Auditory Intelligent Speed Adaptation for Long-Distance Informal Public Transport in South Africa

Informal transport refers to the collective passenger road transport industry with little or no regulatory control of its operations, usually characterized by unplanned and ad-hoc service delivery. The notoriously dangerous informal transport industry in South Africa - dominated by minibus taxis - has been shown to disregard the posted speed limit on long-distance trips. Not only do they frequently exceed the differentiated speed limit imposed on minibus taxis, but also the speed limit imposed own normal passenger vehicles. This paper evaluates the impact of an auditory Intelligent Speed Adaptation (ISA) intervention, applied at various intensity levels, on the speeding behavior of this seemingly intransigent mode of transport. The experiment evaluates the behavior on the R61 between Beaufort West and Aberdeen. We evaluate the speeding distributions, speeding frequencies, speed percentiles, mean speeds, and the statistical relevance of key metrics. We find that the auditory intervention has a clear impact on speeding behavior, both when applied at an audible level that can be drowned out by a radio, and even greater impact at a loud level. The impact on speeding is significant, with speeding frequency (both time and distance) reducing by over 20 percentage points.