road safety feature by means of change in tyre noise
Rumble strip Rumble strips, also known as sleeper lines, alert strips, audible lines, sleepy bumps, wake up calls,[1] growlers, drift lines, and drunk bumps, are a road safety feature to alert inattentive drivers of potential danger, by causing a tactile vibration and audible rumbling transmitted through the wheels into the vehicle interior. A rumble strip is applied along the direction of travel following an edgeline or centerline, to alert drivers when they drift from their lane. Rumble strips may also be installed in a series across the direction of travel, to warn drivers of a stop or slowdown ahead, or of an approaching danger spot.
Safety car The first use of a safety car in Formula One is reported to have taken place at the 1973 Canadian Grand Prix, where a yellow Porsche 914[5][6] was called for duty following various incidents under treacherous weather conditions. Controversially, on that occasion, it took several hours after the race to figure out the winner and final results since the safety car driver had placed his car in front of the wrong competitor thus causing part of the field to be one lap down incorrectly.[7]