Safety in Construction, Operations and Maintenance of Highways – Basic Elements of Safety Audit
In the recent past, in India too, with the rapid economic growth in the country, the demand for better facilities and infrastructure has increased. The road system is now getting new attention. Improved roads resulting from a better designed and execution would lead to increased speed, better safety at high speed to meet the enhanced aspirations as well as indulgence of the people for a safe and efficient movement.
IntroductionRoad improvement in the country has been taken up on a large scale with the launching of National Highway Development Project (NHDP)/ National Highway Authority of India under its various phases and State Governments are having their own programmes for improvement of state roads. It has been found that though signs and markings are provided on these improved roads, but they are still far from being the appropriate system to meet the intended requirements of safe and efficient travel. Now that the objective is to develop the National Highway System to a world class standard, it is essential that all the roads including those which are under improvement / upgradation are provided with a detailed system of traffic signs and pavement markings.
- Fulfill-specific needs as per the site situation;
- command attention from all categories of road users;
- convey a clear, precise meaning in a simple form;
- command respect from road users and for this, they should be appropriately sited, visible/ readable and uniform throughout;
- placement should give adequate response time for a proper response;
- conspicuous to attract attention of the drivers and should be legible from sufficiently far away to be read without diverting the line of sight through too great an angle; and
- placed such that they are not obscured by other objects or vegetation and no clustering has taken place;
- road markings should be clear and visible during the hours of darkness (luminous/ reflective) so that drivers can see them clearly in time to position themselves correctly.
The guiding principles for safety measures shall include:
- Warning to the drivers unambiguously and sufficiently in advance of the situation on the highway;
- Providing clear demarcation for movement of vehicles;
- Providing devices to guide the drivers and their movements through construction zones/ lane closures/ traffic diversions etc.
Construction ZoneIn order to plan and provide appropriate traffic management and safety measures, it is necessary to appreciate the concept of a construction zone. A construction zone can be defined as an area of the Project Highway which involves the conflict of the right of use between the road users and authority responsible for the maintenance/ improvement of the Project Highway. From traffic safety point of view, a construction zone comprises four sub zones as described hereunder:
- Advance Warning Sub-Zone: The advance warning sub-zone is meant to prepare the driver for an alert behavior and is an essential part of any traffic control system.
- Transition Sub-Zone: The transition sub-zone is the area in which the traffic is steered and guided into and out of the diverted path around the work sub-zone. This is the most crucial sub-zone from safety point of view since most of the movements are turning movements.
- Work Sub-Zone: This is the actual area where construction or maintenance activity is taking place and the main concern, therefore, is the safety of the workers at the site from the plying traffic. The path of the traffic must, therefore, be very clearly delineated to avoid intrusion of vehicles moving into the work area. The work sub-zones shall not be close to each other and the distance between the two work sub-zones shall be such that the flow of traffic can return to normal stream by permitting fast moving traffic to overtake slow moving vehicles. These distances shall preferably be 2 km on urban sections and 5 to 10 km on rural sections of the highway. The length of work sub-zones will vary.
- Termination Sub-Zone. The sub-zone is intended to inform the road users of the end of the construction zone. An information signboard shall be erected to inform road users of the end of construction Zone.
Traffic Management Planning
- Warn the road user clearly and sufficiently in advance.
- Provide safe and clearly marked lanes for guiding users.
- Provide safe and clearly marked buffer and work zones.
- Provide adequate measures that control driver behaviour through construction zones
Traffic Control Plan for a specific project should be prepared and applying the following variables, which may vary from project to project. The variables are,
- Average Vehicular Traffic Density in peak and non-peak hours.
- Maximum width of lane required for construction during various activities.
- Number and types of junctions in the road.
- Availability of standard footpath and its location and dimensions.
- Change in the lane width if any and its location.
Traffic control devices used to regulate the traffic in Road Construction Zones include:
- Road Signs
- Pavement markings
- Flashing lights.
- Mandatory / Regulatory Signs These signs impose legal restriction on traffic and violation of these signs is an offence. These include all signs, which give notice of special obligations, prohibitions or restrictions with which the road users must comply. Regulatory signs are mostly circular in shape.
- Cautionary / Warning Signs These signs are used to warn road users of the existence of certain hazardous conditions either on or adjacent to the roadway, so that the motorists are cautious and take the desired action. Cautionary signs are triangular with red border and black symbol or message on white background.
- Informatory Signs These signs are used to guide road users along routes, inform them about destination and distance, identify points of geographical and historical interest, and provide other information that will make the road travel easier, safe and pleasant. They are usually rectangular in shape.
The traffic across these sub-zones is guided and taken with the help of various traffic control devices erected at the site
2. Delineators. Delineators are devices or treatment which outlines the roadway or portion thereof. They include Safety Cones, Traffic Cylinders, Tapes, Drums, Painted lines, Raised Pavement Markers, Guide Posts, and Post-mounted Reflectors etc. They are used in or adjacent to the roadway to control the flow of traffic. Delineators are basically driving aids and should not be regarded as a substitute for warning signs or barriers for out-of-control vehicles.
3. Barricades. Barricades are intended to provide containment without significant deflection or deformation under impact and to redirect errant vehicles along the barrier. Barricades can be used to:
- Prevent traffic from entering work areas, such as excavation, material storage area.
- Provide protection to workers.
- Separate two-way traffic.
- Protect construction such as false work for culverts and other exposed objects.
Barricades can be permanent or portable. Portable barricades should be stable under adverse weather conditions and appear substantial but not so much as to cause excessive damage if a vehicle strikes.
Three types of typical barricades generally used in road construction zones, with recommended dimensions are given below.
Type I And Type II Barricade
These barricades shall be used when traffic is redirected in a road. These barricades can be used interchangeably and more suitable for repair, maintenance and other temporary works. As these barricades are susceptible to overturning in wind, their stability can be improved through ballast.
Type III Barricade
This is a permanent type barricade and can be erected at the point of closure when a road section is closed to traffic for construction works. They may extend completely across a road way and its shoulders or from kerb to kerb with a small gate or movable section for the entry of construction workmen and vehicle.
4. Safety Cones. Safety cones are 500 mm, 750 mm and 1000 mm high and 300 mm to 500 mm in diameter. They are usually made of plastic, rubber, HDPE, PVC and have retro reflectorised red and white bands. Safety cones would be displaced or blown unless their bases are anchored or loaded with ballast. This can be avoided by
- Using sand bag rings to provide increased stability,
- Using heavier weighted cones,
- Using cones with special weighted bases, and
- Doubling the cones to provide added weight.
- A qualified personnel at least average intelligence, be mentally alert and good in physical condition be selected, since flagmen are responsible for public and workmen safety.
- Flagmen should be equipped with yellow helmet with green reflective sticker fixed around and reflective jacket along with hand signaling devices such as flags and sign paddles. The typical specification are given below.
Red Flag – Minimum size 600 X 600 mm (Polyester cloth advisable) securely fastened to a staff of length approx. 1 m
STOP Sign Paddle – Shape - Octagonal (Light in weight) Width - 600 mm with rigid handle Background Color – Red, Letter Color – White
SLOW Sign Paddle – Shape - Octagonal (Light in weight) Width - 600 mm with rigid handle
Background Color – Yellow, Letter Color – Black Border Color–Black.
- Flagmen need to maintain the flow of traffic continuous past a work zone at relatively reduced speeds by suitably regulating the traffic. He shall stop the traffic for a short while whenever required (e.g. for entry and exit of construction equipment in to work zone).
- Flagman should be positioned in a place where he is clearly visible to approaching traffic and at a sufficient distance to enable the drivers to respond for his flagging instructions. A flagman never leaves his post until properly relieved,
- The standard distance shall be maintained at 60 – 100 m but can be altered depending upon the approach speed and site conditions. In urban areas this distance shall be taken as 20 m to 50 m.
- Standard Signals to be given by Flag men and they should undergo special task training program through safety department.
Safety Measures During Concession Period
- During the Concession Period or extension thereof as per the Concession Agreement many activities are involved at different stages and at various periods in respect of construction, operation and maintenance of the Project Highway. Safety of the road users and the Project workmen at site is of paramount importance and obligatory for the Concessionaire throughout the said period.
- In Emergency arising on account of Force Majeure due to nature or administrative reasons special safety measures may be called for the traffic and/or the workmen at site to be taken by the Concessionaire.
- The following principles shall be kept in view in Emergency situations from safety considerations:
- Where part width of the existing carriageway is envisaged to be used for passage of two way traffic, paved shoulders shall be used on the side on which work is not proposed. A maximum of one lane (3.5 m wide) closure shall be allowed for a short duration depending on the extent on Emergency.
- At the points where traffic is to deviate from its normal path, the channel for traffic shall be clearly marked with the aid of pavement markings or other similar device as directed by the Independent Consultant. At night the passage shall be delineated with lamps or lanterns or any suitable light source.
- On the approach of any type of closure suitable regulatory/warning signs as approved by the Independent Consultant shall be installed for guidance of road users. At least two signs shall be put up one lose to the carriageway where transition of carriageway begins and the other 120 m ahead. The signs shall be of approved design and of reflectory type as directed by Independent Consultant.
- The Concessionaire shall ensure that safety standards specified in this Schedule are strictly complied with in the event of any lane closure or diversion of traffic.
Highway Safety Audit (HAS)Highway Safety Audit is a systemic evaluation process for highway construction, operation and maintenance safety, which introduces concepts of highway operation safety and reduction of traffic accident into the feasibility study and design of highway project. It is a basic procedure in highway construction and management.
Before 1980s, such measures as warning signs, speed limit and re-alignment, etc. were adopted by many countries in the world to reduce traffic accident during operation period. Results were encouraging but the problem would be solved gradually and take a long time to avoid/ limit large losses of staff and properties. If potential factors in highway facilities, which would influence traffic safety, could be found and corrected before traffic accident, during planning, study and design period of highway facilities, losses of staff and properties would be substantially reduced. Concepts and approaches for HSA have evolved gradually under such background. Around 1985, the United Kingdom started to study and spread HAS technologies and regulated that HSA be carried out for all new expressway and motorway. After 1992, the study and application of HSA were carried out in Australia, New Zealand, Malaysia, Denmark and Netherlands, etc. America started road safety study earlier. In 1967, AASHTO published "Highway Design and Operation Practice Considering Highway Safety," which was modified, extended and re-published in 1974. From 1985, Highway Safety Information System was established to accumulate traffic accident data. From 1990, theoretical study for HSA was started and important outcomes were achieved, forming AASHTO Criteria in 1991, "Guideline for Road Safety Design and Operation." In 1997, AASHTO published the updated version of this Guideline. Furthermore, in 2003, it put forward Roadside Safety Analysis Program (RSAP) and Interactive Highway Safety Design Model (IHSDM), pushing the HSA from qualitative analysis to combination of qualitative analysis with quantitative analysis.
In countries which have conducted HSA, the evaluation stages are generally divided into five stages, namely:
- Feasibility study,
- Preliminary design,
- Detail design,
- Trial operation, and
Division of highway infrastructure phases and contents and depth of each phase in China are different from other countries and the study of HSA has just started. Therefore, preliminarily, there are three evaluation stages - feasibility study stage, design stage and operation stage. Evaluations in feasibility study and design stages shall be completed before official approval for the project highway by relevant governmental departments. Evaluation in operation stage shall be completed before inspection and approval of the project highway.
HSA shall be carried out by independent third party to realize objective and fair evaluation. Usually, the evaluation work shall be entrusted and coordinated by Project Legal Person.
Audit Parameters of Road Safety
- Components of the Construction Zone
- Sketches at cross-sections
- Roadside communities & Facilities
- Stretches at junction
- additional checks for roundabouts
- additional checks for signal-controlled junctions
- Special road users
- Road side hazards
Refer: Sample List for Audit Component
Disclaimer: The author does not claim the sole credit for the entire text of the article since concepts and context of the content are in the common knowledge domain and therefore have been quoted to substantiate a point. Any semblance/ replication of some earlier publication is purely inadvert. In any case, the author’s thanks are due to such publishers/ authors.
- Prevent traffic from entering work areas, such as excavation, material storage area.