2009 Edition Page 549
CHAPTER 6B. FUNDAMENTAL PRINCIPLES
Section 6B.01 Fundamental Principles of Temporary Trafc Control
Support:
01 Construction, maintenance, utility, and incident zones can all benet 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 specic plans for TTC at trafc incidents is difcult 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 ofcials, 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 ofcial who is knowledgeable (for example, trained and/or
certied) 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 trafc as soon
as possible.
D. Attempts should be made to reduce the volume of trafc 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 ofcials having jurisdiction over the affected cross streets and providing
emergency services should occur if signicant 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:
December 2009 Sect. 6B.01