Road Design Manual 1.3


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Road Design Manual 1.3

  1. 1. Reference guide for urban road design Suhas Kulhalli ( Concept, Compilation and Editing Technical contributors: Adhiraj S Joglekar: Road layouts, standards Ganesh Gaikwad ( Signage Reviewers K.V Pathy: Bus-stops R.N Kulhalli: Language Other contributiors Pranav Jha, P.S. Anantharaman Supporting organisations incubation, comments etc Version Release Notes Release No: Date 1.0 Skeletal Draft. Basic structure of document. Section 1 to 4 complete. 5-Apr-09 Section 5, only two examples complete. Even here, figures and pictures need to be added. Section 6,7,8 only idea is given. Document not yet formatted. 1.1 Added some figures and minor edits 20-Apr-09 1.2 Added section on intersections, ongoing 01-Jun-09 1.3 Many sections added. Added an example template. Deleted the notes 01-Sep-09 section in appendix
  2. 2. Contents 1. Introduction................................................................................................................. 3 2. Objective ..................................................................................................................... 3 3. Approach..................................................................................................................... 6 4. Uses of streets ............................................................................................................. 8 4.1 People movement................................................................................................ 8 4.2 Static uses............................................................................................................ 8 4.3 Environmental functions..................................................................................... 8 4.4 Utility uses .......................................................................................................... 9 5. Requirements/specifications for each use................................................................. 10 5.1 People movement.............................................................................................. 10 5.2 Static uses.......................................................................................................... 31 5.3 Environmental functions................................................................................... 36 5.4 Utility uses ........................................................................................................ 37 6. Design example............................................................................................................. 38 7. Classification of Roads ................................................................................................. 38 8. Design templates for each road type............................................................................. 39 Glossary ............................................................................................................................ 42 References......................................................................................................................... 43 Interesting links................................................................................................................. 44 Some useful dimensional information .............................................................................. 45
  3. 3. 1) Introduction Streets are the arteries of urban communties. They are the ones which provide mobility for men and material. They are also used for water, sewerage, telecom, electricity distribution alike. They also to a large extent determine the character of the city. Well designed and well maintained streets can make a perceptible difference to the quality of life. In this document, we deal with streets in the urban and semi-urban context. Streets and roads are used interchangeably to mean the same thing. When building a road, there are different aspects which come into play. We can classify them as under • Geometric design Relating to the road layout, i.e. the plan view and section view from an engineering drawing viewpoint. Thus, the width of pavement(vehicular portion), footpaths, intersection design, position of streetlights, trees & street furniture, height of kerb etc all come under this • Construction and Maintaineance Relating to the actual materials, quality of construction. Implementation of a given geometric design would mostly fall in this classification. • Administrative These could be the actual tendering process, financials, systems for monitoring and maintenance etc. Our focus is going to be the geometric design aspect. The geometric design of streets can make a huge difference how efficiently it carries out its functions, and its safety. 2) Objective The general expectations from a street are listed below. In other words, these are the principles/objectives on which street design should be based. 1. Safety This is the primary concern. A road should be safe for all users, including and specially pedestrians, cyclists, the elderly and the handicapped. In the absence of good designs and enforcement, might is right rules, traffic can be chaotic and unsafe. 2. Ease of navigation We frequently have faced situations when a parked car is abutting a road, or pedestrians standing in the middle of the road causing the vehicle driver to swerve, or at U-turn with cars piled up obstructing the straight moving traffic. All this results in the driver always on the edge, and can never relax. This makes the whole driving experience a stressful one. Similar is the case with pedestrians. With no clear cut footpath or pedestrian crossings at intersections, it can be a very stressful experience just crossing a road, or even walking on the footpath This need not be the case. Ease of navigation can always be achieved, as against speed of navigation. Speed depends on the road available and traffic. However, navigation, irrespective of traffic density, both
  4. 4. of pedestrians or vehicles can be made easier and stress free by better designs of roads and intersections. 3. Quick and smooth movement Design should ensure quick and smooth movement of vehicles. This does not mean that vehicles should go with high speed, rather that they can maintain a decent average speed over their drive. 4. Aesthetics Pretty, Neat, Clean and Green. Should be beautiful and beautiful roads is what makes the city look pretty. Neat, with clearly marked lanes, straight footpath edges, no protrusions, are all required of the road. Cleanliness should be built in, that is, it should be easy to clean and maintain. Roads present a wonderful opportunity to add to the green cover of the city. Trees and other greenery along the roads can make it a very pleasant experience. 5. Optimal space utilization To achieve all the above, we must keep in mind that space is at a premium in the urban cities. All the above must be achieved within the given or reasonable width of road. To do this one must design innovative and efficiently. Thus the roads must be comprehensively designed to make efficient use of available space, taking into account all its uses. Examples of some functions are street furniture such as bus- stops, street lighting, utility lines such as electrical, water and drainage, cables etc. What are the requirements/ specifications of each aspect of the road, so as to meet the above objectives ? How does one approach the design to meet the above ? This are some of the things this document is about and we will address these in the coming sections
  5. 5. . If nothing else, this should really get us focused on better road design. A systematic approach as detailed in this document should result in better designed roads, safer for everybody and resulting in lives saved. No effort is too high if it results in saving of lives.
  6. 6. 3) Approach To get to a design which is comprehensive and looks at all aspects of the road, we go about it in the following way. First, we list all possible uses of a road. These include, but are not limited to vehicular (2,3 & 4 wheelers), cyclists, pedestrians, bus-stops and other street furniture such as streetlights, electric lines, utility lines, drainage and sewerage, parking, hawkers etc. Make a comprehensive checklist to make sure all possible utilizations are included. Next, for each of these uses, we list down all the requirements. To come up with these requirements, we need to place our selves in position of the user/utility provider and look at what would be required to meet the above mentioned objective. In addition, one needs to look at specifications and guidelines of the IRC (Indian Road congress) and equivalent international standards. These will then be collated and organized in a systematic manner. Once the requirements of each of the use cases has been obtained a detailed checklist needs to be formed, which would incorporate all the requirements for all the uses. As one goes through the process of road design, one should ensure at the end of it that the checklist is gone through and all have been met. It would be cumbersome to do this process for each road that comes up. Not only this, if we come up with a different design each time, the lack of consistency will confuse road users and lead to further accidents. Hence, it is imperative that this be standardized to some extent. The way this can be done is to build a reference design. These essentially have the plan view and section view of a typical road section. For any new road, this should be adhered too. Now obviously one reference design will not suffice for the variety of roads that are in use in a city. For example, a residential road will look quite different from an arterial road. Thus there is a need to make many such reference designs for a variety of roads. To do this, roads should be categorized depending on their primary use and width. A reference design should be then done for each of these road types. This becomes a template developed for these type of roads, and one would have a template for each road type. A similar approach and template designs are covered in IRC7. However, these reference designs are not comprehensive, and are primarily done only to give the desired road width requirements. Lastly, for this to have an impact city-wide, these templates should be mandatory part of the road specifications and tendering process. If the road developed is given to a private contractor, it should be ensured that the geometric design is specified and the given template is adhered too. Over time, this will ensure all roads have a basic uniformity, as well as are optimized to meet the local need and the broad objectives set out at the beginning of the document.
  7. 7. 4) Uses of streets There is more to a street than movement of vehicles. It also needs to be safe, usable and appealing for pedestrians, cyclists and handicapped. It is also used for parking, turns, used by hawkers, etc. For better understanding we will classify and list these down. 4.1 People movement 4.1.1 Thoroughfare for motorized vehicles 2 wheelers 3 & 4 wheelers, light commercial vehicles Greater than 4 wheelers, heavy commercial vehicles. 4.1.2 Thoroughfare for non-motorized vehicles Pedestrians Cyclists 4.1.3 Street intersections, turns and pedestrian crossings Design considerations Intersection types and additional requirements 4.2 Static uses 4.2.1 Parking 2 wheeler parking 4 wheeler parking 3 wheeler[rickshaw],Taxi and Para-transit parking Heavy vehicles parking 4.2.2 Hawkers 4.2.3 Bus-stops and transit facilities 4.2.4 Streetlights 4.2.5 Hoardings/advertisement banners 4.3 Environmental functions 4.3.1 Trees 4.3.2 Garbage bins 4.3.3 Rain water run off
  8. 8. 4.4 Utility uses 4.4.1 Electricity 4.4.2 Water 4.4.3 Sewerage 4.4.4 Telephone cables 4.4.5 Internet cables 4.4.6 Cable TV 4.4.7 Others
  9. 9. 5) Requirements/specifications for each use Requirements of each use case will be listed comprehensively, taking inputs from multiple sources. Were possible, the requirement will be specified numerically. The first source for the requirements would be IRC documents. In case requisite IRC guidelines are unavailable or insufficient, other national standards(primarily UK) are used. 5.1 People movement 5.1.1 Thoroughfare for motorized vehicles 2 wheelers 3 & 4 wheelers, light commercial vehicles Greater than 4 wheelers, heavy commercial vehicles. 5.1.2 Thoroughfare for non-motorized vehicles Pedestrians 1. Width of footpath [also called side-walk] IRC guidelines1 stipulate that the minimum width of a footpath should not be less than 1.5m. Width should depend on pedestrian traffic, varying between 1.5m at a minimum to a maximum of 4.0m. H Pole with the cross-bar on the left, Bus-stop on the top right and Electric Box and o tree in the bottom rightpicture on the right obstruct the footpath and make it w unusable
  10. 10. ever, in addition to providing footpath for pedestrians, it is equally important to see that this complete width is always available throughout the road and is unobstructed. Frequently, we observe that the footpath is not clear, either because of hawkers, parking, bus-stops etc. So part of providing a quality footpath is to provide different spatial arrangements for these. Whenever there is a constriction in the footpath, the person in order to skip it will walk on the road. Then, even if a clear stretch of footpath is available, there is a tendency to continue walking on the road. Also, a pole in the middle will halve the space available for the wheelchair, and may make it unusable for the handicapped. Figure on the left shows how the footpath is obstructed by a tree and pole, causing the pedestrian to avoid the footpath altogether. On the right, pole is on the edge and trees are in a separate line outside the footpath, giving unobstructed space for the pedestrian. Hence, the footpath should be unobstructed throughout. To enable this, street furniture such as electrical poles, lamp posts, trees etc should be placed one edge of the footpath and not arbitrarily somewhere on the footpath. Similarly pole transformers should be at such a height so as to not obstruct pedestrians. Where absolutely unavoidable, in presence of localized obstructions, the unobstructed width of a footpath should not be less than 1m to allow a wheelchair(815mm) to pass comfortably. Overhangs if any should be at a height greater than 3m from the footpath level.
  11. 11. Figure on the left shows how a tree obstructs the footpath, no clear parking space for car and pedestrian walks right in the middle of the lane. On the right, trees planted strategically, car nicely tucked in the middle, pedestrians get wide clear pretty footpath and vehicle lanes are unobstructed. Everybody’s happy! 2. Kerb Height The footpath would usually be at a slightly elevated height referred to the paved road. This gives protection to the pedestrians, prevents vehicles from coming over to the footpath and helps better segregation. Kerbs may be provided at the road edge to increase this segregation. The IRC2 recommends kerb heights between 325mm to 200mm on the road side with the footpath elevation of 125mm with respect to the paved road. A high kerb forces the car park away However, we find that, this height is more than the clearance of vehicle doors (~250mm, Ground clearance of Maruti 800, Hyundai Santro is 170mm). So in the case of parallel parking, it becomes inconvenient to open the passenger side door of the car. This results in the vehicle being parked at a distance from the kerb, thus using valuable road space. Hence, it is recommended that in case there is provision for parking adjacent to the footpath, the additional kerb barrier be done away with. That is, the footpath is maintained at an elevation of 125mm with respect to the paved road, and the kerb stones are flush with the footpath. Consideration must also be given to prevention of vehicle users (specially two wheelers) onto the footpath wherever such a possibility exists. 3. Access ramp or Dropped Kerbs
  12. 12. Footpaths need to be frequently broken for cross-roads, car parking ramps and other reasons. Usually it is observed that in such a case, the footpath is stopped abruptly. This makes it inconvenient for pedestrians and becomes impossible for the wheelchair bound to get on to the footpath. Hence a gradual gradient must be given, which should not exceed 1:9.6 Care should be taken to make it non-slip. Where relevant, provision should be made to prevent access to the footpath by vehicle users (especially two wheelers), without compromising pedestrian or wheelchair access. No standard design exists for this and such a design needs to be developed. With no dropped kerb, even with a wide beautiful footpath on the left, people will tend to skip and walk on the road. Figure on the right shows idea of dropped kerb, such that is is usable even by the wheelchair bound. 4 4. Identity maintained Whenever the footpath is broken for certain distance, because of cross-roads, intersections, car parking ramps and others, the identity of the footpath should be maintained. This means, as far as the pedestrians are concerned, the footpath would continue in a similar form on the paved road. Thus, that part of the road is of the similar texture of the footpath. This would make it easier for pedestrians as they clearly know what area to walk on, and for the vehicle drivers would to be extra cautious as they drive on that area.
  13. 13. Figure on the left shows how the footpath gives up its identity for an off lane. On the right one can see how the identity of the footpath is maintained, infact enhanced even more. 5. Crossfall The IRC guideline2 here stipulates that the crossfall should be within the range of 2.5% to 3%. If it is too flat, it is difficult to drain, whereas if it is too steep, it would get dangerous to walk on. 6, Surface quality They should have an even, firm, well-drained surface which is non-slip in both wet and dry weather. Joints should be closed and flush to prevent small wheels, walking sticks and canes from becoming trapped. Figure on the right shows the more desirable footpath surface – even, firm, non-slip, no gaps big enough to cause walking sticks etc being trapped. Covers and gratings in particular should be flush with the surface, nonslip, and have no openings greater than 13mm wide6. It is preferable to avoid the use of gratings or 'slot' type drainage within pedestrian areas and at pedestrian crossing points because they can trap small wheels and canes. However, if this is not possible, then gully covers and drainage slots should be positioned as far as possible from and at right angles to the main pedestrian flow lines. The surface color should contrast with that of the surroundings, and especially that of the road used for vehicular traffic. 7.Longitudinal gradients For pedestrians and especially for wheelchair bound, sudden or irregular gradient changes should be avoided, with gradients kept to 1:20 or less where possible. Wherever this is not possible, a maximum gradient should never exceed 1:12.6
  14. 14. Optional 8. Markings to aid blind people While this is highly desirable, good quality footpath which maintain 1 to 7 above should be first achieved. Then one needs to begin working on making these disabled friendly. No IRC guidelines on this aspect are available. However, there are a number of other national standards5,6 which have detailed guidelines for these. 9. Verge and barrier Verges or nature strips, in addition to beautifying the road, are useful to accommodate electric poles, lighting columns. In addition, they ensure proper vehicle placement and development of full carriageway capacity (IRC2). They also improve segregation between footpath and the paved road. Wherever space is available, verges with minimum of 1m width should be given. Wherever appropriate, pedestrian guard-rails can be given (IRC1). One must be aware that it would not be beneficial to provide parallel parking where guard rails are present as one would need to park at a distance to be able to open the vehicle door. Hence, angular parking must be provided wherever parking is provided next to a guard rail. Guard –rail helps the control and regulation of pedestrian traffic. However, if quality footpaths are not provided, pedestrians are likely to use the paved road and will be further dissuaded from using the footpath even in quality streches. Guard-rail designs are given in IRC3 Barriers can add to the safety element for pedestrians.. Cyclists 5.1.3 Street intersections, turns and pedestrian crossings
  15. 15. There are a number of different types of intersections which occur in practice. Examples are the cross streets, pedestrian crossings, traffic rotaries, staggered intersections etc. However, there are some common considerations which would apply to all intersections discussed. We will go through these considerations first (section a). We would then discuss the different types of intersections, and if there are any additional requirements for these, they will be discussed alongside. The design should be based on what the vehicle driver/pedestrians are most likely to do, rather than what we want them to do. Design considerations Design considerations can be categorized as from a vehicle perspective or a pedestrian cyclist perspective, though some are common. We will first look at the considerations from a vehicle, followed by pedestrian and then cyclist. Design considerations for vehicles 1. Turning radii The path of the turning vehicle needs careful observation, to ensure there is sufficient space for the vehicle to turn and that there is no conflict between the turning vehicle and the vehicles in other lanes. Similarly, the path of vehicles and those of pedestrians needs to be carefully thought through to ensure smooth flow of both and maximum safety. The figure shows the step by step path of a vehicle turning left at an angle of 90 deg. As can be seen, additional space is required as compared to lanes intersecting at 90 deg. For the sake of this discussion, we will look at the space required to the left for a left turning vehicle, so that it does not encroach onto any other lane than the space to the left of the leftmost lane. For urban intersections, assumptions are that the speed of the turning vehicles are slow and the calculations are based on the vehicle almost stopping before turning. In general, if there is a space available for an additional lane on the left, it should be sufficient for the turning vehicles.
  16. 16. Figure showing the extra area required for a turn. These numbers are derived from the standards but are for reference only, ie to give a feel. For actual design, you must refer to IRC8 Similar is the case for the U-turn. Usually the vehicle manufacturer will give the minimum turning radius, which will correspond to ½ of x in the figure. Appendix 1 gives some turning radii for vehicles. For eg: Volvo bus has a minimum turning radius of 11.5m which corresponds to x=23m in the fig. Thus these are minimal numbers with some margin. 2. Visiblity Assume you are approaching an intersection, ie a cross road at a particular speed. You see another vehicle also approaching the intersection on the cross-road. If the intersection is non-signalled, you need to have a view of the approaching vehicle sufficiently before, so that you can respond and slow-down/stop by the time you reach the intersection. This is a function of the speed of your vehicle as well as of the speed of the other vehicle, ie the vehicle on the cross-road. Given there is a human response time and a vehicle response time, there would be a safe stopping distance which would be a function of speed. The sight triangle visibility would be a direct function of this safe stopping distance. IRC8 gives two kinds of non-signalled intersections, i) “Uncontrolled intersections” where the intersecting roads are of more or less equal importance and there is no established priority. Here the safe stopping distance is a function of the design speed of each of the roads and the sight triangle is based on this. Please refer to figure and table alongside. ii)“Priority intersections” like minor road intersections where one road takes virtual precedence over the other. Traffic on minor road may be controlled by Stop or Give way signs/road markings. For these intersections, IRC8 recommends a minimum visibility of 15m along minor road and a sight distance equal to 8 seconds travel long major road. Please refer to figure and table alongside.
  17. 17. Figure showing the visibility requirements for an intersection. In the triangle formed by the intersecting roads and the line of sight, there should be no obstruction between 0.6m to 1.8m. These numbers are derived from the standards but are for reference only, ie to give a feel. For actual design, you must refer to IRC8 In addition to the above, IRC recommends that there be a subjective view of the overall visibility of the intersection layout. This can be done by a simple view of holding the junction drawing horizontally at eye level and observe the proposed layout from the direction of each approach, or by drawing in a 3D tool and observing from eye level at each approach. 3. Conflict avoidance A number of approaches to better traffic movement at junctions have been clubbed under this section. At an intersection, there are vehicles and people coming in from different directions and attempting to go to different directions. This gives potential conflict points, ie points were vehicles cross each others path as well as where vehicles cross the path of pedestrians. The techniques elaborated herewith would help minimize and better manage such conflict points. As such, these techniques deal with the space (physical aspect). Conflict avoidance, especially in intersections with heavy traffic, also needs time separation, which is by putting in signaling. This is dealt in section 6. a. Channelizing islands Figure shows channelizing islands(1,2) which avoid conflict, make the traffic flow orderly and safe.
  18. 18. Channelizing island helps segregate left turning traffic as well as doubles up as a pedestrian refuge Combination of channelizing islands and narrow lanes for traffic calming.9 Examples of channelizing islands also serving as pedestrian refuge’s. A number of pictures of channelizing islands have been shown. The above are to give a feel and are not the only shapes recommend. Section 4.11 of IRC8 gives the standards for channelizing islands. These are islands formed either by marking, kerb of a physical structure used to guide the flow of traffic as also assist pedestrians in road crossings. Things to keep in mind while designing a Channelizing island – - Area must be sufficient to be visible. IRC8 recommends at least 4.5 sq.m. In case of triangular islands, the recommended length of a side is 4.5m, 3.5m minimum.
  19. 19. - Offset from the swept path of the vehicle by 0.6m. The approach should be clearly marked where necessary. - Should be clearly visible. Should be bordered with painted raised Kerbs, reflectors for night visibility, and where necessary, a painted sign or ballard placed suitably on the island. - Suitable carriageway marking to guide actual vehicle Channelizing island for U-turn Note the use of painted areas to encourage allowed movements, while at the same time providing space for vehicle swept path. b. Auxillary lanes Auxiliary lanes exist only for short distances. They perform functions such as storage for turning vehicles, acceleration or declaration from the main carriageway. In the urban areas, except for expressways, acceleration or deceleration lanes are generally not provided, except for short distances. Here the function is more for merging and diverging and can be assisted by channelizing islands. The primary careabout here is to ensure good visibility between merging lanes, sufficient curve radius, and sufficient distance to accelerate/decelerate. Auxillary lanes, specifically acceleration/deceleration lanes used for short distance for merging and diverging Storage lanes or turning lanes are important in urban areas where volume of right turning traffic is more and if not catered too, blocks the through traffic. Additionally, because it segregates traffic, it reduces the number of conflict points and helps make the
  20. 20. traffic flow more orderly. It is recommended that all arterial roads and most collector streets have turning lanes for turns. Careabouts while designing a storage lane are8 - storage lane length must be based on 1.5 times the average number of vehicles that would store at peak hour, at a minimum - for purpose of calculation, take length of each car as 7.5m and truck/bus as 11m - length of area for taper (ie creation of the extra lane) should be in the range of 30 to 45m. This should be a smooth curve.8 Picture shows different examples of implementation of the concept of storage lanes for turning. 4. Traffic calming The slowing of aggressive drivers, ie fast vehicles for the safety of all road users may be understood as traffic calming. This may be required at intersections, turns, pedestrian crossings, residential neighborhood and so on. Unfortunately, in India, this has not gone beyond the use of speed breakers. Speed-breakers are not the only method of traffic calming. There are many others, and this section will give some examples. The idea is to
  21. 21. open up the road designer to the different possibilities, so that he uses the appropriate method or combination of methods while designing the road. The ad-hoc use of speed-breakers is one of the major reasons for traffic fatalities in the country. See attached picture for some newspaper snap-shots which are only indicative of the surface of the problem. Not only should speed-breakers judiciously be used, they should be part of a comprehensive road design. The other methods of traffic calming detailed below, as well as proper segregation of pedestrians/cyclists/vehicles, reduction of conflict points and other such commonly used road design techniques will help reduce the number of accidents. We have paid a very high price for not having focused on good quality road designs. a. Speed breakers As mentioned above, speed breakers (or road humps as they are also called) need to be very carefully and judiciously used. Though IRC10 has given a generic design, it
  22. 22. states that only one design of speed breaker may not be appropriate in all cases, and each one has to be looked into separately. However, it would be appropriate for the Municipal bodies to standardize on a few designs. When designing a speed breaker, following should be taken into consideration An IRC recommended speed breaker design. However, IRC does not limit it to only this. Source: Delhi Traffic Website - What is the speed it is designed for ? Ideally the ride should be comfortable upto design speed and increasingly uncomfortable at higher speed - What are the vehicles it is designed for ? Important that there should not be any vehicle damage. A speed breaker designed for two wheelers may be ineffective for trucks and a speed breaker designed for trucks may be dangerous for two-wheelers. - Safety. Even at high speeds, it should not cause a person too loose control. A lot of lives have been lost because of speed breakers - Maintenance. Over time the marking/paints will fade away. In which case there is a strong likelihood of some speed breakers not being repainted in time, causing accidents. A good design is one which need minimum maintenance. - Additional signage, which will warn the drivers of the speed-breaker. Again, one must take into account that the positioning of the signage may be improper or there may be too much clutter hiding the signage. Though signage is mandatory, design should not depend on the signage for safety. From left to right. A speed hump, cushion (split speed humps) and a table (whole intersection area is elevated). Different implementations have differing advantages. A
  23. 23. cushion theoretically can be avoided by a vehicle which is strictly aligned, thus necessitating slowing without the shock. A table can also be effective without much jerk to the vehicle but can be tougher to implement. Before laying a speed breaker, the pros and cons should be clearly thought about. Here are reasons one should not lay a speed breaker - There have been a number of serious accident and fatalities due to speed-breakers. - They can be painful to many people, especially people with medical conditions. Conditions of people with back problem can worsen. - They frequently cause damage to vehicles - They increase atmospheric pollution and decrease fuel efficiency. The slowing down and speeding of thousands of vehicles everyday adds up to cause major reductions in efficiency and thus increase in emissions. From an environment point of view, the best drive is the one at constant speed, whatever that is. - Create additional road maintenance headache. A badly maintained speed-breaker can be extremely dangerous. Once the designs are in place, and a municipal body plans to lay a speed breaker, the following should be thought through – - What is the purpose of the speed breaker. In case good road design practices are followed, there should not be a need for speed-breakers in the first place. Attempt should be made to see if a better road design can solve the problems being attempted to with speed breakers. (For eg: if it is a school area, giving wide footpath with barriers, signaled pedestrian crossings with refugee islands may be better than actually arbitrarily putting in a speed breaker) - Can other methods of traffic calming be used - What are the vehicles that will use this road and what speed do we need to restrict it too. - Based on the above, which design of speed breaker will be most appropriate Different types of speed breakers. Rumble strip on the left, an inverted U shaped in the centre and the flat top speed breaker on the right. b. Lane narrowing (Restriping, Neck down or chokers, Raised median islands)
  24. 24. There are many other methods of slowing down traffic, and one which can be used effectively is lane narrowing. In terms of effectiveness, speed-breakers are most effective; you just have to slow down. However, lane narrowing can be made to be fairly effective, without having the disadvantages of the former. Here, the different methods are classified as striping, neck-down or chokers and median islands. We will see each of these briefly. Restriping: The soft method of narrowing lanes. Least inconvenience to vehicles, however its effectiveness depends on compliance and that needs to be taken into account in the Indian context. Shoulder markings used to narrow travel lanes Painted center island and edgeline used to narrow lane Neck-down or chokers: This involves physically narrowing the road, by putting in obstructions at the sides. Figure shows lane narrowing achieved with signs9 In addition to humps, lane is narrowed. This results in necessary slowing down, without the need for large humps which would otherwise be a safety hazard.9
  25. 25. Figure shows how parking/landscaping to narrow lanes can result in traffic calming.9 Median islands: These are along the centre of the road, and can be of various forms, a couple of them are shown in the pictures below. Tubular channelizing markers used for center island to narrow lanes Signboard with raised platform for traffic calming.9 c. Pedestrian crossings The intention here is not so much to use pedestrian crossing to slow down traffic, but the placement of pedestrian crossings should taken into account the overall traffic pattern, in addition to the pedestrian needs themselves. In addition to helping pedestrians, it can assist improving the traffic flow as well, as shown in the picture below.
  26. 26. Figure shows a massive roundabout(below the flyover), but concept can be applied even to smaller roundabouts or other roads. As one can see, each entry and exit has a pedestrian crossing. This automatically acts as a traffic calming for vehicles using the roundabout. It regulates and balances the traffic, and the traffic can move in an orderly manner without the need for signals or explicit speed breakers. d. Visual modifications This is a soft method again, but can be effective. Gates or arches can give a feel that one is entering a residential area, a school campus or hospital. In fact these do exist, even if inadvertently and do make an impact on traffic calming. Figure shows how structures/ landscaping can give a clue of entry into a residential area, there resulting in more care by drivers. 9 e. Turns and twists, incomplete roads Speed can be picked up only on longer stretches of straight roads. A road which has a lot of turns or is wavy will automatically not allow fast traffic. For example, in residential layouts, long stretches of roads need to be avoided. The constant angles which come about will result in slower traffic, as well as heavy traffic avoiding those lanes. The above approaches need to be done during the planning stages itself and it is not possible to retrofit existing roads with these.
  27. 27. Left: In a pedestrian heavy area, route has been made narrow and torturous (number of twists and turns) for the purpose of traffic calming.9 Bottom: Top level view of inside of a residential layout in Bangalore. Straight roads end soon, number of T and staggered intersections and wavy roads all will result in slow and safe traffic within the layout. 5. Signage The purpose of this section is not to give the standard signs or details of what signage to use. These are already covered under IRC111 . It is rather to focus on when signage is required, what are required to be in the standards and where should they be placed. a. Need and what is required to be conveyed A sign is required when a sign is required. Absence of signage when critically needed such as one-ways, no right turn etc would end up in disaster. At the same time, care should be taken that signage is not redundant and unnecessary. “Follow traffic signs” is a classic example of unnecessary signage.
  28. 28. Figure on the left shows how a missing sign makes it potentially dangerous whereas the figure on the right shows a unnecessary sign. b. Clarity of meaning Figure on the left shows marking whose purpose is not clear. In an ideal scenario, a sign should be self explanatory without having to resort to language. Especially important in India, given the wide variety of languages spoken and written and the mix of people in every city. c. Standardization Figures above show the lack of standardization in signage. Standardization is a must to ensure compliance.
  29. 29. It goes without saying that signage needs to be standardized. In addition to the points that are mentioned elsewhere in this section, the following needs to be taken into account while standardizing signs. While creating standard signs, following should be specified i) Size and shape (should be clearly visible) ii) Colour coding iii) Placement (Location, Height of signage, distance with respect to what is being indicated) iv) Safety and ergonomics Signage with sharp corners protruding at shoulder height. Can potentially hurt cyclists and pedestrians. d. No clutter A very critical and often overlooked aspect of signage. When there is an excess of signage, they do not command respect. Hence, in addition to being judicious with road signs, it is important to minimize or reduce signage used by neighborhood shop owners, advertisement banners etc on the road. These need to be regulated, preferably they need to be clubbed together and placed in strategic locations, so that their needs are also satisfied without compromising on traffic safety. As an example, it is better to removing the no parking sign and instead use colour coded road side kerbs or alternatively painted stripes on the side of the road. The range is clear, does not clutter the driver visibility and is of interest only to those what want to park
  30. 30. 11+ signs in a few meters. Signage should be sparingly used, and where used, it should be ensured that there is a minimum of other signs. Clutter as in above would result in no sign getting attention. 6. Signaling 5.2 Static uses 5.2.1 Parking 2 wheeler parking 4 wheeler private parking 3 wheeler[rickshaw],Taxi and Para-transit parking 5.2.2 Hawkers 5.2.3 Bus-stops and transit facilities 1. Location • Conveniently located for pedestrians Unobstructed access to and from stop Preferably close to pedestrian crossing Should keep in mind that Q can build up beyond the stop itself and certain area should be kept free for passengers beyond the stop • Minimizes disturbance to regular flow of traffic.
  31. 31. Should not be so close to main junction so as to affect road safety or junction operation Should not be at the entry/exit ramp of a flyover as that creates unnecessary pile up Bus stops at the exit of the flyover can cause traffic on the flyover to back up as well as is dangerous for those on the side road seeking to enter the main road. • Clear of parking and other street furniture Dissuade other vehicles from parking near bus-stop area Should not have street furniture which would obstruct buses or bus-passengers accessing the bus-stop • Visibility Driver should get clear view of passenger Passengers should get clear view of approaching bus and its number/destination • Access to other bus-stops Should be situated to minimize walking distance between interchange stops Tail to tail, on opposite sides of the road, preferably with a pedestrian crossing between them.
  32. 32. For some reason, passengers on one side have to wait in the rain. Diagramatic representation shows where location of pedestrian crossing and new bus stop should be. Distance between bus-stops. Depending on locality, the distance should not be excessive (> 2 km) as this would burden passengers. Inside the city, where there is high population density, bus-stops should preferably be within 0.8 km. Similarly bus-stops should not be too close (< 0.4 km) as this would slow down the bus service. Wherever bus to different routes/destinations converge, it is better to bifurcate the bus-stop so that there is convenient boarding and alighting. 2. Information • Bus-numbers, bus-routes and bus timings Critical, but not done. Bus-stops should clearly have the bus numbers that stop at their stop, their routes and destinations and timing information. Bus-stop has most of the information, except bus timing. The bus stop name is hardly visible and the routing information needs to be made more easily readable and understandable. Name of bus-stop. Should be visible from the bus as well as from a distance for pedestrians
  33. 33. • Maps A city map which indicates all the bus routes and rational behind the bus numbering • Standardisation Above should be standardized, so that each bus-stop looks and feels identical. This will help quickly finding the relevant information for passengers. 3. Shelter design • Seating arrangement Are there adequate seating/standing berths depending on loading at that stop Is the seating arrangement easy to clean and maintain, given its heavy use It should facilitate the Q system. If there are multiple buses accessing a stop, it should be possible for passengers to access it without disturbing the Q system Incoming bus and number visible from where seated Protection from the elements, ie sun and rain • Box design aspects Should not obstruct pedestrian footpath Design should be such or placed such that the footpath is not obstructed/reduced or minimally altered Bus-stop on the left occupies the complete width of the footpath, forcing pedestrians onto the road (red circles). For narrow footpaths, bus-stop on the right maybe more appropriate, as it leaves ample space for pedestrians. Also notice litter bin (green). Entry/Exit should be facilitated Passengers entering the bus and those alighting from the bus should not conflict, with smooth movement of both
  34. 34. Prevent spillover to road We observe that passengers tend to spill over to the road and wait on the road. This results in the bus stopping away from the stop, further inconveniencing passengers in the stop. In addition, this takes a higher portion of the road, also makes it unsafe for the passengers. Design should take this aspect into account, and see if a barrier for spilling over into the road can be incorporated. Height of kerb While getting into the bus, if the kerb is at a height, this will facilitate entry to the bus. Also it will give a distinct flavour to the bus-stop. However, it will be effective only if the bus stops sufficiently close to the kerb Different ways of entry and exit from a bus. All need to be taken into account while deciding the critical dimensions as shown in the figure on bottom right. External aspects Lighting Well-lit bus stops are important for security purposes and identifying bus-stop Bus-stop signage and flag Identifying bus-stop from a distance. Enable bus to stop close (< 6”) Markings on the road to help driver identify and stop close to the bus- stop Cleanliness
  35. 35. Bus-stop and surroundings should be kept clean. A litter-bin to be placed if required. Clear marking (as in the right image) guides the bus driver and passengers for the bus to stop close to the stop. 4. Driver training All the above would not have the necessary impact if it is not supported by extensive driver training. Among the points the training should cover is Importance of stopping at bus-stops Ensure that drivers stop only at bus-stops and not at junctions or mid-road to pick up passengers How to approach bus-stops Important that the bus approaches the stop slowly and stops very close to the bus- stop such that the door aligns with the passenger entry. No overtaking at bus stops. If a bus is already present, the incoming bus should wait behind this. Minimize time spent at bus-stop Quick but safe entry and exit of passengers. The time saved at a bus-stop means less pile up of people and traffic, faster average speeds of the bus, thus lower travel times for passengers. If it could be calculated, there would be a significant economic value to lowering stoppage times. 5.2.4 Streetlights 5.3 Environmental functions 5.3.1 Trees
  36. 36. 5.3.2 Garbage bins 5.3.3 Rain water run off 5.4 Utility uses 5.4.1 Electricity 5.4.2 Water 5.4.3 Sewerage 5.4.4 Telephone cables 5.4.5 Internet cables 5.4.6 Cable TV 5.4.7 Others
  37. 37. 6. Design example Here we run through a real life example of a stretch of a road. We will look at the current state of this stretch of road, go through its uses as listed in section 4, and see the requirements of each of its uses as mentioned in section 5. Based on this, we will list out possible designs and explain how it will improve the road with respect to the objectives enumerated in section 2. …………. to be completed 7. Classification of Roads As we explained in section 3, it is impractical to go through the design process for every road. In addition, it is desired that there is a basic degree of standardization across all the roads in a city. To this end, we need to build design templates which can be then used at the construction of any new road that is being built. Given the variety of roads, there is a need to classify them depending on use and widths. The IRC2,7 classifies the roads as under: 1. Expressway: Function of expressways is to cater for movement of heavy volumes of motor traffic at high speeds. They are generally signal free by providing with grade separation at intersections. Parking, loading and unloading of goods and pedestrian traffic are not permitted on these roads. 2. Arterial: A general term denoting a street primarily for through traffic, usually on a continuous route 3. Sub-arterial: A general term denoting a street primarily for through traffic usually on a continuous route but offering somewhat lower level of traffic mobility than the arterial 4. Collector street: A street for collecting and distributing traffic from and to local streets and also for providing access to arterial streets 5. Local street: A street primarily for access to residence, business or other abutting property. The above is a good primary classification. In addition, the following should be used for further granularity 1. Width: Since the design and traffic capacity of a road depends on the width, this should be a necessary parameter while classifying the road. 2. Zone of use: That is, is this primarily in a residential, commercial or office area. Since usage patterns, parking, pedestrian requirements vary significantly between the above, this is also a necessary parameter while classifying a road 3. Special uses: For example, is this road supposed to support BRTS. Or does this support a cycle track. Again, since for these types, the design template will need to be specially done, they need to be included in the classification. So, as an example, one type of road based on this classification could be
  38. 38. Collector street, commercial, 24m width. This needs to be worked out so that almost all (at least 90%) of the roads in the city can be covered in this classification A similar approach and template designs are covered in IRC7. However, these reference designs are not comprehensive, and are primarily done only to give the desired width requirements. …………. to be completed 8. Design templates for each road type Based on the above classification, a number of road types were obtained in section 7. As mentioned in section 3, every class of road needs a template. Here we show example of one template – the utilities section has not been shown. 8.1 Template for 30m wide, sub-arterial road, mixed (commercial + office) with single cycle track Section view (bottom), plan (top right) and 3D view of the basic scheme of the road. The shoulder area can be occasionally used for car parking, hawkers, trees, greenery etc. Median area can be used as refuge islands for pedestrians and cyclists.
  39. 39. Left turns, Right turns and intersections. Storage lanes are created for turning which results in good throughput Bus=stops plan view and street view. Bus-shelter does not interfere with pedestrian area as well the bus stopping area is segregated from the normal lane traffic. Pedestrian crossing with refuge area between the opposite side bus shelters
  40. 40. …………. to be completed
  41. 41. Glossary Para-transit Pavement Roads Streets Verge …………. to be completed
  42. 42. References 1. Guidelines on regulation and control of mixed traffic in urban areas. IRC:70-1977 2. Geometric design standards for urban roads in plains. IRC:86-1983 [This document for cross-fall contradicts itself between section 6.2.5 (2.5% to 3%) and section 8.4 (3 to 4%). Ref 4 goes by max of 2.5% and we will go with the former guidance] 3. Guidelines for pedestrian facilities IRC:103-1988 4. Accessible bus-stop design guidance Bus Priority technical team advice note BP1/06, January 2006 Transport of London 5. Manual for streets Department of transport Thomas Telford publishing 6. Accesscode: a Code of Practice on Access and Mobility An advisory code reflecting current statutory requirement and best practice within the UK. 7. Space standards for roads in urban areas: IRC:69-1977 8. Guidelines for the design of at-grade intersections in rural and urban areas. IRC: Special publication 41-1994 9. Geometric design practices for European Roads – Context sensitive solutions. Study of European roads and road design practices by a US study group 10. Tentative guidelines on the provision of speed breakers for control of vehicular speeds on minor roads. IRC: 99-1988 11. Code of Practice for Road Signs. IRC: 67-1977 …………. to be completed
  43. 43. Appendix 1:Interesting links 1. A report on remaking new york streets. Tastefully done. 2. Excellent video on the New York street redesign – a must watch. The above site, ie has a lot of excellent videos one can go through. 3. Study of European roads and road design practices by a US study group 4. Council meeting in Albuquerque on speed-humps, interesting discussion, more so for the way it is carried out.
  44. 44. Appendix 2: Some useful dimensional information Vehicle dimensions (all dimensions in m) Maruti Hyundai Auto- Ambass Maruti Mahendra Tata Volvo Tata 800 Santro rickshaw ador Versa Bolero Safari Bus Truck Plus Length 3.335 3.565 2.625 4.325 3.675 4.44 4.650 12 9.01 Width 1.440 1.525 1.3 1.662 1.475 1.66 1.918 2.5 2.44 Height 1.405 1.59 1.71 1.593 1.905 1.977 1.925 3.52 Wheelbase 2.175 2.38 2.0 2.464 2.35 2.794 2.650 6.2 Front Track 1.215 1.28 Rear Track 1.2 1.29 Minimum 4.4 4.4 2.88 5.4 4.5 5.9 6.0 11.5 11 turning radius Ground clearance 0.17 0.17 0.18 0.195 0.205 2 Wheelers Motorcycle: Hero Honda Motorcycle: Bajaj Pulsar Motorcycle: Yezdi Scooter: Bajaj