The City of Santa Clarita receives many requests and inquiries each month concerning the operation and installation of traffic signals throughout the City.
WHY ARE TRAFFIC SIGNALS NEEDED?
As traffic volumes increase beyond the capability of lesser controls, such as a four-way stop sign, it may become necessary to install a traffic signal. State and federal guidelines require that intersections meet certain criteria called "warrants" before installing a traffic signal. These guidelines compare existing conditions against national standards. Several types of warrants can be used for the evaluation process. A review includes:
- The amount of vehicular and pedestrian traffic flow.
- The need to provide interruption to the major flow for side street vehicles and pedestrians.
- Special conditions, such as hills and curves.
- The accident history at the intersection.
- The proximity of schools.
ADVANTAGES OF TRAFFIC SIGNALS
While all intersections must satisfy warrants to qualify for a signal, all locations meeting signal warrants will not necessarily be signalized. Delay, congestion, driver confusion, or other evidence of the need for right-of-way assignment must be shown. Signal installations are also subject to availability of funds for construction. Sometimes traffic signals are installed as part of a private development to mitigate traffic impacts. Their location must also meet the appropriate "warrants" discussed above.
Traffic signals are valuable devices for the control of vehicle and pedestrian traffic. However, because they assign the right-of-way to various traffic movements, traffic signals exert a substantial influence on traffic flow. Warranted traffic signals that are properly located and operated usually have one or more of the following advantages:
- They can provide for orderly movement of traffic.
- Where proper physical layouts and control are used, they can increase the traffic-handling capacity of the intersection.
- They can reduce the frequency of certain types of accidents, especially right-angle collisions.
- Under favorable conditions, they can be coordinated to provide for continuous or nearly continuous movement of traffic at a specific speed along a given route.
- They can be used to interrupt heavy traffic to permit other traffic, vehicular or pedestrian, to cross.
DISADVANTAGES OF TRAFFIC SIGNALS
Many people believe that traffic signals provide the solution to all traffic problems at intersections. However, traffic signal installations, even though warranted by traffic and roadway conditions, can be ill designed, ineffectively placed, improperly operated, or poorly maintained The following factors can result from improper or unwarranted signal installations:
- Excessive traffic delay may result.
- Motorists may be more likely to disobey the signal indication.
- Motorists may use less adequate routes, such as residential streets, in an attempt to avoid such signals.
- Accident frequency, such as rear-end collisions, can be significantly increased at unwarranted signals or at locations where installation was not based on sound engineering analysis.
WHAT IS THE PROCESS FOR SIGNALIZING AN INTERSECTION
Several steps need to be followed before a traffic signal meets legal requirements for installation. This process takes at least six to nine months to complete.
TRAFFIC SIGNAL PRIORITY RATING SYSTEM
In addition to signal warrants, in 1995 the City established the "Signal Priority Rating System." Warranted locations are assigned points and ranked with all other candidate locations in the City. The system was established to better allocate limited funds by selecting only the top-ranked candidate locations for signal installation. Due to the City's growth and new roadways, demand for more traffic signals has increased. Typically, the City has the budget for one traffic signal per year.
SIGNAL PRIORITY SCHEDULE
All traffic signal evaluations are performed once a year, typically in the spring of each year. Locations studied may include previous years' warranted but unfunded locations, new requests, and other locations recommended by the Traffic Engineering Division. Warranted locations are placed into the Priority Rating System. The results are then submitted to the City Council for approval. Letters advising of the proposed ranking are then sent to requesters prior to the scheduled City Council meeting.
DESIGN AND CONSTRUCTION
Once a location is selected for signalization, the traffic signal plan is prepared and sent out to bid before the signal is constructed. This process normally takes 12 to 18 months to complete.
IF YOU HAVE ANY QUESTIONS, REQUESTS, OR SUGGESTIONS CONCERNING TRAFFIC SAFETY MATTERS, PLEASE CONTACT THE TRAFFIC ENGINEERING DIVISION AT (661) 255-4942