Roadway departure
hazards
Over one-third of all traffic
fatalities (over 15,000 in 1998) occur when a vehicle leaves the road. Vehicles
often hit roadside obstacles, such as trees, utility poles, embankments, guardrails,
ditches, curbs, culverts, sign or light posts, bridge supports, and mailboxes;
they may also roll over after leaving the road. In rural areas, the situation
is even worse—two-thirds of all traffic deaths are caused by "run-off-the-road"
crashes.
Two aspects of this national safety
problem are particularly challenging: keeping drivers on the road and protecting
drivers when they do leave the road. To reduce road departure crashes, community
leaders need to consider ways to keep drivers on the road and protect them if
they do leave the roadway. If there is a pattern of vehicles leaving the
road, community leaders should work with their transportation professionals to
investigate the reasons for roadway departures and assess the impact of collisions
with roadside obstacles. An analysis of roadside obstacles at run-off-the-road
crash sites is essential to determining if they present significant dangers.
Keeping Drivers on the Road
Rumble
strips are one of the most effective ways to keep drivers on the road. More visible
signs, pavement markings, skid-resistant pavement, and better lighting have proven
to be particularly effective in keeping drivers on local roads.
Rumble strips dramatically reduce crashes on the Pennsylvania Turnpike.
Overview
Special rumble strips, equipped with a Sonic Nap
Alert Pattern (SNAP), produce a distinct warning sound and vibration that alert
drivers whose vehicles are drifting off the roadway. In 1990, SNAP strips were
installed on all 506 miles of the Pennsylvania Turnpike. After 1991, SNAP strips
and recessed reflective pavement markers were routinely installed in new roadway
segments on the Turnpike.
Results
After
the Pennsylvania Turnpike Commission installed the shoulder SNAP strips in 1990,
drift-off-the-road crashes decreased by 65% per month. Six years later, Turnpike
officials credited the rumble strips with reducing the crash rate by 2.3 crashes
per 100 million vehicle miles, or 100 crashes per year.
Contact
Planning and Programming Department, PA Turnpike
Commission, (717) 939-9551
Protecting Drivers When They
Leave the Roadway
Utility poles can be serious hazards
when they are placed too close to roadways. These poles get in the way, drivers
have little room to maneuver around them, and collisions occur. The example that
follows shows how one community effectively addressed this problem.
King County, WA, reduces the number of off-the-road crashes.
Overview
Officials in King County, WA, decided to address
their utility pole problem when the community was faced with roadside losses and
rising liability claims resulting from collisions with poles. The Public Works
Department inventoried the roads under its jurisdiction, rating them for roadside
safety. Public Works staff then reviewed accident reports to identify utility
poles hit by motorists and created a monitoring system for poles hit more than
once. Utility companies whose poles had been hit twice received letters from the
county, noting specific poles as hazards.
Results
Utility
companies were given the option of removing, moving, or protecting the poles with
safety devices. After meeting with utility company risk managers, legislation
was enacted that outlined where and how poles should be placed on roadways. Additionally,
the legislation required that a licensed civil engineer, with expertise in safety,
sign all utility company plans for replacing more than one pole, thus certifying
that county requirements had been met.
Contact
Traffic Engineering, King County Department of Public Works, (206) 296-6596,
Ext. 3762
