| 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 be an asset and not a liability, traffic engineers
evaluate the following criteria:
- Does the number of vehicles on intersecting streets
create confusion or congestion?
- Is traffic on the main street so heavy that drivers
on the side street will try to cross when it is unsafe?
- Does the number of pedestrians trying to cross a busy
main street create confusion, congestion or hazardous
conditions?
- Does the number of school children crossing a street
require special controls for their protection? If so,
is a traffic signal the best solution?
- Will the installation of 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?
Traffic engineers compare the
existing conditions against nationally accepted minimum
standards established after many years of studies.
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 places traffic
signal improves the flow and decreases crashes, an unnecessary
one can be a sources of danger and annoyance to all who
use an intersection: pedestrians, cyclists and drivers.
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