How To...

How to manage site traffic safety

Site traffic safety is often among the highest risks on site, due to exposure frequency and severity of the potential consequences.

Traffic management plans are often found in health and safety plan requirements, yet some project managers and facilities mangers pay little attention to the legal aspects of site traffic, writes NIOCCSA OHS specialist Rudy Maritz.

Some roadwork sites are fatal or serious injury incidents waiting to happen. If the project is to be constructed ‘under traffic’, this requires meticulous planning, engineering and signage to ensure the safety of workers, the public, and plant.

Sites with groundwork or excavations, moving machinery of different sizes, construction, heavy vehicles such as agriculture or logistics, blind corners such as grid-based plants, high pedestrian volume such as campuses, hazardous materials, dust, fumes or vapours, and loose gravel, or short transitions from site to public roads, present particular traffic risks.

The South African Road Traffic Signs Manual, Volume 2, Chapter 13, sets standards for planning, design and implementation of temporary road works and traffic interventions.

Pre-construction traffic planning

Different phasing options should be considered and any features of the project that require special traffic management during the construction phases should be identified, such as off-loading of materials with tipper trucks, waste skips, and so on.

The SARTSM Manual gives detailed sample drawings of the various types of road works. The general site is divided into five areas, as discussed below.

1 Advanced warning area

Motorists travelling at 120 km/h are moving at a speed of 33.3 meters per second. The average motorist takes a full second to react to visual observations in the road; it takes 33 meters to see something and react to it. A flagman in the road 30 meters away from a closed lane could be killed before the driver can react.

Advanced warning areas are designed to warn motorists of approaching changes in the road and the length of the advanced warning will depend on the speed (not speed limit) of the road being travelled on.

It is important to send messages to the approaching traffic via road signs. First is to warn them of approaching road works using a sign numbered TW336 commonly referred to as a men-at-work sign that looks like a man trying to lift a very heavy umbrella.

Next you need to reduce the speed of the on-coming traffic, and inform them what is to happen. Either the road will narrow from the left or right, or they need to change direction into a detour, or there is a stop-go ahead.

It is also advisable to warn them on which side of the road they can expect the road works. Using flagmen to wave the traffic down is also an effective means to reduce travelling speed.

2 Transition area

Immediately after the advanced warning area, comes the first intervention. This could be a lane closure, a detour, or a full or partial lane drop.

It is important that the motorist knows this before entering into the second phase, or the “transition zone”. For example, in a three lane road, you first need to close the left lane, allowing motorists to move from the left lane into the middle lane. That is your first transition.

3 Stabilising Area

The next step is a stabilising zone where the cars are allowed to travel in two lanes before you deviate them a second time with another transition area. You would now have three lanes of traffic diverted into one lane and approaching the work zone where your team is busy.

4 Safety buffer

For the safety of your teams it is advisable to allow for a buffer zone ahead of your work area. The buffer zone is created by leaving sufficient space before your work area.

On high speed roads it is advisable to position a vehicle in the work zone between on-coming traffic and the work team to absorb the impact of any stray motor vehicles. These vehicles should be fitted with high visibility chevrons and amber flashing lights.

5 Work zone

The work zone is where you are actually busy with your work, be that an excavation for a new storm water pipeline or mowing the lawn in the road reserve.

Normalisation area

After your work zone you could set up a normalisation area, where traffic flow is restored to normal, the speed reduction removed, and a Thank-you message displayed. The length of each zone depends on;
1. travelling speed on the road
2. direction of the road in relation to sunrise and sunset in season
3. stopping sight distance
4. width of the roadway
5. road surface, tarred or gravel, and condition.

In planning construction traffic safety management, also consider these aspects;
• bypasses or temporary widening
• pedestrian or cycle traffic access
• maintaining the minimum allowable lane width
• reduced work zone speed limit
• types of vehicles to be prohibited from entering the work zone (over-height, weight restriction).

Timing of roadworks

Consider these timing elements;
• peak hours
• one or both directions
• overnight
• holidays or weekends
• sporting or other events
• other construction projects in the immediate areas
• would restrictions reduce the road safety performance of the construction site?

Special safety precautions may be needed in these instances:
• pedestrians or cyclists
• school areas and crossings
• playgrounds and parks
• Visually impaired persons

Construction traffic emergency response
One of the most over-looked aspects of traffic management, is the dreadful time when things go seriously wrong.

Provision should be made for standby towing service, emergency lay-byes and planned detour routes in case of an accident.

Work zone ITS strategies like CCTV monitoring should be considered for traffic monitoring. Local road traffic police should be consulted with a view on possible law enforcement within the work zone, but in any event, the local authority should sign off on the proposed layout of the traffic management plan.

Local radio stations should be advised of the construction in order for road users to be advised of the need to consider alternative routes.

In cases of construction projects of extensive duration, a public information meeting may be required.

Traffic risk management

As the controlled area falls within the control of the contractor appointed for the works, the liability for legal compliance and due care applies to the entire road, from the first to the last road sign.

Quick and effective response to any changing conditions should be catered for within the shortest possible time frame.

Here are some DON’Ts in traffic management;
1. no traffic signs in the roadway, place them on the sidewalk or shoulder
2. no securing with bricks, stones or rocks; use sand bags
3. no cones, use delineators instead, they indicate direction
4. no flags to untrained people,– flagman training is available
5. no other functions or distractions, keep focussed
6. never stop the flow of the traffic, unless at a stop ‘n go
7. never start work before you have set up all the signs according to SARTSM requirements. If it confuses you, it will confuse motorists too.

Road terminology

The National Road Traffic Act defines the various parts of a road as follows:

“edge of the roadway” means the boundary between the roadway and the shoulder, which is indicated by an appropriate road traffic sign, or in the absence of such sign –
a) in the case of a road with a bituminous or concrete surface, the edge of such surface; or
b) in the case of any other road, the edge of the improved part of the road intended for vehicular use.

“kerb line” means the boundary between the shoulder and the verge or, in the absence of a shoulder, the part between the edge of the roadway and the verge

“roadway” means that portion of a road, street or thoroughfare improved, constructed or intended for vehicular traffic which is between the edges of the roadway

“shoulder” means that portion of a road, street or thoroughfare between the edge of the roadway and the kerb line

“sidewalk” means that portion of a verge intended for the exclusive use of pedestrians

“verge” means that portion of a road, street or thoroughfare, including the sidewalk, which is not the roadway or the shoulder.

Safe site management!

Rudy Maritz is the National Institute of Occupational Compliance Consulting of SA (NIOCCSA) OHS specialist.

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