6B. Fundamental Principles
All traffic control devices used on street and highway construction, maintenance, utility, or incident management (temporary traffic control) operations shall conform to the applicable specifications of this manual.
Special plan preparation and coordination with transit and other highway agencies, police and other emergency units, utilities, schools, railroads, etc. may be needed to reduce unexpected and unusual traffic operation situations.
During temporary traffic control activities, commercial vehicles may need to follow a different route from automobiles because of bridge, weight, clearance, or geometric restrictions. Also, vehicles carrying hazardous materials may need to follow a different route from other vehicles. Truck Route National Network and hazardous cargo signs are included in section 2B-43.
Principles and procedures, which experience has shown tend to enhance the safety of motorists and workers in the vicinity of temporary traffic control areas, are included in the following listing. These principles and procedures provide a guiding philosophy of good temporary traffic control used in zone traffic control for the practitioner. They do not establish specific standards and warrants (individually addressed in the succeeding sections of this part).
- Traffic safety in temporary traffic control areas should be an integral and high-priority element of every project from planning through design and construction. Similarly, maintenance and utility work should be planned and conducted with the safety of motorists, pedestrians, and workers kept in mind at all times. Formulating specific plans for incident management traffic control is difficult because of the variety of situations that can arise. Nevertheless, plans should be developed in sufficient detail to provide safety for motorists, pedestrians, workers, and enforcement/emergency personnel and equipment.
- The basic safety principles governing the design of permanent roadways and roadsides should also govern the design of temporary traffic control zones. The goal should be to route traffic through such areas using geometrics and traffic control devices comparable to those for normal highway situations.
- A traffic control plan, in detail appropriate to the complexity of the work project or incident, should be prepared and understood by all responsible parties before the site is occupied. Any changes in the traffic control plan should be approved by an official trained in safe traffic control practices.
- Traffic movement should be inhibited as little as practicable.
- Traffic control in work and incident sites should be designed on the assumption that drivers will reduce their speeds only if they clearly perceive a need to do so. Reduced speed zoning should be avoided as much as practical.
- Frequent and abrupt changes in geometrics-such as lane narrowing, dropped lanes, or main roadway transitions requiring rapid maneuvers-should be avoided.
- Provisions should be made for the safe operation of work or incident management vehicles, particularly on high-speed, high- volume roadways.
- Roadway occupancy and work completion time should be minimized to reduce exposure to potential hazards.
- Pedestrians should be provided with access and safe passage through the temporary traffic control zone at all times.
- Roadway occupancy should be scheduled during off-peak hours and, if necessary, night work should be considered.
- Drivers and pedestrians should be guided in a clear and positive manner while approaching and traversing the temporary traffic control zone.
- Adequate warning, delineation, and channelization by means of proper pavement marking, signs, or use of other devices that are effective under varying conditions of light and weather should be provided where appropriate to assure the driver and pedestrian of positive guidance before approaching and while passing through the work area.
- Signs, pavement markings, channelizing devices, delineators, and other traffic control devices that are inconsistent with intended travel paths through long-term work spaces should be removed. In short-duration and mobile work spaces where retained permanent devices are inconsistent with intended travel paths, attention should be given to devices that highlight or emphasize the appropriate path.
- Flagging procedures, when used, can provide positive guidance to drivers traversing the temporary traffic control area. Flagging should be employed only when all other methods of traffic control are inadequate to warn and direct drivers.
- To ensure acceptable levels of operation, routine inspection of traffic control elements should be performed.
- Individuals who are trained in the principles of safe traffic control should be assigned responsibility for safety at work sites. The most important duty of these individuals is to ensure that all traffic control measures implemented on the project are necessary, conform to the traffic control plan, and are effective in providing safe conditions for motorists, pedestrians, and workers.
- Modification of traffic controls or working conditions may be required to expedite safe traffic movement and to promote worker safety. It is essential that the individual responsible for safety have the authority to control the progress of work on the project with respect to obtaining safe conditions, including the authority to modify conditions or halt work until applicable or remedial safety measures are taken.
- Temporary traffic control areas should be carefully monitored under varying conditions of traffic volume, light, and weather to ensure that traffic control measures are operating effectively and that all devices used are clearly visible, clean, and in good repair.
- When warranted, an engineering analysis should be made (in cooperation with law enforcement officials) of all accidents occurring in temporary traffic control zones. Temporary traffic control zones and accident records should be monitored to identify and analyze traffic accidents or conflicts. For example, skid marks or damaged traffic control devices may indicate the need for changes in the traffic control.
- All traffic control devices should be removed when no longer needed. When work is suspended for short periods, advance warning signs that are no longer appropriate shall be removed, covered, or turned, and other inappropriate devices removed from the work area so they are not visible to drivers.
- The maintenance of roadside safety requires attention during the life of the temporary traffic control zone because of the potential increase in hazards.
- To accommodate run-off-the-road incidents, disabled vehicles, or emergency situations, it is desirable to provide an unencumbered roadside recovery area.
- Channelization of traffic should be accomplished by pavement markings, signs, and/or lightweight channelizing devices that will yield when hit by errant vehicles.
- Whenever practical, equipment, workers, private vehicles, materials, and debris should be stored in such a manner as not to be vulnerable to run-off-the-road vehicle impact.
- Pedestrian paths through the temporary traffic control zone should be protected to minimize pedestrian exposure to errant vehicles.
- Each person whose actions affect temporary traffic control zone safety-from upper-level management personnel through field personnel-should receive training appropriate to the job decisions each is required to make. Only those who are trained in safe traffic control practices, and who have a basic understanding of the principles established applicable standards and regulations (including those of the MUTCD), should supervise the selection, placement, and maintenance of traffic control devices in work and incident management areas.
- The control of traffic through work areas is an essential part of street and roadway construction, utility and maintenance operations. For these operations there must be adequate legislative authority for the implementation and enforcement of needed traffic regulations, parking controls, speed zoning, and incident management. Such statutes must provide sufficient flexibility in the application of traffic control to meet the needs of changing conditions in work areas.
- Maintaining good public relations is necessary. The cooperation of the various news media in publicizing the existence of and reasons for work sites can be of great assistance in keeping the motoring public well informed.