Monday , 25 January 2021

Road Traffic Control and Safety Devices – Where we need to improve

Manoj Tipnis, Vice President & Head Engineering
Suvra Chakrabarti, Senior Manager & Head – Roads Traffic & Safety Engineering

For smooth and safe road travel, it is recommended that the relevant Codes by the Government are reviewed periodically and updated as required to keep the codes relevant with international best practices and evolving transportation scenario. It is also important to provide a superior quality infrastructure and uniform traffic control devices. Some important aspects and views on the present status are expressed in this article by Manoj Tipnis, Vice President & Head Engineering and Suvra Chakrabarti, Senior Manager & Head – Roads Traffic & Safety Engineering, both from L&T – Transportation Infrastructure IC – RREC

Imagine driving through a network of busy and winding streets with cluttered frontage dotted with multiple signs and advertisements. Traffic signs are hidden somewhere in that visual clutter. Finding the signs while driving makes their placement simply ineffective. In absence of any effective signage guiding towards one’s destination, one incorrect turn may even lead to an entry ramp of an urban high-speed corridor that could lead straight towards downtown; the nearest exit or u-turn for course correction lying at least five kilometers away. What would a responsible driver do?

Here is another situation where motorists are negotiating a stretch of a wide road with absolutely no lane delineation with markings and studs. It can potentially be dangerous since lane change maneuvers are not guided by any lane marking. This situation would worsen during night time and inclement weather conditions like rain and fog when visibility is low. What would a responsible driver do in this case?

The most desired situation would be to provide a superior quality infrastructure and uniform traffic control devices for travel on high speed urban roads or highways.

Traveling in this heterogeneous environment in countries like India requires undivided attention, concentration and focus for safety. Therefore, the basic expectation of any driver/road user is to fully trust the infrastructure provided to the drivers in terms of traffic control and safety devices without any room for doubt. Any surprise element thrown in this mix could distract drivers and could therefore potentially lead to accidents. While speed differential, distracted driving and driving under influence of alcohol remain the major causes of road accidents, there is a crucial role of traffic control and safety devices that can prevent many accidents. Intangible benefits of better facilities would be improved concentration of drivers, lesser fatigue to drivers, fewer road rage incidents and a more pleasant ride and experience for road users generally.

Despite having the best intention of providing user-friendly infrastructure, chances are they could still be inadequate if careful consideration is not given. In the examples mentioned at the beginning, a responsible driver will drive up to the next exit or u-turning location where it is safe to turn back. However, even if one driver decides to disregard the traffic control devices & safety arrangements and makes a u-turn sooner, then he would endanger multiple vehicles and lives. In the second example, a responsible driver would drive within speed limit, check the blind spots and change lanes or weave after giving adequate indication using indicator lights of the vehicle. Constant weaving action, high speed and not checking the blind spots will create safety hazard.

Accuracy of Codes

Every country has its own rules, standards and practices when it comes to the traffic control and safety devices. Indian rules are based on the Motor Vehicles Act along with many principles from various international standards. However, non accuracy of code clauses, their interpretation, anomalies in implementation and lack of maintenance are hindrances that require careful consideration and incorporation.

Codes specifying standards of signs, markings, etc. are the holy grail for practicing engineers since authorities and governing bodies that own the roadway systems benchmark their roadway and related infrastructure based on the codes. Therefore, clauses specified in the codes are considered law of the land and are revered by the design engineers. These are the rules and regulations based on which facilities are planned and designed. Accuracy and precision are key parameters of codes and clauses.

Clauses are based on principles of physics and mathematics and sometimes, based on studies of driver behaviour and empirical formulae. Some clauses are derived from International standards to introduce international best practices in the county. Accuracy of clauses of codes and its various applications and references in various other codes are of paramount importance.

All road users have priority assigned to them; generally termed as right-of-way. In case of vehicles arriving at junctions (intersections), incoming vehicles must have undisputed priority so as to avoid any confusion as the vehicles negotiate the junction safely. In this context, the universal “Stop” sign and “Yield” or “Give Way” signs are not just any simple signs. These signs are used for assigning right-of-way or priority to road users and should not be used indiscriminately. IRC:67, which is the ‘Code of Practice for Road Signs’ should present warrants to determine whether a junction arm shall be stop-controlled or give-way controlled; i.e. whether vehicles from all / select incoming arms of a junction shall come to a complete stop or, slow down at the junction mouth and then proceed through the junction. Therefore, it is not just a matter of placing a stop sign or a give-way sign to satisfy the codal provisions. It needs careful consideration and detailed warrant analysis to decide which sign to place where and why.

Warrants are currently not presented in IRC. Warrants could be as prescribed in the Manual on Uniform Traffic Control Devices (MUTCD) of the United States of America. For high speed corridors, the location and selection of stop or give-way sign may seem intuitive, i.e. place the control signs on the connecting roads or cross roads. However, this decision becomes more crucial in case of more complicated roadway network such as a city’s grid of roadways where many cross roads may have equal importance. Choice of the correct sign becomes even more crucial in such cases.

As a safety device, the role of crash barriers are indisputable. Metal beam crash barrier specifications are presented in IRC:119 ‘Guidelines for Traffic Safety Barriers’ and those are also published in various highway and expressway manuals. Subsequently, the Ministry published circulars wherein further clauses are specified. In case of metal beam crash barrier, the general arrangement drawings provided in the codes are regarded by the authorities as the ultimate arrangement that requires exact replication on ground. Whereas, crash testing to American or European standards are specified as mandatory requirement elsewhere in the codes and circulars. A metal beam crash barrier system following the general arrangement may not satisfy the crash testing as per the stipulated standards. Therefore, clauses are conflicting within the same code. Furthermore, an infrastructure project requires approach and departure end terminals and transition to concrete crash barrier in many instances. The codes need to developed sufficiently to address the design and crash testing specifications of these items.

Let us take the example of road studs or cat eyes as we know it more commonly. Its specifications are provided in the highway and expressway manuals and also in IRC:35, which is the ‘Code of Practice for Road Markings’. There is a clear conflict between the two sets of codes. The highway and expressway manuals call for studs only at select locations; whereas, the marking code calls for studs all over the roadway with varying spacings. This is a clear conflict across various codes because a construction project’s contract typically specifies both codes to be followed. The Contractor and even the authority have a dilemma as to which one to follow. Generally, more conventional one can be followed for added safety. In that case, we need to ask ourselves, will placing studs all over the roadway make it really more effective? At locations where drivers need to be more aware or cautious, say at a sharp curve or approaching structures – providing studs makes sense from a driver’s perspective. However, providing studs all throughout the roadway with slightly shorter spacing at hazardous locations may not have the same effectiveness to a driver as the shorter spacing may not be perceptible to the driver. In the case of studs in the transverse direction, spacing of studs in a single line is not specified, which is an incorrect specification and it is open to interpretation by different agencies.

Pedestrian facilities requirement is somewhat broadly outlined in IRC:103 ‘Guidelines for Pedestrian Facilities’. However, this is not so in other IRC codes that are considered as manuals for various
road construction projects’ contract specifications. Cross-referencing of
codes makes the scope very vague and on many occasions, it is up to the authority’s discretion at the very last stage of the project. This can delay the project resulting in increased project cost and also inadequate facilities for the end user.

Pedestrian facilities ideally shall have a well-thought-out strategy to provide the last mile connectivity and not just a patch of footpath here or, a few zebra crossings there. It shall have a continuous connectivity from the connecting modes of travel (say a bus stop) to the nearest junctions leading to a locality for example. It shall have wide footpath with accessible ramps, tactile paver blocks for equitable access, pedestrian crosswalks, pedestrian guardrails or, handrails, bollards, adequate lighting, refuge areas and seating arrangement, wherever required. Furthermore, IRC implies many pedestrian facilities are to be provided in urban locations. However, even if a project is defined as rural highway project then these facilities are still required to be provided wherever pedestrians are expected to use the roadways.

Many of these points and terms are not clearly defined as mandatory requirements under the scope of a construction contract as the relevant contract clauses are generally not well-developed. Such clauses do not state mandatory conditions assertively; therefore, the scope remains vague. Circulars released by the Ministry at various points of time are not collated into a code and many times the provisions are unknown or overlooked. As a country where pedestrian volume on road network is quite large, it must be looked into much closely and carefully so that the new facilities and infrastructure are pedestrian friendly and existing facilities are retrofitted to accommodate the pedestrians’ basic need of safe and equitable access. Many other road safety items such as traffic impact attenuators, noise barriers, antiglare devices, solar blinkers, etc. are not clearly specified in IRC. Many of these items are dependent on manufacturers’ specifications. The same could be collated and presented as guidelines so that there is a baseline availableto Civil Engineers.

Interpretation of Codes
Codal language and applications must be definitive and must not leave any room for any guesswork and misinterpretation. Application of the same clause shall not vary from agency to agency in charge of implementation.

A very important aspect of Indian codes is that the requirement and specifications for various types of signs are laid out in various codes. For
example, the four-laning, six-laning and expressway manuals also have specific signage placement schemes for respective roadway types, which is a good idea theoretically. However, discrepancies across various codes create confusion. For example; Chevron signs are very useful for
drivers by virtue of its simplicity and placement. The simple arrowhead
symbol quickly gives a sense of oncoming change in direction to the driver so they can negotiate the curve effortlessly. These signs shall always be placed on the outer side of horizontal curves at spacings dictated by the radius of curvature of the curve. The same sign becomes quite a hazard if placed on the inner side of the curve or if the arrowheads are wrongly positioned or if the spacings are changed. In this context, IRC:67 and the other manuals have slightly different spacings. Ideally the spacing shall be consistent across codes such that there is no ambiguity while designing and the drivers also experience uniform information.

Another pertinent example is the specification of signposts across various codes. IRC:67 and other codes specify the use of GI posts for mounting of signs. Relevant clauses in these codes do not specify crashworthiness or frangibility of such posts. However, IRC requires the signposts to be frangible breakaway type elsewhere in the manuals of standards and specifications without furnishing any further detail about it. Its sole mention is in the section for crash barrier specifications. All signposts shall have adequate lateral clearance from live traffic lanes as specified in IRC. Further, signposts shall be guarded by crash-tested crash barriers in front. Therefore, the requirement for frangibility of signposts is simply an infructuous specification. Furthermore, frangibility of posts is a new concept in India as far as its implementation is concerned. Manufacturers may find it difficult to provide this type of posts as there is no standard clause in India. This can lead to confusion among the implementation agencies and authorities. Whereas, international standards specify further details and furnish examples of the products, including their crash tests to give a more detailed picture such as the European and American standards.

In the changing transportation scenario of India, long stretches of high-speed corridors are being constructed with design speed of 150 Kmph eg; the Mumbai-Nagpur expressway, whereas the IRC codes specify standards for the traffic control and safety devices for only up to 100-120 Kmph and imply the use of the same standards for any speed greater than 120 Kmph. However, the codes must specify the correct dimensions and other specifications that are applicable for 150 Kmph definitively. Otherwise, various agencies will interpret the clauses differently and provide nonstandard or, sub-standard products not effective for high-speed corridors.

A simple consequence in this context is the font size of text on direction sign boards play a crucial role. Font size calculation remains a tedious task combining principles of older and the most-recent IRC:67. Complete methodology is not available in any single code. Furthermore, even if the font height can be derived from first principles after referring to multiple versions of the code, the width calculation is not available in IRC for higher speeds and that remains a variable and it is up to the signage manufacturing agency to calculate. This is again a subjective treatment of a very specific element that should be standardized throughout the country as it is easier for motorists to understand and interpret the signs quickly if they are uniform.

Anomaly of Implementation of Traffic Control Devices and Lack of Maintenance
After all this comes the anomaly of implementation. For example- if a crash barrier is placed without any room for deflection of the vehicles then it will not serve its purpose of deflecting the errant vehicle to its original path. If an overhead sign, which is meant to provide advance guidance before a flyover is placed too close to the flyover then vehicles that do not intend to use the driver will not have enough reaction time to make an exit decision.

Maintenance of the control and safety devices also play a major role. Markings, studs, kerb paintings and shoulder-mounted signs get covered in dust and dirt quite easily. Regular cleaning, repairing, and replacing are a must to keep the devices in their desired useful condition. This requires condition checking regularly by the owners of the roadways or local authorities. This also requires protection from vandalism and theft This important step of a project’s life cycle often gets overlooked or omitted due to inadequate funding, resources, and awareness. A faded overhead sign board that has no retro-reflectivity left, will not provide any guidance to an oncoming vehicle that needs urgent information for decision making. Similarly, faded roadway marking, broken crash barrier or stolen handrails will diminish the effectiveness of traffic control and safety devices intended for optimal use of the roadway.

At the time of implementation, many adjustments are made in the final roadway and junction arrangement to suit local needs and satisfy requirements of influential individuals superseding IRC provisions. For example, a business unit may require a median opening right in front of its business, which might violate the clause regarding median opening spacing or other pertinent clauses like distance of median opening/u-turning facility relative to an entry/exit ramp, etc. Such deviations at the whim of local interests are extremely dangerous to road safety and be strictly avoided.

Newer Technology
More sophisticated features are being added in vehicles to make them better and safer. New technologies such as GPS based map apps, rear cameras, sensors and communication devices have made driving easier and safer than before. With newer technology, drivers may be tempted to think that they are safe, but to keep them truly safe, the entire driving environment needs to be forgiving and road user friendly. Traffic control and safety devices make the driving environment safe along with vehicles, drivers’ and other road users’ behavior and overall road infrastructure. This can be achieved with correct specifications in codes, their correct interpretation and implementation.

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