If a street has major sight obstructions at intersections, people won't
be able to see each other and crashes may result. Problems most often occur
on residential streets where, for example, someone might plant a shrub at
an intersection and street department personnel may not notice it for years.
Bottomline: sight triangles at intersections should be kept clear.
Sight triangles are areas defined by a driver's eye, the location of
a visual barrier, and a potential hazard. Since residential street collisions
typically happen at intersections, the most important sight triangles tend
to be at such locations and keeping these triangles free of visual obstructions
is most critical there.
The dimensions of the triangle depend on the situation. for instance, sight
lines for motorists approaching a stop sign on a residential street need
not be as long as the sight lines for motorists approaching an uncontrolled
intersection. The diagram below shows these two alternatives.
Typically, there are two parts to a successful strategy. First, there
must be an ordinance defining the triangles and the procedures that will
be used to keep them clear. Second, there must be education and enforcement.
Someone must be responsible for letting people know what the law says, for
checking out citizen complaints, for looking for problem locations, and
for making sure problems are fixed.
The primary benefit is an improvement in neighborhood safety and, potentially,
a reduction in residential street crashes. Many car/bicycle crashes -- particularly
those involving youngsters -- happen on residential streets and some critically
important crash types can be avoided if motorists see young bicyclists in
time.
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