The evaluation and testing of mobile ITS interventions on speed compliance in the minibus taxi industry of South Africa

[摘要] ENGLISH ABSTRACT: Informal public transport in South Africa, dominated by minibus taxis is noted for poorcompliance, and has been shown to disregard posted speed limits on long-distance trips.They go as far as driving over the di erentiated speed limit of the lighter passenger vehiclesused for private transport. This work compares and evaluates improvements in their speedcompliance using two renowned interventions: automated Average Speed Enforcement(ASE), and auditory Intelligent Speed Adaptation (ISA). The feasibility of fuel economyexisting as a self-regulatory incentive for speed compliant driving is investigated, togetherwith the impact of each intervention on fuel consumption rates. The mainndings werethat with minibus taxis, ASE is not well understood and needs ISA as a complementaryintervention, and safe driving can increase driver remuneration from fuel costs.Average Speed Enforcement is an emergent alternative to instantaneous speed enforcementto improve road safety. This study involves a mixed methods approach in understandingdriver response to the system on the R61 Between Beaufort West and Aberdeenin South Africa. A spatio-temporal quantitative study of speed compliance is conducted.Various speed metrics are measured prior to, and during enforcement, and ASE impacton crash risk and injury severity is also examined. These measurements are taken on theenforcement route and on control routes having similar characteristics. Two main modesof transport in the region are considered, namely minibus taxis and passenger vehicles.A qualitative study is also conducted to evaluate the relationship between speed complianceand understanding of the system. Results show that for passenger vehicles, the ASEsystem led to a reduction in mean speed on the enforcement and adjacent control routes.However, ASE appears to have no inuence on minibus taxis, which could be linked tolimited understanding on ASE operation.This study also tests and evaluates the impact of an auditory ISA intervention, appliedat various levels, on the speeding behaviour of the seemingly intransigent minibus taxiindustry. The experiment evaluates the same ASE section on the R61, to which theminibus taxi drivers were seemingly impervious. Various speed metrics, as well as theirstatistical relevance and the e ect sizes are evaluated. Results show that the auditory ISAintervention has a clear impact on speeding behaviour, both when applied at an audiblelevel that can be drowned out by a radio, and even more so at a loud level. The impact onspeeding is signi cant, with speeding frequency (both time and distance) reducing by over20 percentage points. Also, although the drivers showed little or no behavioural changewhen driving on the ASE route, introduction of the ISA system resulted in signi cantchanges bringing violation frequencies down to 47.4% from 81.2% on the enforcementroute. These changes brought about lower fuel consumption rates especially with the ISAsystem, and drivers can increase their remuneration by a minimum of about 120% and byup to 214% from the fuel budget if they drive safely.

[发布机构] Stellenbosch University