When setting up a traffic control plan, or TCP, it should be laid out in a set of specific plan sheets, with standard indexes and/or plan notes describing how traffic will be controlled during construction. How detailed the plan is depends on the project’s complexity, with an overall goal of a clear and concise TCP.
Continuing on with the various aspects of a TCP, next up in our discussion is tje temporary traffic control zone. These include the entire section of roadway under construction, from the first warning sign to the last traffic control device, where traffic is returned to its normal flow. These zones are generally divided into four areas. In the order drivers encounter them, they are:
- Advanced warning area
- Transition area
- Activity area
- Termination area
Let’s walk through each of these areas (figuratively speaking, of course), and review what each one’s purpose is.
- Advanced Warning Area – Road users warned of upcoming work zone/incident area
In the advance warning area, drivers are told what to expect. The warning may be a single sign, flashing lights on a vehicle, or a series of signs in advance of the traffic control zone transition area. Spacing of these warnings depends on what type of work area is being done, such as freeways as compared to city streets. The two main types of construction classifications are Urban or Rural. Advance warning may not needed when the activity area is sufficiently removed from the driver’s path that it does not interfere with traffic.
- Transition Area – Road users redirected out of normal traffic path
When traffic needs to be redirected, it must be channeled from its normal path to a new path. This redirection is intended to occur at the beginning of the transition area. In mobile operations, this transition area moves with the work space.
- Activity Area – Section of highway where work activity takes place
The activity area is an area of roadway where the work takes place. It’s made up of the work space and the traffic space, and may have one or more buffer spaces. It’s closed to traffic and set aside for workers, equipment, and material. Work space may be fixed or may move as work progresses. Sometimes, it may have space for stored emergency vehicles such as tow trucks so they can respond quickly to traffic incidents.
- Termination Area – Where road users return to normal traffic path
Finally, the termination area returns traffic to its normal traffic path. The termination area extends from the downstream end of the work area to End Road Work signs, though it’s important to note that using End Road Work signs may not be helpful. One example is if there are additional traffic control zones coming up within a mile of the end of the work space in rural areas, or about a quarter-mile within urban areas.
In my next post, I’ll focus in on tapers, which are used in both the transition and termination areas of the traffic control zone.