Chapter 6I. Control of Traffic Through Traffic Incident Management Areas
Section 6I.01 General
Support:
Whenever the acronym "TTC" is used in this Chapter, it
refers to "temporary traffic control".
Standard:
The needs and control of all road users (motorists, bicyclists,
and pedestrians within the highway, including persons with disabilities
in accordance with the Americans with Disabilities Act of 1990 (ADA),
Title II, Paragraph 35.130) through a TTC zone shall be an essential
part of highway construction, utility work, maintenance operations,
and the management of traffic incidents.
Support:
A traffic incident is an emergency road user occurrence, a natural
disaster, or other unplanned event that affects or impedes the normal
flow of traffic.
A traffic incident management area is an area of a highway where temporary traffic controls are imposed by authorized officials in response to a road user incident, natural disaster, hazardous material spill, or other unplanned incident. It is a type of TTC zone and extends from the first warning device (such as a sign, light, or cone) to the last TTC device or to a point where vehicles return to the original lane alignment and are clear of the incident.
Traffic incidents can be divided into three general classes of duration, each of which has unique traffic control characteristics and needs. These classes are:
- Major—expected duration of more than 2 hours;
- Intermediate—expected duration of 30 minutes to 2 hours; and
- Minor—expected duration under 30 minutes.
The primary functions of TTC at a traffic incident management area are to move road users reasonably safely and expeditiously past or around the traffic incident, to reduce the likelihood of secondary traffic crashes, and to preclude unnecessary use of the surrounding local road system. Examples include a stalled vehicle blocking a lane, a traffic crash blocking the traveled way, a hazardous material spill along a highway, and natural disasters such as floods and severe storm damage.
Guidance:
In order to reduce response time for traffic incidents, highway
agencies, appropriate public safety agencies (law enforcement, fire
and rescue, emergency communications, emergency medical, and other
emergency management), and private sector responders (towing and
recovery and hazardous materials contractors) should mutually plan
for occurrences of traffic incidents along the major and heavily
traveled highway and street system.
On-scene responders should be trained in safe practices for accomplishing their tasks in and near traffic. Responders should always be aware of their visibility to oncoming traffic and take measures to move the traffic incident as far off the traveled roadway as possible or to provide for appropriate warning.
Responders arriving at a traffic incident should, within 15 minutes of arrival on-scene, estimate the magnitude of the traffic incident, the expected time duration of the traffic incident, and the expected vehicle queue length, and then should set up the appropriate temporary traffic controls for these estimates.
Option:
Warning and guide signs used for TTC traffic incident management
situations may have a black legend and border on a fluorescent pink
background (see Figure 6I-1).
Figure 6I-1 Examples of Traffic Incident Management Area Signs
Support:
While some traffic incidents might be anticipated and planned for,
emergencies and disasters might pose more severe and unpredictable
problems. The ability to quickly install proper temporary traffic
controls might greatly reduce the effects of an incident, such as
secondary crashes or excessive traffic delays. An essential part
of fire, rescue, spill clean-up, highway agency, and enforcement
activities is the proper control of road users through the traffic
incident management area in order to protect responders, victims,
and other personnel at the site while providing reasonably safe
traffic flow. These operations might need corroborating legislative
authority for the implementation and enforcement of appropriate
road user regulations, parking controls, and speed zoning. It is
desirable for these statutes to provide sufficient flexibility in
the authority for, and implementation of, TTC to respond to the
needs of changing conditions found in traffic incident management
areas.
Option:
For traffic incidents, particularly those of an emergency nature,
TTC devices on hand may be used for the initial response as long
as they do not themselves create unnecessary additional hazards.
Section 6I.02 Major Traffic Incidents
Support:
Major traffic incidents are typically traffic incidents involving
hazardous materials, fatal traffic crashes involving numerous vehicles,
and other natural or man-made disasters. These traffic incidents
typically involve closing all or part of a roadway facility for
a period exceeding 2 hours.
Guidance:
If the traffic incident is anticipated to last more than 24 hours,
applicable procedures and devices set forth in other Chapters of
Part 6 should be used.
Support:
A road closure can be caused by a traffic incident such as a road
user crash that blocks the traveled way. Road users are usually
diverted through lane shifts or detoured around the traffic incident
and back to the original roadway. A combination of traffic engineering
and enforcement preparations is needed to determine the detour route,
and to install, maintain or operate, and then to remove the necessary
traffic control devices when the detour is terminated. Large trucks
are a significant concern in such a detour, especially when detouring
them from a controlled-access roadway onto local or arterial streets.
During traffic incidents, large trucks might need to follow a route separate from that of automobiles because of bridge, weight, clearance, or geometric restrictions. Also, vehicles carrying hazardous material might need to follow a different route from other vehicles.
Some traffic incidents such as hazardous material spills might require closure of an entire highway. Through road users must have adequate guidance around the traffic incident. Maintaining good public relations is desirable. The cooperation of the news media in publicizing the existence of, and reasons for, traffic incident management areas and their TTC can be of great assistance in keeping road users and the general public well informed.
The establishment, maintenance, and prompt removal of lane diversions can be effectively managed by inter-agency planning that includes representatives of highway and public safety agencies.
Guidance:
All traffic control devices needed to set up the TTC at a traffic
incident should be available so that they can be readily deployed
for all major traffic incidents. The TTC should include the proper
traffic diversions, tapered lane closures, and upstream warning
devices to alert approaching traffic of the end of a queue.
Attention should be paid to the end of the traffic queue such that warning is given to road users approaching the end of the queue.
If manual traffic control is needed, it should be provided by qualified flaggers or uniformed law enforcement officers.
Option:
If flaggers are used to provide traffic control for an incident
management situation, the flaggers may use appropriate traffic control
devices that are readily available or that can be brought to the
traffic incident scene on short notice.
Guidance:
When flares are used to initiate TTC at traffic incidents, more
permanent traffic control devices should replace them as soon as
practical. Both the flare and its supporting device should then
be removed from the roadway.
Guidance:
On-scene responders should be trained in safe practices for accomplishing
their tasks in and near traffic. Responders should always be aware
of their visibility to oncoming traffic and take measures to move
the traffic incident as far off the traveled roadway as possible
or to provide for appropriate warning.
Section 6I.03 Intermediate Traffic Incidents
Support:
Intermediate traffic incidents typically affect travel lanes for
a time period of 30 minutes to 2 hours, and usually require traffic
control on the scene to divert road users past the blockage. Full
roadway closures might be needed for short periods during traffic
incident clearance to allow traffic incident responders to accomplish
their tasks.
The establishment, maintenance, and prompt removal of lane diversions can be effectively managed by inter-agency planning that includes representatives of highway and public safety agencies.
Guidance:
All traffic control devices needed to set up the TTC at a traffic
incident should be available so that they can be readily deployed
for intermediate traffic incidents. The TTC should include the proper
traffic diversions, tapered lane closures, and upstream warning
devices to alert approaching traffic of the end of a queue.
Attention should be paid to the end of the traffic queue such that warning is given to road users approaching the end of the queue.
If manual traffic control is needed, it should be provided by qualified flaggers or uniformed law enforcement officers.
Option:
If flaggers are used to provide traffic control for an incident
management situation, the flaggers may use appropriate traffic control
devices that are readily available or that can be brought to the
traffic incident scene on short notice.
Guidance:
When flares are used to initiate TTC at traffic incidents, more
permanent traffic devices should replace them as soon as practical.
Both the flare and its supporting device should then be removed
from the roadway.
On-scene responders should be trained in safe practices for accomplishing their tasks in and near traffic. Responders should always be aware of their visibility to oncoming traffic and take measures to move the traffic incident as far off the traveled roadway as possible or to provide for appropriate warning.
Section 6I.04 Minor Traffic Incidents
Support:
Minor traffic incidents are typically disabled vehicles and minor
crashes that result in lane closures of less that 30 minutes. On-scene
responders are typically law enforcement and towing companies, and
occasionally highway agency service patrol vehicles.
Diversion of traffic into other lanes is often not needed or is needed only briefly. It is not generally possible or practical to set up a lane closure with traffic control devices for a minor traffic incident. Traffic control is the responsibility of on-scene responders.
Guidance:
On-scene responders should be trained in safe practices for accomplishing
their tasks in and near traffic. Responders should always be aware
of their visibility to oncoming traffic and take measures to move
the traffic incident as far off the traveled roadway as possible
or to provide for appropriate warning.
When a minor traffic incident blocks a travel lane, it should be removed from that lane to the shoulder as quickly as possible.
Section 6I.05 Use of Emergency-Vehicle Lighting
Support:
The use of emergency-vehicle lighting (such as high-intensity rotating,
flashing, oscillating, or strobe lights) is essential, especially
in the initial stages of a traffic incident, for the safety of emergency
responders and persons involved in the traffic incident, as well
as road users approaching the traffic incident. Emergency-vehicle
lighting, however, provides warning only and provides no effective
traffic control. It is often confusing to road users, especially
at night. Road users approaching the traffic incident from the opposite
direction on a divided facility are often distracted by emergency-vehicle
lighting and slow their vehicles to look at the traffic incident
posing a hazard to themselves and others traveling in their direction.
The use of emergency-vehicle lighting can be reduced if good traffic control has been established at a traffic incident scene. This is especially true for major traffic incidents that might involve a number of emergency vehicles. If good traffic control is established through placement of advanced warning signs and traffic control devices to divert or detour traffic, then public safety agencies can perform their tasks on scene with minimal emergency-vehicle lighting.
Guidance:
Public safety agencies should examine their policies on the use
of emergency-vehicle lighting, especially after a traffic incident
scene is secured, with the intent of reducing the use of this lighting
as much as possible while not endangering those at the scene. Special
consideration should be given to reducing or extinguishing forward
facing emergency-vehicle lighting, especially on divided roadways,
to reduce distractions to oncoming road users.
Vehicle headlights not needed for illumination, or to provide notice to other road users of the incident response vehicle being in an unexpected location, should be turned off at night.