Rumble strip
From Free net encyclopedia
Rumble strips are strips of painted, ridged or grooved road surfaces to warn drivers when they stray from their lanes onto the hard shoulder. They are also used to warn drivers of upcoming hazards that require drivers to slow down, such as a sharp curve. On rural highways, they sometimes indicate that a stop sign is coming up, especially if there have been several miles or kilometers of stop-free traveling before that point. The strips alert the driver both by causing a tactile vibration and the namesake audible rumbling. Occasionally in the UK, they may be painted horizontally across the road in groups of 5 as a traffic calming method, to slow drivers down.
Rumble strips were invented by the Pennsylvania Turnpike Commission in the late 1990's as a part of the Sonic Nap Alert Program (SNAP) after a survey from the 1980's revealed that the number one contributor to PA Turnpike accidents were DOR accidents, or Drift-Off-Road accidents. The first section of test roadway is located just east of Breezewood, PA. After their installation, the first five SNAP project roadways showed a 70% reduction in DOR accidents.