Current through Register Vol. 28, No. 3, September 1, 2024
01
Construction, maintenance, utility, and incident zones can all benefit from TTC
to compensate for the unexpected or unusual situations faced by road users.
When planning for TTC in these zones, it can be assumed that it is appropriate
for road users to exercise caution. Even though road users are assumed to be
using caution, special care is still needed in applying TTC
techniques.
02 Special plans
preparation and coordination with transit, other highway agencies, law
enforcement and other emergency units, utilities, schools, and railroad
companies might be needed to reduce unexpected and unusual road user operation
situations.
03 During TTC
activities, commercial vehicles might need to follow a different route from
passenger vehicles because of bridge, weight, clearance, or geometric
restrictions. Also, vehicles carrying hazardous materials might need to follow
a different route from other vehicles. The Hazardous Materials and National
Network signs are included in Sections 2B.62 and 2B.63, respectively.
04 Experience has shown that following the
fundamental principles of Part 6 will assist road users and help protect
workers in the vicinity of TTC zones.
Guidance:
05 Road user and worker safety and
accessibility in TTC zones 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
and accessibility of all motorists, bicyclists, pedestrians (including those
with disabilities), and workers being considered at all times. If the TTC zone
includes a grade crossing, early coordination with the railroad company or
light rail transit agency should take place.
Support:
06 Formulating specific plans for TTC at
traffic incidents is difficult because of the variety of situations that can
arise.
Guidance:
07 The following are the seven fundamental
principles of TTC:
1. General plans or
guidelines should be developed to provide safety for motorists, bicyclists,
pedestrians, workers, enforcement/emergency officials, and equipment, with the
following factors being considered:
A. The
basic safety principles governing the design of permanent roadways and
roadsides should also govern the design of TTC zones. The goal should be to
route road users through such zones using roadway geometrics, roadside
features, and TTC devices as nearly as possible comparable to those for normal
highway situations.
B. A TTC 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 TTC plan should be approved by an official who is
knowledgeable (for example, trained and/or certified) in proper TTC
practices.
2. Road user
movement should be inhibited as little as practical, based on the following
considerations:
A. TTC at work and incident
sites should be designed on the assumption that drivers will only reduce their
speeds if they clearly perceive a need to do so (see Section 6C.01).
B. Frequent and abrupt changes in geometrics
such as lane narrowing, dropped lanes, or main roadway transitions that require
rapid maneuvers, should be avoided.
C. Work should be scheduled in a manner that
minimizes the need for lane closures or alternate routes, while still getting
the work completed quickly and the lanes or roadway open to traffic as soon as
possible.
D. Attempts should be
made to reduce the volume of traffic using the roadway or freeway to match the
restricted capacity conditions. Road users should be encouraged to use
alternative routes. For high-volume roadways and freeways, the closure of
selected entrance ramps or other access points and the use of signed diversion
routes should be evaluated.
E.
Bicyclists and pedestrians, including those with disabilities, should be
provided with access and reasonably safe passage through the TTC
zone.
F. If work operations permit,
lane closures on high-volume streets and highways should be scheduled during
off-peak hours. Night work should be considered if the work can be accomplished
with a series of short-term operations.
G. Early coordination with officials having
jurisdiction over the affected cross streets and providing emergency services
should occur if significant impacts to roadway operations are
anticipated.
3.
Motorists, bicyclists, and pedestrians should be guided in a clear and positive
manner while approaching and traversing TTC zones and incident sites. The
following principles should be applied:
A.
Adequate warning, delineation, and channelization should be provided to assist
in guiding road users in advance of and through the TTC zone or incident site
by using proper pavement marking, signing, or other devices that are effective
under varying conditions. Providing information that is in usable formats by
pedestrians with visual disabilities should also be considered.
B. TTC devices inconsistent with intended
travel paths through TTC zones should be removed or covered. However, in
intermediate-term stationary, short-term, and mobile operations, where visible
permanent devices are inconsistent with intended travel paths, devices that
highlight or emphasize the appropriate path should be used. Providing traffic
control devices that are accessible to and usable by pedestrians with
disabilities should be considered.
C. Flagging procedures, when used, should
provide positive guidance to road users traversing the TTC
zone.
4. To provide
acceptable levels of operations, routine day and night inspections of TTC
elements should be performed as follows:
A.
Individuals who are knowledgeable (for example, trained and/or certified) in
the principles of proper TTC should be assigned responsibility for safety in
TTC zones. The most important duty of these individuals should be to check that
all TTC devices of the project are consistent with the TTC plan and are
effective for motorists, bicyclists, pedestrians, and workers.
B. As the work progresses, temporary traffic
controls and/or working conditions should be modified, if appropriate, in order
to provide mobility and positive guidance to the road user and to provide
worker safety. The individual responsible for TTC should have the authority to
halt work until applicable or remedial safety measures are taken.
C. TTC zones should be carefully monitored
under varying conditions of road user volumes, light, and weather to check that
applicable TTC devices are effective, clearly visible, clean, and in compliance
with the TTC plan.
D. When
warranted, an engineering study should be made (in cooperation with law
enforcement officials) of reported crashes occurring within the TTC zone. Crash
records in TTC zones should be monitored to identify the need for changes in
the TTC zone.
5.
Attention should be given to the maintenance of roadside safety during the life
of the TTC zone by applying the following principles:
A. To accommodate run-off-the-road incidents,
disabled vehicles, or emergency situations, unencumbered roadside recovery
areas or clear zones should be provided where practical.
B. Channelization of road users should be
accomplished by the use of pavement markings, signing, and crashworthy,
detectable channelizing devices.
C.
Work equipment, workers' private vehicles, materials, and debris should be
stored in such a manner to reduce the probability of being impacted by
run-off-the-road vehicles.
6. Each person whose actions affect TTC zone
safety, from the upper-level management through the field workers, should
receive training appropriate to the job decisions each individual is required
to make. Only those individuals who are trained in proper TTC practices and
have a basic understanding of the principles (established by applicable
standards and guidelines, including those of this Manual) should supervise the
selection, placement, and maintenance of TTC devices used for TTC zones and for
incident management.
7. Good public
relations should be maintained by applying the following principles:
A. The needs of all road users should be
assessed such that appropriate advance notice is given and clearly defined
alternative paths are provided.
B.
The cooperation of the various news media should be sought in publicizing the
existence of and reasons for TTC zones because news releases can assist in
keeping the road users well informed.
C. The needs of abutting property owners,
residents, and businesses should be assessed and appropriate accommodations
made.
D. The needs of emergency
service providers (law enforcement, fire, and medical) should be assessed and
appropriate coordination and accommodations made.
E. The needs of railroads and transit should
be assessed and appropriate coordination and accommodations made.
F. The needs of operators of commercial
vehicles such as buses and large trucks should be assessed and appropriate
accommodations made.
Standard:
08 Before any new detour or temporary route
is opened to traffic, all necessary signs shall be in place.
09 All TTC devices shall be removed as soon
as practical when they are no longer needed. When work is suspended for short
periods of time, TTC devices that are no longer appropriate shall be removed or
covered.
