile. FIGURE 4.2 illustrates the method diagrammatically. The rate of cross slope is proportional to the distance from start of superelevation runoff.
FIGURE 4.2 illustrates the method where the pavement section is revolved about the inside edge profile. The inside edge profile is determined as the line parallel to the calculated centerline profile. One half of the required change in cross slope is made by raising the center line profile with respect to the inside pavement edge and the other half by raising the outside pavement edge with respect to the centerline profile.
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FIGURE 4.2: REVOLVING THE PAVEMENT ABOUT THE INSIDE EDGE PROFILE
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4.2.7 Sight Distance on Horizontal Curve
Another element of horizontal alignment is the sight distance across the inside of curves. Where there are sight obstructions (such as walls, cut slopes, buildings and guardrails), a design to provide adequate sight distance may require adjustment if the obstruction cannot be removed. Using the design speed and a selected sight distance as a control, the designer should check the actual condition and make necessary adjustment in the manner most fitting to provide adequate sight distance.
FIGURE 4.6A and FIGURE 4.6B in Arahan Teknik Jalan 8/86 (Pindaan 2015) can be used to easily check the Horizontal Sight Line Offset (HSO) needed for clear sight areas that satisfies SSD criteria for horizontal curve of various radii.
4.2.8 General Controls for Horizontal Alignment of the EML
In addition to the specific design elements for horizontal alignment, a number of general controls are recognized and should be used. These controls are not subject to empirical or formula derivation but are important for the attainment of efficient and smooth-flowing roads. These are:
a) The horizontal alignment should be consistent with the topography and lane width, thus preserving developed properties and community values. Winding alignment composed of short curves should be avoided. On the other hand very long straights should likewise, also be avoided. The maximum length of straight section of the lane should be limited, where possible, to 2 minutes travelling time.
b) The use of the minimum radius for the particular design speed should
be avoided wherever possible. Generally flat curves should be used, retaining the maximum curvature for the most critical conditions.
c) Consistent alignment should always be sought. Sharp curves should
not be introduced at the end of long tangents. Where sharp curves must be introduced, it should be approached, where possible, by successively sharper curves from the generally flat curvature.
d) For small deflection angles, curves should be sufficiently long to avoid
the appearance of a kink. Curves should be at least 150m long for a central angle of 5° and the length should be increased 30m for each 1°decrease in the centerline angle. The minimum length of horizontal curve on main roads, should be about 3 times the design speed, Lcmin= 3V (in meter). On high speed controlled access facilities the desirable minimum length of horizontal curve should be double the minimum length i.e. Lcdes= 6VDS.
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e) Any abrupt reversal in alignment should be avoided. The distance
between reverse curves should be the sum of the superelevation runoff lengths and the tangent run-out lengths.
f) The 'broken back' arrangement of curves should be avoided. Use of spiral transitions or a compound curve alignment is preferable for such conditions if it is unavoidable.
g) Other than tangent, flat curvature should also be avoided on high, long
embankment fills. In the absence of cut slopes, shrubs and trees above the roadway, it is difficult for drivers to perceive the extent of curvature and adjust their vehicle operation to suit the prevalent conditions.
h) Caution should be exercised in the use of compound circular curves.
While the use of compound curves affords flexibility in fitting the highway to the terrain and other ground controls, the simplicity with which such curves can be used often tempts the designer to use them without restraint. Preferably their use should be avoided where curves are sharp. Compound curves with large differences in curvature will introduce the same problems that arise at a tangent approach to a circular curve. Where topography or right-of-way restriction makes their use necessary, the radius of the flatter circular arc, should not be more than 50 percent greater than the radius of the sharper circular arc. A several-step compound curve on this basis is suitable as a form of transition to sharp curves. A spiral transition between flat curves and sharp curves is even more desirable. On one-way roads such as ramps, the difference in radii of compound curves is not so important if the second curve is flatter than the first. However, the use of compound curves on ramps, which results in a flat curve between two sharper curves, is not good practice.
i) The designer should ensure that the required sight distance (i.e.
decision sight distance) is provided when approaching interchanges and intersections.
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4.3 Vertical Alignment
4.3.1 General Considerations
Vertical curves to effect gradual changes between tangent grades may be any one of the crest or sag types depicted in FIGURE 4.3. Vertical curves should be simple in application and should result in a design that is safe and comfortable in operation, pleasing in appearance and adequate for drainage. The major control for safe operation on crest vertical curves is the provision of ample sight distance for the design speed: while research has shown that vertical curves with limited sight distance do not necessarily experience safety problems, it is recommended that all vertical curves should be designed to provide at least the stopping sight distance shown in TABLE 3 (AASHTO 2011). Furthermore, additional sight distance should be provided at decision points.
FIGURE 4.3: TYPES OF VERTICAL CURVES
Source : AASHTO 2011
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The rate of change of grade to successive points on the curve is a constant amount for equal increments of horizontal distance, and equals the algebraic difference between the intersecting tangents grades divided by the length of curve or A/L in percent per meter. The reciprocal L/A is the horizontal distance in metre required to effect a 1 percent change in gradient and is a measure of curvature. This quantity (L/A), termed k, is used in determining the horizontal distance from the beginning of the vertical curve to the apex or low point of the curve. The k value is also useful in determining the minimum lengths of vertical curves for the various design speeds.
The lengths of vertical curves used should be as long as possible and above the minimum values for the design speeds where economically feasible.
4.3.2 Crest Vertical Curves
Minimum lengths of crest vertical curves are determined by the sight distance requirements. The stopping sight distance is the major control for the safe operation at the design speed chosen. Passing sight distances are not used as it provides for an uneconomical design. An exception may be at decision areas such as sight distance to ramp exit gores where longer lengths are necessary.
The basic formula for length of a parabolic vertical curve in terms of algebraic difference in grade and sight distance (using an eye height of average riders of 1.49 m and object height of 0.20 m) are as follows:
Where S is less than L:
L =𝐴𝑆2
556
Where, S is greater than L:
L = 2𝑆 − 556
𝐴
Where, L = Length of vertical curve (m) S = Sight distance (m) A = Algebraic difference in grades (%)
TABLE 4.12 indicates the minimum K values that are to be used for crest vertical curves for the exclusive motorcycle lane, while TABLE 4.13A shows the length of the crest vertical curve, Lcrest corresponds to the algebraic difference in grade, A, and design speed, VDS.
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4.3.3 Sag Vertical Curves
At least four different criteria for establishing lengths of sag vertical curves are recognized. These are; (1) headlight sight distance, (2) rider comfort, (3) drainage control and (4) a rule of thumb for general use and this criterion is used to establish the design values for a range of lengths of sag vertical curves (AASHTO 2011). It is again convenient to express the design control in terms of the K value.
For overall safety on road sections, a sag vertical curve should be long enough that the light beam distance is nearly the same as the stopping sight distance (AASHTO 2011). Accordingly, it is appropriate to use stopping sight distance for different design speeds as the value of S. The resulting lengths of sag vertical curves for the recommended stopping sight distance for each design speed are shown in TABLE 4.12 which also corresponds to the minimum K value for sag vertical curves for motorcycle lane.
Where S is less than L:
L =𝐴𝑉𝐷𝑆
2
395
Where, L = Length of vertical curve (m) A = Algebraic difference in grades (%) VDS = Design speed (kph)
TABLE 4.12: THE MINIMUM K VALUE FOR CREST AND SAG VERTICAL CURVES, Lsag FOR MOTORCYCLE LANE BASED ON THE
CORRESPONDING DESIGN SPEED, VDS.
VDS (kph) Min. SSDMC (m) Minimum K value for crest vertical curves
Minimum K value for sag vertical curves
90 150 37 33
80 120 25 26
70 100 16 20
60 80 10 15
50 60 6 10
TABLE 4.12 indicates the minimum K values that are to be used for sag vertical curves for the exclusive motorcycle lane, while TABLE 4.13B shows the length of the crest/sag vertical curve, Lsag corresponds to the algebraic difference in grade, A, and design speed, VDS.
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TABLE 4.13A: THE LENGTH OF THE CREST VERTICAL CURVE, Lcrest CORRESPONDS TO THE ALGEBRAIC DIFFERENCE IN GRADE, A, AND DESIGN SPEED, VDS
Crest vertical
curve, Lcrest
Design Speed, VDS (kph)
50 60 70 80 90
Algebraic
difference in
grade, A (%)
V = 50kph V = 60kph V = 70kph V = 80kph V = 90kph
0 0 0 0 0 0 1 6 10 16 25 37 2 12 20 33 50 74 3 17 30 49 76 111 4 23 40 66 101 148 5 29 51 82 126 185 6 35 61 99 151 223 7 41 71 115 177 260 8 46 81 131 202 297 9 52 91 148 227 334
10 58 101 164 252 371 11 64 111 181 278 408 12 69 121 197 303 445 13 75 132 214 328 482 14 81 142 230 353 519 15 87 152 246 378 556
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4.3.4 General Controls for Vertical Alignment
In addition to the specific controls, there are several general controls that should be considered, as belows;
a) A smooth gradeline with gradual changes should be strived for in preference to a line with numerous breaks and short lengths of grade. While the maximum grade and the critical length are controls, the manner in which they are applied and fitted to the terrain on a continuous line determines the suitability and appearance of the finished product.
b) The 'roller coaster' or the 'hidden-dip' type of profile should be avoided. They are avoided by use of horizontal curves or by more gradual grades.
c) A broken back gradeline should be avoided, particularly in sags where
the full view of both vertical curves is not pleasing. This effect is very noticeable on divided roadways with open median sections.
d) On long grades, it is preferable to place the steepest grades at the
bottom and lessen the grades near the top of the ascent or to break the sustained grade by short intervals of higher grade instead of a uniformed sustained grade that might be only slightly below the allowable minimum.
e) Where intersections at grade occur on sections with moderate to steep
grades, it is desirable to reduce the gradient through the intersection.
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TABLE 4.13B: THE LENGTH OF THE SAG VERTICAL CURVE, Lsag CORRESPONDS TO THE ALGEBRAIC DIFFERENCE IN GRADE, A, AND DESIGN SPEED, VDS
Sag vertical
curve, Lsag
Design Speed, VDS (kph)
50 60 70 80 90
Algebraic
difference in
grade, A (%)
V = 50kph V = 60kph V = 70kph V = 80kph V = 90kph
0 0 0 0 0 0 1 10 15 20 26 33 2 20 29 40 52 66 3 30 44 60 78 99 4 40 58 80 104 132 5 50 73 100 130 165 6 60 88 120 157 198 7 70 102 140 183 231 8 80 117 160 209 264 9 90 132 180 235 296 10 100 146 200 261 329 11 110 161 220 287 362 12 120 175 240 313 395 13 131 190 260 339 428 14 141 205 280 365 461 15 151 219 300 391 494
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4.4 Combination of Horizontal and Vertical Alignment
Horizontal and vertical alignment of the exclusive motorcycle lane should not be designed independently (AASHTO 2011). They complement each other. Excellence in their design and in the design of their combination increases utility and safety, encourages uniform speed, and improves appearance, almost always without additional cost.
Proper combination of horizontal alignment and profile is obtained by engineering study and consideration of the following general controls.
a) Curvature and grades should be in proper balance. Tangent alignment or flat curvature at the expense of steep or long grades, and excessive curvature with flat grades, are both poor design. A logical design is a compromise between the two, which offers the most in safety, capacity, ease and uniformity of operation, and pleasing appearance within the practical limits of terrain and area traversed.
b) Vertical curvature superimposed upon horizontal curvature, or vice versa, generally results in a more pleasing facility but it should be analysed for effect upon traffic. Successive changes in profile not in combination with horizontal curvature may result in a series of humps visible to the driver for some distance, which is a hazardous condition.
c) Sharp horizontal curvature should not be introduced at or near the top of a
pronounced crest vertical curve. This condition is hazardous in that the driver cannot perceive the horizontal change in alignment, especially at night when the headlight beams go straight ahead into space. The hazard of this arrangement is avoided if the horizontal curve is made longer than the vertical curve. Also, suitable design can be by using design values above the minimum for the design speed.
d) Somewhat allied to the above, sharp horizontal curvature should not be introduced
at or near the low point of a pronounced sag vertical curve. Because the road ahead is foreshortened any but flat horizontal curvature assumes an undesirable distorted appearance. Further, vehicular speeds, particularly of trucks, are often high at the bottom of grades and erratic operation may result, especially at night.
e) Horizontal curvature and profile should be made as flat as feasible at entry/exit
(ingress/egress) into the EML where sight distance along both roads is important and vehicles may have to slow down or stop.
f) Examples of poor and good practices are illustrated in ATJ 8/86 (Pindaan 2015).
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5.0 CROSS SECTION ELEMENTS
5.1 Pavement
5.1.1 Surface Type
Pavement surfaces should be smooth, and the pavement should be uniform in width. The smoothness of the riding surface affects the comfort, safety and speed of motorcyclist. The important pavement characteristics that are related to geometric design of motorcycle lanes are the ability of a surface to retain its shape and dimension, to drain, and to retain adequate skid resistance and the effect on driver’s behaviour.
Proper selection of materials and an understanding of how they perform simultaneously within the composite pavement structure must be based on careful consideration of expected traffic loads, the environment, and proven evaluation and construction practices. Other considerations, including availability of materials and economics, will often influence which materials are ultimately selected.
While it would be cost prohibitive to always demand the highest quality materials for every job, materials must be of sufficient uniformity and quality to provide reasonable performance under expected traffic loading and environmental conditions.
Bituminous (asphaltic) and concrete are the most common surface materials generally used for pavement structure.
Before the appropriate type of pavement is selected, the designer needs to appreciate the advantages and disadvantages of each type of pavement. In particular, the maintenance cost over the design life of the pavement must be taken into consideration.
For the EML, it is advisable to use bituminous surface materials to reduce the severity of injury during fall when accidents happen.
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5.1.2 Design Standard
There are two types of standard design that have been selected and are to be used; flexible pavement and concrete pavement.
5.1.2.1 Flexible Pavement
A flexible pavement structure is typically composed of several layers of material with better quality materials on top where the intensity of stress from traffic loads is high and lower quality materials at the bottom where the stress intensity is low. Flexible pavements can be analysed as a multilayer system under loading. A typical flexible pavement structure consists of the surface course and underlying base and subbase courses. Each of these layers contributes to structural support and drainage.
For pavement design purposes, mixed traffic (axle loads and axle groups) is converted into the number of ESAL repetitions by using load factors. The structural design of a pavement is then based on the total number of ESAL passes over the design period. Load factor can be determined from theoretically calculated or experimentally measured lorries and axle loads.
Referring to TABLE 5.1 axle configuration and load equivalence factors (LEF) based on traffic categories used by HPU, ATJ 5/85 (Pindaan 2013): Manual for the Structural Design of Flexible Pavement, the LEF for Motorcycles is zero (0). It indicates that motorcycle gives just minimal damaging effects to the pavement structure.
Considering minimal damaging effect of motorcycles to the pavement structure, it is recommended that pavement design for exclusive motorcycle lanes is to be as shown in FIGURE 5.1.
FIGURE 5.1: FLEXIBLE PAVEMENT STRUCTURE Source: ATJ 5/85 (Pindaan 2013)
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5.1.2.2 Rigid Pavement
Rigid pavements are normally constructed of Portland cement concrete and may or may not have a base course between the subgrade and the concrete surface. Rigid pavements have some flexural strength that permits them to sustain a beamlike action across minor irregularities in the underlying materials. Thus, the minor irregularities may not be reflected in the concrete pavement. Properly designed, constructed and maintained, rigid pavements have long service lives and usually are less expensive to maintain.
There are several types of rigid pavements. However, for the EML, plain concrete pavement is chosen due to its low loading criteria. In general, it is recommended to apply plain concrete pavement in areas where the natural subgrade condition is favourable and uniformity of support can be achieved. Joints are placed at relatively shorter distances (3 to 6 m) within concrete slab to reduce amount of cracking.
FIGURE 5.2 below shows the recommended pavement structures as one of alternatives for motorcycle lanes.
FIGURE 5.2: RIGID PAVEMENT STRUCTURE Source: ATJ 5/85 (Pindaan 2013)
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TABLE 5.1: AXLE CONFIGURATION AND LOAD EQUIVALENCE FACTORS (LEF)
Vehicle Load Equivalent
Factore (LEF) HPU Class Designation Class
Cars and Taxis C 0
Small Lorries and Vans CV1 0.1
Large Lorries CV2 4.0
Articulated Lorries CV3 4.4
Buses CV4 1.8
Motorcycles MC 0
Commercial Traffic (Mixed) CV% 3.7 Source: ATJ 5/85 (Pindaan 2013)
5.1.2.3 Normal Cross Slope
Water ponding on paths has a significant impact on the riding comfort as well as safety to the motorcyclists where spraying leads to grit on motorcycles and riders. Cross slopes are an important element in the cross section design and a reasonably steep lateral slope is desirable to minimise water ponding. The normal cross slope of 2.5% should be adequate to effectively dispose of surface water.
5.2 Lane Width & Marginal Strips for Motorcycle Lane
Lane width and the condition of the pavement surface are the most important features of a road pertaining to the safety and comfort of driving. The capacity of an EML is affected by the lane width. The effective width of a travelled way is further reduced when adjacent obstructions such as retaining walls, bridge piers and parked cars restrict the lateral clearance. Marginal strip is a narrow pavement strip attached to both edges of a carriageway. It is paved to the same standard as the pavement structures. The marginal strips are provided on both sides of the carriageway in both directions. The marginal strip is included as part of the shoulder width and is demarcated from the through lane by lane edge markings on the marginal strip. TABLE 5.2 indicates the lane and marginal strip widths that are to be used.
It is important to specify optimum control width for EML to ensure that the design of EML is safe for all motorcycle riders. The resulting analysis is used to suggest a safe control width of pavement for a straight section of an EML. Result indicates that the safe control width of EML.
TABLE 5.2: LANE & MARGINAL STRIP WIDTHS
Design Standard Lane Width (m) Marginal Strip Width (m)
EML 3.00 0.25
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5.3 Shoulders
5.3.1 General Characteristics
A shoulder is the portion of the roadway continuous with the travelled way for accommodation of stopped vehicle, for emergency use and for lateral support of the pavement. TABLE 5.3 indicates the shoulder widths that are to be used. A typical cross section showing the road shoulder and verge as shown in FIGURE 5.4 (without shelter area) and FIGURE 5.5 (with shelter area).
TABLE 5.3: SHOULDER WIDTH
Design Standard Shoulder Width (m)
EML 1.00
Their main functions are:-
a) Space is provided for emergency stopping free of the traffic lane.
b) Space is provided for the occasional motorist who desires to stop for various
reasons.
c) Space is provided to escape potential accidents or reduce their severity.
d) The sense of openness created by shoulders of adequate width contributes to
driving ease and comfort.
e) Sight distance is improved in cut sections, thereby improving safety.
f) Road capacity is improved and uniform speed is encouraged.
g) Lateral clearance is provided for signs and guardrails.
h) Structural support is to the pavement is enhanced.
The term “shoulder” is variably used with a modifying adjective to describe certain
functional or physical characteristics. The following applies to the terms used here:-
i. The “graded” width of shoulder is that measured from the edge of the travelled way to the intersection of the shoulder slope and the foreslope planes, as shown in FIGURE 5.3 (Figure A).
ii. The “usable” width of shoulder is the actual width that can be used when a rider makes an emergency or parking stop. Where the sideslope is 1V:4H or flatter, the “usable” width is the same as the “graded” width since the usual rounding of
1.2m to 1.8m width at the shoulder break will not lessen its useful width appreciably. FIGURE 5.3 (Figure B and C) illustrate this clearly.
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FIGURE 5.3: GRADED AND USABLE SHOULDERS Source: ATJ 8/86 (Pindaan 2015)
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FIGURE 5.4: TYPICAL CROSS SECTION SHOWING ROAD SHOULDER AND VERGE
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FIGURE 5.5: TYPICAL CROSS SECTION SHOWING ROAD SHOULDER AND VERGE
WITH SHELTER AREA
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5.4 Traffic Barriers
5.4.1 General
A traffic barrier is an obstacle and a hazard in itself. The decision to install it should only be taken if other means of removing the obstacle it protects are impossible or prohibitively expensive, and that the barrier itself is not a greater danger than the obstacle it is intended to protect. If a traffic barrier does not fulfill its purpose of installation, then it should be changed to a different type of traffic barrier (i.e, traffic barrier with Additional Rub Rail or Special Impact Attenuators).
5.4.2 Traffic Barriers for Motorcycle Lane
Generally, Semi-Rigid Barriers minimum TL2 and with appropriate end treatment are recommended to be used and installed for motorcycle lane with some improvement to the traffic barrier performance for motorcyclists. Two methods are recommended, i.e. the first method is by covering the existing guardrail posts and opening under the guardrails beam with additional rub rail on the lower section of the guardrail system and the second method is by covering exposed posts with special impact attenuators. Attenuator absorbs energy and redirects the impacting motorcyclist by preventing the motorcyclist from impacting guardrail posts.
5.4.2.1 Method 1: Additional Rub Rail
The addition of rub rail to the lower section W-beam barrier systems is recommended to be used. FIGURE 5.6 illustrates the example of rub rail fitted to an existing W-beam. The photograph of additional rub rail is shown in FIGURE 5.7.
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FIGURE 5.6: SCHEMATIC DRAWING OF RUB RAIL FITTED TO AN EXISTING W-BEAM
Source: REAM GL 11/2011
FIGURE 5.7: PHOTOGRAPH OF RUB RAIL FITTED TO AN EXISTING W-BEAM Source: Safe Direction
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5.4.2.2 Method 2: Special Impact Attenuators
This method focuses on the ways to reduce consequences of a crash against a metal barrier. Impact attenuators, or dampers, that are fitted to existing guardrail posts, also serve to increase the impact surface and, due to their deformation properties, increases energy absorption on impact.
a) Plastirail
The device consists of a soft plastic fence covering barrier posts that can be fitted to existing barrier systems. It aims to combine both energy absorption properties and impact spreading properties. The photograph of plastirail fitted to existing barrier is shown in FIGURE 5.8.
FIGURE 5.8: PHOTOGRAPH OF THE "PLASTIRAIL" FITTED TO EXISTING BARRIER SYSTEM
Source: REAM GL 11/2011
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b) Mototub
The “Mototub” is similar to the Plastirail except that it is made from 70% recycled material. It is currently used in a number of European countries. The photograph of “Mototub” fitted to existing barrier is
shown in FIGURE 5.9.
FIGURE 5.9: PHOTOGRAPH OF "MOTOTUB" FITTED TO EXISTING BARRIER SYSTEM
Source: Sodirel
c) The Basic Motorcyclist Protection System (MPS)
The Basic MPS is a unique concept which controls and absorbs bodily impact against safety barriers, thereby affording motorcyclist greater protection. This innovative high-tensile mesh guardrail protection system reduces motorcyclist injuries and fatalities. The Motorcyclist Protection System (MPS) fitted to existing barrier is shown in FIGURE 5.10.
FIGURE 5.10: MOTORCYCLIST PROTECTION SYSTEM (MPS) FITTED TO THE EXISTING BARRIER SYSTEM
Source: Cegasa Internacional
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5.5 Underpass
5.5.1 Required Clearance
1. The clear vertical height of all structures above the roadway shall be a minimum of 3.5 meters over the entire width of traffic lanes and is to allow for future pavement resurfacing. Whenever resurfacing will reduce the clearance to less than 3.5 meters, milling will be required to maintain the minimum clearance.
2. For clearance requirement over railways and waterways, reference should be made to the relevant authorities.
3. FIGURE 5.11 indicates the clearance required for underpasses of various cross-sections.
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FIGURE 5.11: CLEARANCES AT UNDERPASS Source: Based on ATJ 8/86 (Pindaan 2015) with adjustment
3.5m 3.5m
3.5m
3.5m
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6.0 TREATMENTS FOR SPECIAL CONDITIONS
6.1 Treatment of EML Approaching Egress and Ingress
An exclusive motorcycle lane must provide egresses and ingresses for motorcyclists to exit or enter the EML at-grade intersection. Egress is a path of exiting from the motorcycle lane and ingress is a path to enter into the motorcycle lane. It allows access into and out from the exclusive lane and thus provide mobility from one destination to another destination. In Malaysia, the accesses that connect EML with main carriageway are often located near to or at grade-separated interchanges where speeds are expected to be low compared to that of the mainline segment. Egress and ingress are also one of the most hazardous locations on EML where motorcyclists are required to make critical decision whether to join or leave the main traffic stream. The most important factor a motorcyclist will need to consider in making any one of these manoeuvres (join or leave) is the availability of a gap between two vehicles that, in the motorcyclist’s judgement, is adequate for them to complete the manoeuvre. Gap acceptance decisions have serious consequences, whereby if poor decisions are made it will increase the likelihood of accidents happening.
The concept and function of egress and ingress can be interpreted to be similar to the ramp terminal of a main carriageway. Ramp terminal is generally designed with auxiliary lane (acceleration and deceleration lane). The main purpose of the auxiliary lane is to allow exiting or entering vehicles to change speeds in the lane rather than doing it in a through traffic lane. With this, vehicle-to-vehicle speed differentials in the through lane can be reduced and degree of interference with through traffic can be minimised. The provision of auxiliary lane is proven to reduce vehicular conflicts and accidents at ramp terminal area and this basic principle is adopted for the egress and ingress of EML to increase motorcycle safety but with some modification to suit the needs of motorcyclist.
The provision of an egress or termination of the lane shall be at least 100 m in advance before any intersection to allow motorcyclists to merge safely with the traffic on the main carriageway which are approaching the intersection. Meanwhile, the provision of an ingress or entering lane shall be at least 100 m after any intersection, to allow motorcyclists to merge safely with the EML (See FIGURE 6.1 and FIGURE 6.2 for layout). The photograph of an egress for motorcyclist to exit the motorcycle lane is shown in FIGURE 6.3.
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FIGURE 6.1: TYPICAL LAYOUT PLAN OF AN EGRESS
FIGURE 6.2: TYPICAL LAYOUT PLAN OF AN INGRESS
Note: V1 – 85th percentile speed of motorcyclist V2 – 85th percentile speed of main traffic
FIGURE 6.3: AN EGRESS FOR MOTORCYCLIST TO EXIT THE MOTORCYCLE LANE
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TABLE 6.1: DIMENSIONS FOR EGRESS AND INGRESS
Diverging Merging
Egress 𝐷𝑒 = 𝑣1 × 𝑤𝑒
3.24 𝑀𝑒 =
𝑣2 × 𝑤𝑒
2.16
Ingress 𝐷𝑖 = 𝑣2 × 𝑤𝑖
2.16 𝑀𝑖 =
𝑣1 × 𝑤𝑖
3.24
In the case of a grade separated intersection, exclusive motorcycle lane must provide both egress and underpass (or tunnel) for motorcyclists to allow them to have access to their choice of destination. An egress allows motorcyclists to exit and enter an at-grade intersection while the underpass will allow motorcyclists to continue travelling along the EML to destinations beyond the grade separated intersection. The alignment of an egress of an EML must be provided with proper geometric elements and adequate taper length that can be safely maneuvered by motorcyclists especially during merging with the mainline traffic. Lane width of the egress needs to be reduced to form a single stream of motorcycle traffic as they merge with the main traffic. Geometric alignment through underpass may be constrained by the provision and orientation of the underpass. This may also limit the safe and comfortable riding speed of motorcyclists travelling through it. Roundabouts/traffic circles are rarely used in the motorcycle lane network. However, it can be provided if deemed necessary. An intersection may be replaced by a roundabout/traffic circle if there are at least 2 entry arms and 2 exit arms which is equivalent to two motorcycle lanes intersecting each other. A mini roundabout/traffic circle with a size between 4 m - 20 m in diameter would be sufficient for the purpose, depending on the expected speed of circulating motorcyclists. Whatever type of intersection used, adequate signs and markings must be installed to inform and guide these motorcyclists.
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6.2 Treatment of EML Approaching Pedestrian Crossing
In order to ensure safe passage for pedestrian crossing the EML, pedestrian crossing facility shall be provided at places deemed suitable. Since the EML is separated from the main carriageway, there will be instances whereby crossings are necessary such as pedestrian going to the bus stop adjacent to the main road. Provision for pedestrian crossing facility and its type can be referred to JKR Malaysia Manual Fasiliti Keselamatan Jalan (2014). However it is advisable that the pedestrian crossing is built at-grade on EML. Pedestrian crossings should be placed preferably on a straight alignment, with adequate vision for both motorcyclist and pedestrian. Adequate signs and markings must also be installed to inform and warn motorcyclist. FIGURE 6.4 shows the schematic diagram of pedestrian crossing on EML.
FIGURE 6.4: SCHEMATIC DIAGRAM OF PEDESTRIAN CROSSING ON EML
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7.0 OTHER ELEMENTS AFFECTING GEOMETRIC DESIGN
7.1 Drainage
It is of importance that drainage system being put out in a proper manner and being considered carefully. The solution of drainage problems should not be regarded as a separate element of road or motorcycle lane design. Rather, considerations relative to drainage must accompany every step in location and design, so that the final design and resulting construction operation will provide for optimum drainage at affordable cost. This will also help in maintaining the road itself at a reasonable expense.
Drainage factors not only can cause pavement failure but it also can affect safety on the travel way of streets and highways. Even a thin layer of water on the travel way surface can cause motor vehicle especially motorcycle to hydroplane even at a low speed due to their light weight.
To avoid two major things aforesaid, it is notable that the water needs to be disposed immediately from the pavement surface by means of drains. The type of drains provided depends on whether the road is in embankment, cutting or on ground level.
FIGURE 7.1 shows the schematic drawing for drainage system on a flat terrain.
FIGURE 7.1: SCHEMATIC DRAWING FOR DRAINAGE SYSTEM
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The essence of placing a parallel drain between the main carriageway and motorcycle lane is to intercept the surface water from running across the path of motorcycle lane. This drain should also be provided with appropriately placed sumps and gutter to divert storm water run-off beneath the motorcycle lane. FIGURE 7.2 shows the schematic drawing for drainage system at the embankment and cut slope.
FIGURE 7.2: SCHEMATIC DRAWING FOR DRAINAGE SYSTEM AT EMBANKMENT
AND CUT SLOPE
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When designing the sag vertical alignment especially along the underpass, it is recommended that the lowest point of the sag (vertical IP) be located outside of the tunnel or centre of the hilly area to prevent water ponding or flooding. This can be achieved as shown in FIGURE 7.3.
FIGURE 7.3: EXAMPLE OF SAG VERTICAL ALIGNMENT ALONG UNDERPASS
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7.1.1 Gutter Drain
Gutter is a small channel provided at the edge of the roadways or shoulders for drainage purposes. They are not covered and can be V-Shaped or Egg-Shaped. When used with kerbs, gutters are located in front of the kerbs. Gutters can be precast or cast-in-situ and commonly used in urban roads or streets. It can be referred at Arahan Teknik (Jalan) 15/97 - Intermediate Guideline to Drainage Design of Roads. FIGURE 7.4 shows the types of roadside drain suggested for EML.
An example of this type of drain being used is at the existing EML (MEX Highway), as shown in FIGURE 7.5.
FIGURE 7.4: SUGGESTION TYPE OF TYPICAL ROADSIDE DRAIN FOR
EML
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FIGURE 7.5: EXAMPLE ON TYPE OF DRAIN AT EML -MEX HIGHWAY (KUALA LUMPUR – PUTRAJAYA)
Embankment Shoulder Drain 500mm Width
Embankment Shoulder Drain 500mm Width
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7.2 Lighting
Road lighting may improve the safety of a motorcycle lane, the ease and comfort of its operation thereon. The primary purpose of road lighting is to provide safe and comfortable vision during the night on motorcycle lanes. It also has a wider social role, i.e. in helping to reduce crime and also contribute in terms of its commercial and social use. The benefits of such lighting include reduction of accidents and facilitation of traffic flow.
Minimum average motorcycle lane luminance expressed in TABLE 7.1 is to be used as a general guideline in the design of road lighting system for motorcycle lanes. The guidelines are intended to establish the level of road lighting which covers the various sections of motorcycle lanes. The lighting layout should provide a uniformly bright carriageway to the desired levels. Nevertheless it should also be designed to prevent or reduce glare, and minimize its adverse impacts on all road users. FIGURE 7.6 shows the typical cross section for installation of lighting.
TABLE 7.1: MINIMUM AVERAGE MOTORCYCLE LANE LUMINANCE
Area Minimum Average Motorcycle Lane
Luminance, cd/m2
Merging & Diverging Gore Areas 2.0
Underpass (>30m) 1.5
Others 1.0 Source: REAM GL 11/2011
FIGURE 7.6: TYPICAL CROSS SECTION FOR INSTALLATION OF LIGHTING Source: REAM GL 11/2011 with adjustment
MOTORCYCLE LANE
SEPARATOR
CARRIAGEWAY
CARRIAGEWAY
CARRIAGEWAY
CARRIAGEWAY
SEPARATOR
MOTORCYCLE LANE
Minimum average luminance at EML
= 1.0 cd/m2
Minimum average luminance at EML
= 1.0 cd/m2
MEDIAN
EXCLUSIVE MOTORCYCLE LANE (EML)
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At tunnel or underpass which is longer than 10m, it is recommended that the full length of the structure be lit at all times. The designer shall take into account in the design, the transition lighting requirements at the entrance and exit to these tunnel/underpass so that minimum vision adjustment is experienced by the motorcycle riders.
The clearance between the lighting column and the edge of motorcycle carriageway should be not less than the minimum distance recommended in TABLE 7.2 for the appropriate design speed. The lowest point of overhang of luminaires or bracket arms that overhang the carriageway or area within the respective horizontal clearances in the table should have vertical clearances of at least 5.7 m from the level of the motorcycle carriageway surface.
TABLE 7.2: HORIZONTAL CLEARANCES (m) REQUIRED
Design Speed, kph Horizontal Clearances, m
20-50 0.8
60-80 1.0
90-100 1.5 Source: MS 825 Part 1:2007
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7.3 Utilities
All exclusive motorcycle lanes, whether upgraded within the existing right of way or entirely on new right of way, generally involves the shifting of utility facilities. Although utilities generally have little effect on the geometric design of the motorcycle lane, full consideration should be given to measures necessary to preserve and protect the integrity and visual quality of the motorcycle lane, its maintenance efficiency and the safety of traffic.
Utilities relocation should form part of design and the designer should liaise closely with the relevant service authorities in determining the existing utilities and their proposed relocation.
7.4 Signages and Markings
Signages and markings are directly related to the design of the motorcycle lane and are features of traffic control and operation that the engineer must consider in the geometric layout of such a facility. The signages and markings should be designed concurrently with the geometrics as an integral part, and this will reduce significantly the possibility of future operational problems.
7.4.1 Road Markings
The markings should follow the standards that have been established. Reference should be made to the latest revision of the guidelines approved by JKR on the design, usage and application of markings. Edge line for the motorcycle lane shall be continuous white lines with 100mm width.
7.4.2 Traffic Signs
Just like road markings, traffic signs regulate, warn and advise users on the dangers ahead of them. There are many signs and their location is of fundamental importance for the road users to act on them. This is to give the road users ample time to act on seeing the signs.
The references should be made to the latest edition guidelines approved by JKR. For Guide signs showing distance, letter height H, shall be 150mm and for gantry type, H shall be 200mm. Guide signs should be located at a distance of 1 km and 500 m in advance of the turning roadway. Minimum clearance height for gantry shall be 3.5m.
Warning signs B, C, J, and K as in FIGURE 7.7 shall be installed at the main road and at the entrance and exit of motorcycle lane with the distance as required.
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FIGURE 7.7: TRAFFIC SIGNS FOR EXCLUSIVE MOTORCYCLE LANE Source: Standard Drawing for Road Works (Section 9: Motorcycle Lane)
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7.5 Erosion Control, Landscape Development and Environmental Impacts
Erosion prevention is one of the major factors to consider in the design, construction and maintenance of highways. It should be done early in the design stage and possible high risk locations identified. Some degree of erosion control measures can be incorporated into the geometric design, particularly in the cross-section elements.
Landscape development should be in keeping with the character of the road and its environment. The general areas of improvement include the following: -
a) Preservation of existing vegetation b) Transplanting of existing vegetation where feasible c) Planting of new vegetation d) Selective clearing and thinning e) Regeneration of natural plant species and material.
Landscaping of urban roads assume an additional importance in mitigating the many nuisances associated with urban traffic.
Reference should be made to the relevant JKR Manual / relevant Authorities on this subject, namely: -
(i) Latest edition of ATJ 16/03 – A Practical Guide for Environmental Protection & Enhancement Works
(ii) Cawangan Alam Sekitar & Kecekapan Tenaga (iii) ESCP, MSMA (JPS) (iv) Jabatan Alam Sekitar (v) Jabatan Lanskap Negara
The highway can and should be located and designed to complement its environment and serves to cater for future environmental improvement. The area surrounding a proposed highway is an interrelated system of natural, manmade and sociological variables. Changes in one variable within this system will undoubtedly affect the others. Some of these consequences may be negligible, but others may have a strong and lasting impact on the environment, including those involving the sustenance and quality of human life.
Because highway location and design decisions have an effect on adjacent areas and its surrounding development, it is thus important that environmental variables be given full consideration. Environmental impacts include those of social, economic and physical. In geometric design, only physical impacts are assessed, while the social and economic impacts would have to be taken care of during the planning stage.
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REFERENCES
1. AASHTO, 2006. Roadside design guide, American Association of State Highway and Transportation Officials, Washington
2. AASHTO, 2011. A policy on geometric design of highways and streets. Washington D.C.
3. Fambro, D.B., Fitzpatrick, K., Koppa, R.J., 1997. Determination of stopping sight distance, Report 400, Texas Transportation Institute, Washington D.C.
4. Hussain H., Radin Umar R.S., Ahmad Farhan M.S., Dadang M.M., 2005. Key Components of a Motorcycle-Traffic System: A Study along the Motorcycle Path in Malaysia, Journal of International Association of Traffic and Safety Sciences, Japan, Vol. 29, No.1, May 2005, pp. 50-56
5. Hussain H., Radin Umar R.S., Ahmad Farhan M.S., 2011. Establishing Speed-Flow-Density Relationships for Exclusive Motorcycle Lanes, Journal of Transportation Planning & Technology, Taylor & Francis,Vol. 34, No.3, April 2011, pp. 245-257
6. Hussain H. 2006. Development of Capacity and Level-Of-Service for Uninterrupted Exclusive Motorcycle Lanes in Malaysia, PhD Thesis, Faculty of Engineering, Universiti Putra Malaysia. (unpublished)
7. JKR, Arahan Teknik Jalan 8/86. A guide on geometric design of roads. Road Branch: Public Works Department Malaysia, Kuala Lumpur, Malaysia. (Revision 2015)
8. JKR, Arahan Teknik Jalan 5/85. Manual for the Structural Design of Flexible Pavement. Road Branch: Public Works Department Malaysia, Kuala Lumpur, Malaysia. (Revision 2013)
9. Lenkeit, J.F., Hagoski, B.K., Bakker, A.I., 2011. A study of motorcycle rider braking control behavior, DOT HS 811 448, National Highway Traffic Administration (NHTSA).
10. MS 825 Part 1: 2007. Code Of Practice For The Design Of Road Lighting - Part 1: Lighting Of Roads And Public Amenity Areas (First Revision)
11. REAM GL 2/2002. A Guide on Geometric Design of Roads. Road Engineering Association of Malaysia, Shah Alam, Selangor, Malaysia.
12. REAM GL 11/2011. Guidelines for Motorcycle Facilities. Road Engineering Association of Malaysia, Shah Alam, Selangor, Malaysia.
13. REAM GL 7/2004. Guidelines to the Design of Plain Concrete Pavement. Road Engineering Association of Malaysia, Shah Alam, Selangor, Malaysia.
14. Safedirection.com.au 15. www.highwaycare.co.uk
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