The components of a traffic control zone are the advance warning area, buffer space, work space, and the taper. Each of these components is important and should be considered when preparing to plan a new traffic control zone. A traffic control zone can help reduce the risk of accidents on the highway. It will also improve the overall flow of traffic.

Work space

The work space is the section of a highway that is used for work and maintenance activities. Workspaces are typically delineated by temporary barriers and signs. Depending on the scope of the project, the layout of the work area may change. In such situations, the layout of the work zone should be modified according to sound engineering judgment.

Work spaces are normally separated by a temporary barrier, such as a flagger, or a traffic island. Road users are then routed through the work space and then out again. If an intersection is involved, special considerations might be needed.

Traffic control devices are placed in a work zone based on sight obstructions, roadway characteristics, and the work zone configuration. Some of these devices may be installed in advance of a work space and others after it.

Advance warning devices are required for work zones. They may be a single sign, a series of lead-in signs, or high-intensity rotating lights. Each device should be placed where it will provide adequate visibility for road users. Alternatively, a shadow vehicle could be placed in the closed lane in advance of the work area.

The traffic control plan is developed in conjunction with the district maintenance personnel. The traffic volume and duration of the work area are major factors in determining the type of traffic control used. Flaggers should be stationed at each end of the work area where they can effectively manage traffic.

The length of the work zone is determined by a combination of the highway design speed, the location of the work, and the anticipated duration of the activity. It can be several miles or several kilometers.

Advance warning area

The Advance warning area of a traffic control zone is the area where road users are notified of activities and events that are upcoming. This can include a series of signs or high-intensity rotating lights. These can be placed in the roadway, or placed on portable supports or trailers.

One of the most important reasons to place advance warning signs is to prepare the approaching traffic. Providing this warning can prevent a traffic incident. Ideally, the warning should be provided in a way that will enable motorists to adjust their driving pattern. A sign with a short message may suffice.

There are many factors that influence the type of advance warning that is used. Road conditions, weather, and visibility all play a part. Some agencies use a combination of advance warning and signal control. Others dispatch additional blocking vehicles.

The advance warning area of a TTC zone should be well-signed and well-placed. An example of a good warning sign is the ROAD WORK (WO20-1) sign. It should be the first sign that the road user sees.

Depending on the speed of the traffic and the roadway conditions, the distances between warning signs should vary. However, there are a few general rules of thumb. Generally, signs should be placed with respect to the speed limit. On higher-speed roadways, multiple signs can be placed, while low-speed residential streets generally have one sign.

If a single sign is placed on a roadway, it should be at least four feet above the ground surface. It should also be visible to approaching vehicles. Often, additional flags or warning lights are added to improve visibility.

Signage is an integral part of temporary traffic control. Signs must be large enough to be seen, but standardized so that the signs are easily understood by drivers.

Buffer space

Buffer space is an important part of the roadway and a must have for traffic control. It can improve motorist safety by offering additional space for errant drivers and by giving warning to oncoming traffic. These buffer zones may be located longitudinally or laterally on the road. Aside from providing a place for motorists to stop, they may also be used to separate traffic from workers and excavations.

The best way to create a buffer space is to use channelizing devices such as cones and markers. An alternative method is to use temporary barriers such as humps. This will prevent pedestrians from entering the zone. In addition, the width of the buffer space should be determined by engineering judgment.

There are several other factors to consider in determining the best buffer space for a specific location. These include the amount of work to be done in the area, the distance and time of year, and the potential effects on traffic volume and speed. Fortunately, research shows that the relationship between traffic and work zones is not a one-to-one affair.

To get the most out of your buffer space, it’s important to understand its purpose. This will enable you to design a buffer that meets your needs. You should also know what it isn’t. For example, a buffer zone should be free of steep slopes and other obstacles that would inhibit a motorist’s ability to make a quick stop.

Buffer spaces should be clearly marked with traffic signs and cones to ensure that drivers are able to find their way around the zone. Although the best buffer space can’t make a location safe, it can improve motorist safety and minimize the chance of heavy equipment hitting a passing vehicle.

Signs used for temporary traffic control

Temporary traffic control signs are used to notify drivers and road users of changes to roadway conditions and other events. They must be visible and easily understood by motorists. In addition, they must be placed at high enough elevations so they can be seen. Using incorrect signage can lead to frustration and confusion for motorists.

Temporary traffic control signals are sometimes preferred over other types of temporary markings, but signs should be used when signals are not available. Portable changeable message signs can also be used as temporary TTC devices. These signs provide information to drivers on the condition of the roadway and can be used to augment conventional traffic signs. Unlike portable signs, these conventional devices must be mounted on the right side of the roadway.

Portable changeable message signs must be placed at a distance in advance of the event. This allows time for lane changes and speed adjustments to be made. For this reason, they should not be used as substitutes for conventional pavement markings. If the event occurs during nighttime hours, portable signs must have a flashing warning light.

The symbols and legends on portable changeable message signs must be enlarged to account for the oversized size. The uppercase letters must be seven inches in height. Similarly, the lowercase lettering must be at least six inches in height. When signs are mounted on supports, they must be sized to accommodate the minimum 150 square inches of orange high intensity retroreflective sheeting.

Other forms of temporary markings include edge lines and channelizing devices. Depending on the design speed of the curves, a double reverse turn sign or a double reverse curve sign may be necessary.

Supported by a traffic taper

A traffic taper is a piece of equipment that is used to redirect traffic to a new route. This is usually done in conjunction with pavement markings and other channelizing devices. While this may not be the best way to control traffic, it can be an important safety measure.

The most important part of the taper is its placement. Traffic control personnel must know the proper locations for the requisite equipment. For instance, the lane that is being closed must be in the right place. Likewise, a contractor must coordinate the pickup of the closure. Once the work is finished, the taper can be removed.

The most effective tapers are those that provide the most benefits to the most road users. While there is no standard size for these types of devices, a minimum of five at a 20-foot spacing is a good bet. Depending on the lane width and traffic conditions, more can be added.

A taper is also an excellent signaling device. One lane is closed in each direction, allowing the remaining lanes to remain open. An example of a one-lane, two-way taper can be seen in Figure 6C-3. These types of taper are typically used to redirect one lane of a two-lane undivided highway.

Other examples include a supplemental taper, a longitudinal buffer space between the work zone and the downstream taper, and an advance warning sign. All of these are useful to the right traffic planner. Whether you are constructing or maintaining a highway, having the right traffic control apparatus can be a determining factor in the safe and timely completion of your project.

While a taper is the most exciting component of any traffic control system, there are a number of other factors that should be considered. It is best to consult the Manual for Uniform Traffic Control Devices (OUTCD) for more information.