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This document will cover managing traffic flow through a work zone. Construction, maintenance, utilities workers, landscaping, emergency workers, and all other occupations who may conduct activities on or along the road are exposed to hazards such as:
Traffic control refers to the use of temporary traffic control devices to protect workers and to move road users safely through a work zone. A traffic management plan is usually required to outline the traffic hazards, and to specify the measures needed for traffic control. Health and safety legislation focuses on safety requirements including increased visibility of the workers, signage, and signaling.
A general approach to traffic control is discussed in this document. Always consult with your jurisdiction for specific requirements.
A traffic management plan is usually required to outline the traffic hazards, and specify the measures needed for traffic control. A traffic management plan can be defined as: “the strategies designed to safely mitigate the impact of construction, rehabilitation, maintenance, incident management and special events on roadways to maintain mobility and worker safety.” (From: British Columbia Ministry of Transportation and Infrastructure).
Plan the traffic diversion so that the flow of traffic ensures the safety of the workers, and the road work does not endanger the other road users.
Plan the traffic diversion in the work zone to take into account:
The traffic management plan should include:
Traffic control is managed through three systems:
Where ever possible, the hierarchy of controls (using elimination/engineering/administrative/personal protective equipment) should be used.
Elimination Controls: Ideally, the elimination of the hazards should start at the design phase by considering structures, materials, processes, and measures that would allow for minimal and safe maintenance. Alternatively, when planning a work activity that would close part of the road, consider if it is possible to close the road completely. Are alternate routes available?
Engineering Controls: If total closure is not possible, develop a written traffic management plan. Try coordinate road work with other necessary works (e.g., tree clearing) to minimize the length of time the road is obstructed. Use barriers or other devices to channel traffic, and, where possible, provide a physical separation between the work zone and passing traffic.
Administrative controls: If possible, plan most of the work during non-peak hours or night time when the traffic is light.
Appoint a competent supervisor to establish and monitor the work zone. Communicate the plan to the workers, and train the workers who will work, set up, install, and remove the signals or barriers in the area. Attention must be given to the set up and installation phase since those workers will be exposed at an increased risk of injury.
Personal Protective Equipment: Workers wear high visibility clothing as appropriate for the situation and time of day/night.
When work is conducted on the road, the work zone is not limited only to the area where the actual work is done, but extends to all areas where devices that guide the traffic are used.
A typical layout for a temporary work zone has the following sections:
Depending on the extent of the work and the road type, the requirements for each area will vary. Check the requirements in your jurisdiction for detailed information on the layout requirements for different situations. The figure below illustrates a sample layout for a lane closure with traffic control persons on a two-lane two-way road.
Figure 1: Lane closure with traffic control persons on a two-lane two-way roadway
When setting up the work zone:
When traffic control persons are required, workers should only direct traffic from one lane in the same direction. This person must:
The equipment used to ensure safety in the work zone can be grouped in three categories: warning or information, closure/guidance, and protection.
Warning/information includes items such as fixed or mobile gantry signs, or temporary rumble strips.
Closure/guidance includes items such as traffic cones, drums and barricades.
The cones and barrels guide the traffic, but cannot protect the workers against collision. The spacing between the cones or drums can vary and depends on the type of work and the speed of the road. Place cones, etc. so that there is no confusion on the part of the drivers where they are to travel. Cones are usually used on non-freeways, or for short operations on freeways. Flexible drums are preferred for highway work zones and are required for night-time operations on highways.
Barricades are used to temporary close or block off a portion of a road. They may be easily tipped over by wind and motorists if they are not well secured firmly in the position (usually by sand bags). A better option for traffic guidance is a channeling device or continuous barrier (see protection below).
Protection - The protection of the workplace can be ensured by the use of physical barriers such as concrete barriers, crash trucks, and crash cushions.
For example, continuous physical barriers are made from concrete or deformable elements filled with ballast and reinforced by a steel bars. Concrete barriers must not be placed at an angle or perpendicular to the direction of traffic.
Figure 2: Interconnecting channelizing device
Buffer vehicles are used to protect workers during short duration or mobile work. Some buffer vehicles can be equipped with attenuators that reduce the force of the impact in case of crash. These types of buffer trucks are also known as crash trucks.
Figure 3: Vehicle-mounted crash attenuator
Temporary crash cushions absorb the energy of collision, have the advantage of being easily restored, and can be used in temporary situations where quick set up and removal the work zone is needed.
The personal protection equipment must be adequate for the job. In general, road workers should wear a hard hat with high visibility colour strip, CSA-certified safety boots, and highly visible vest or clothing. In general, wear high visibility clothing that complies with the CSA Standard Z96-15 High-Visibility Safety Apparel Consult the CSA Standard or check with your provincial legislation for specific requirements.
NOTE: Images in this document are from: British Columbia Ministry of Transportation and Infrastructure: “Traffic Management Manual for Work on Roadways, 2015 Office Edition, Interim”