Tailgating

Abstract

Among the causes of rear end crashes is tailgating (following too closely). (In this report, tailgating does not refer only to deliberately aggressive close following, the driver may consider the close distance to be appropriate.) Calculations about how tailgating can lead to rear end crashes are presented. A distinction is made between conditions in which improved braking performance will and those in which it will not reduce the likelihood of a rear end crash. Short gaps between one vehicle and the next are very common in ordinary driving. Because of the possibility of a disturbance in flow being amplified as it passes from one vehicle to another, drivers bear a collective responsibility to vehicles behind them to try to dampen rather than amplify disturbances. Evidence from rear end crashes that were investigated in depth by staff at CASR (Centre for Automotive Safety Research, University of Adelaide) is that inattention in various forms is a more frequent cause than tailgating. (It is noted that methods of classification of rear end crashes are surprisingly coarse and not very helpful for devising remedial measures.) Potential measures to counter tailgating are discussed: advisory signs, markings on the road surface, enforcement by the police, a futuristic proposal for enforcement by the public, and improvements to the vehicle. There is reason to think that each of these would meet with some success.