| City of Knoxville
Traffic Engineering Division
Traffic Signal Installations
The City of Knoxville installs a traffic signal as part of the
regular signal index program.
A developer installs a traffic signal in conjunction with a new
development that justifies a signal (as approved by MPC and by Traffic
A traffic signal is installed as part of a roadway improvement
project by TDOT or the City of Knoxville.
Traffic signals are installed within the City of Knoxville by one
of three ways:
The City signal index program takes place in late January each year.
A list of candidate locations for new signals are compiled throughout
the previous year. Accident and traffic volume information is gathered
for each candidate location. This ranked list is discussed among the
Traffic Division engineers, and the most practical solutions for a
signal are selected from the top of the list.
More specifically, the volume criteria for signal installations are
described in warrants published by the Federal Highway Administration
(FHWA). These criteria, also described in the Manual on Uniform Traffic
Control Devices (MUTCD), call for a certain volume of traffic on the
main street and the side street. Accident statistics are also important,
because if a location has a high number of accidents preventable by
a traffic signal (such as right-angle collisions), it will be higher
on the index.
Traffic Signal Operations
Traffic signals operations involve timing, phasing and coordination.
Signals are retimed and phases are added whenever justified by engineering
studies. Traffic counts are usually involved in any retiming or rephasing.
Signal timing is based on a logic of providing as much time as possible
to the major street, thus serving the larger motoring public interest.
This also aids in the coordination of traffic signals.
Signal phasing is where different traffic movements are given exclusive
right-of-way by a distinct signal display. Signal phases are added
as justified by engineering study, based upon traffic volumes of turning
and opposing traffic. The tradeoff with added phases is that by adding
a phase, time is taken away from the other movements at the intersection,
increasing delays and traffic backups.
Signal coordination is set with Knoxville's Closed Loop Signal System,
which utilizes timing developed from computer traffic models, adjusted
by field observation. This system is broken up into eighteen subsystems
for the following major routes:
North Broadway from Foley to Adair
North Broadway I-640 system from I-640W exit to Powers
North Broadway from Raleigh/Walker to Grainger
North Broadway from Glenwood to Jackson
Henley & Western from Henley/Main to Western/Dale
Chapman Highway from Blount to Fronda
Cumberland Street from Walnut to Neyland
Kingston Pike from Scenic to Keener
Kingston Pike from Papermill to Downtown West (also includes West
Towne Mall signals on Morrell and Montvue, as well as Ray Mears
at Downtown West)
Kingston Pike from Gallaher View to Fort Sanders West Blvd (also
includes Cedar Bluff from N Peters to Executive Park, and signals
for the I-40/Walker Springs interchanges)
Middlebrook Pike from Vanosdale to Gallaher View (also includes
Walker Springs at Gallaher View)
Western Avenue from Shoppers Lane to Texas Avenue
Clinton Highway from Tillery to Merchants (also includes Merchants
from Schubert to the Ingles store)
Emory Road from I-75S exit to the Ingles store
Knoxville Center shopping mall (includes signals on Millertown
Pike and Washington Pike)
Schaad Road / Callahan Road / Clinton Highway
17th Street from Western Avenue to Highland Street
Lovell Road at I-40 / Lovell Road at Parkside Drive / westward
to Baptist Hospital entrance and Herons Nest Road