Temporary Traffic Control Zone (TTCZ) – area of a highway where road user conditions are changed because of a work zone or incident by the use of temporary traffic control devices, flaggers, uniformed law enforcement officers, or other authorized personnel.
Functions of a Temporary Traffic Control
No one set of TTC devices can satisfy all conditions for a given project or incident. At the same time, defining details that would be adequate to cover all applications is not practical. The TTC selected for each situation depends on the following:
Roadwork Traffic Management Guide:
Components of a Temporary Traffic Control Zone
Definition of Terms
Situation 1 (Common)
Advance warning sign must be located at a minimum distance of 2D meters before the start of the works, or if there is a transition area, the start of the taper.
For example, if the approach speed of traffic is 60 kph then the ‘ROADWORKS AHEAD’ sign should be a minimum of 120 meters before the taper or works area.
In cases where a specific action is required from road users or drivers, additional signs may be provided in the advance warning area. The sign closest to the work should be at a distance of 2D with other signs generally spaced D meters apart.
If two or more signs are provided in the advance warning area, the ‘ROADWORKS AHEAD’ sign may need to be a distance of 3D or more prior to the works. However, where visibility is good and there are more than two advanced signs, the spacing of signs may be reduced to a minimum of 0.5D.
The way that you have chosen to manage the traffic at then worksite, will determine you the type of taper you should use
Lateral Shift Taper shifts a line of traffic sideways when it does not need to merge with another line of traffic traveling in the same direction sometimes referred to as a “diverge taper”. Should be at least “D” meters long.
For example if the approach speed of traffic is 50 kph the lateral shift taper should be 50 meters. However, when a Traffic Controller is being used a 30 meter taper is adopted as the traffic would be approaching the taper at a slower speed.
Merge Taper shifts a line of traffic sideways where the traffic must join with another line of traffic traveling in the same direction; should be at least 2D meters long.
For example, if traffic is traveling at a speed of 70 kph the merge taper should be 140 meters. A merge taper requires a longer distance because drivers are required to merge into common road space.
Devices used for forming the taper may be:
The spacing for Traffic Cones or Bollards to create a taper should be 5 to 10 meters.