Traffic signals don't always prevent crashes. In many instances, the total number of crashes and injuries increase after they're installed.
Where signals are used unnecessarily, the most common results are a reduction in right-angle collisions but an increase in total crashes, especially the rear-end type collision. In addition, pedestrians are often lulled into a false sense of security.
In deciding whether a traffic signal will benefit a particular location the following criteria will be evaluated:
• Does the number of vehicles on intersecting streets create confusion or congestion?
• Is main street traffic so heavy that drivers on the side street will try to cross unsafely?
• Are there enough pedestrians trying to cross a busy main street to create a hazard?
• Does the number of school children crossing a street require special controls for their protection?
• Will a signal allow for continuous, uniform traffic flow with a minimum number of vehicle stops?
• Does an intersection's crash history indicate that a signal will reduce the possibility of a collision?
Our staff will compare the existing conditions against nationally accepted minimum standards established by The Manual on Uniform Traffic Control Devices (MUTCD) - Section 4C. At intersections where standards have been met, the signals generally operate effectively with good public compliance. Where not met, compliance is generally reduced resulting in additional hazards.
While a properly placed traffic signal improves the flow and decreases crashes, an unnecessary one can be a source of danger and annoyance to all who use an intersection: pedestrians, cyclists and drivers.
The Manual on Uniform Traffic Control Devices