The Fundamentals for Smooth Traffic Control

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It’s tempting to get angry when stuck in traffic but when it comes to traffic control, impatience will have to do. Drivers often fail to realize just how difficult and necessary traffic control is in day-to-day operations. Without effective, well-planned traffic control, drivers would certainly have much more to complain about during their daily commutes!

Orange cones, traffic signs, and flares aren’t uncommon on the roads but many motorists are unaware of just how strategic their use is. It begs the question: What is traffic control? The New York State Department of Transportation (NYSDT) defines it as efforts that make “traffic safety and temporary traffic control an integral and high-priority element of every project from planning through design, construction, and maintenance.”


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NYSDT lays out a series of points regarding traffic control. Traffic control projects:

  • “Inhibit traffic movement as little as possible.”
  • “Provide clear and positive guidance to drivers and pedestrians as they approach and travel through the temporary traffic control zone.”
  • “Inspect traffic control elements routinely and modify when necessary.”
  • “Pay increased attention to roadside safety near temporary traffic control.”
  • “Train all persons that select, place and maintain temporary traffic control devices.”

The most important aspect of traffic control projects is known as the “work zone.” The work zone is the area of road between the first sign that indicates roadwork and the point in which traffic is no longer affected. Specifically, every work zone is divided into four sections:

1. Advanced Warning Area: The area informs incoming vehicles that roadwork is ahead.

2. Transition Area: The area that moves vehicles into a designated area away from the roadwork.

3. Activity Area: The area in which the actual roadwork is being done.

4. Termination Area: The area beyond the roadwork in which normal traffic resumes.

The four-section layout ensures the safety of the workers and the motorists. It also gives roadwork crews ample space to complete the project.

Each area has its own guidelines for separating traffic:

Advanced Warning Area

In the advanced warning area, for example, the actual tapering of traffic doesn’t begin until vehicles enter well into the zone. Typically, at least three warning signs are placed in the zone before vehicles have to alter traffic. The “shoulder taper” begins the restriction of traffic. That is when traffic cones and other signs are placed in order to direct traffic to the left or right lane. As the name suggests, the equipment is placed in the shoulder of the road, not the road itself.

Transition Area

The shoulder taper leads directly into the transition area. The shoulder taper transforms into the “merging taper” in that the traffic cones and signs are placed directly on the left or right lane. Typically, the merging taper is about three times the length of the shoulder taper, giving plenty of space for the motorists to make the transition.

Activity Area

It is when the motorists enter the activity area that the layout gets a bit tricky. The activity area begins when the traffic is fully restricted. For example, if the traffic is funneled from two lanes into one lane, the activity area begins where the single lane is fully established. The activity area is split into three buffer zones:

1. Buffer Space (Longitudinal): This is the first zone of the activity area. As the name suggests, it provides space between the workers, the motorists, and the work area itself. No vehicles, workers, or equipment are allowed in this area.

2. Roll Ahead Space: This is the second zone of the activity area. It is situated between the buffer space and the work space. It provides the last area of protection for the work space.

3. Work Space: The final zone of the activity area, the work space is where the actual road work is being done. The equipment, workers, and materials needed for the project are found here. In a way, every component of the work zone leads up to the work space.

Termination Area

Once motorists pass the workspace, normal traffic resumes and they can get on their merry way. The first area of the termination area is known as the “downstream taper.” This is where the traffic gradually returns to normal. After the downstream taper, there is a sign that indicates that the road-work is complete and motorists can resume their normal driving by using all of the road’s lanes.

There are two other terms to keep in mind regarding work zones. The “traffic space” is where the actual traffic is directed, i.e. between the traffic cones and the shoulder. For conventional roadways, it is at least 10 feet. For expressways and freeways, it is at least 11 feet. There is also the “buffer space” (lateral). Not to be confused with the buffer space (longitudinal) in the activity area, this buffer space is the area in between the traffic space and the workspace. It is provided in order to provide an extra layer of protection for the roadwork crews and their equipment.

Of course, each road and workspace is different. Depending on the conditions and characteristics of the road and the workspace, the size of these components, such as the buffer space and merging taper, change. The types of equipment and signs used also heavily depend on the individual project. Regardless, proper traffic control is key when repairing and improving the roads millions of motorists across the country depend on everyday.