Results of a field operational test of a context aware intelligent speed adaption system

In the past, several field studies have proven the technological feasibility of ISA-systems. Most of these studies used warning or assisting ISA-systems to influence drivers. Until now, studies that focused on a restricting (closed) method have only been executed on relatively small testing areas with slow speed zones. This report presents the results of a field test with restricting ISA on public roads with multiple speed zones. During a period of 3 weeks, 10 taxis used a system that is referred to as Context Aware Intelligent Speed Adaptation (CAISA). The system matched the vehicles’ maximum speeds to legislated speeds of the roads they were driving on. Additionally, vehicles were limited in the maximum amount of revolutions per gear. The objective of this report is to gain insight into the acceptance, commercial application and map updating possibilities of CAISA. In order to do so, driving behaviour, in terms of acceleration and speeding, of 18 chauffeurs was monitored. The test results indicate that CAISA generally leads to slower accelerations. A comparison between the logged speed before and after the installation of CAISA showed that the system can reduce the amount of speeding-kilometres with at least 18[%]. The acceptance, safety and impact on driving behaviour of CAISA were determined by means of a questionnaire that was filled out by the participants before and after the field test. Although the sample group was too small to provide statistically significant conclusions, the results of the research indicate that the acceptance of CAISA under taxi drivers is low. After the trial, acceptance decreased even further. According to the subjective opinion of chauffeurs, CAISA decreases traffic safety, whereas the objective results of the field test indicate that CAISA improves traffic safety. Chauffeurs indicate that CAISA enforces slower acceleration, less use of the gas pedal, less breaking and a lower average speed. The economic feasibility of CAISA was determined by calculating the profitability based on the determined fuel savings. CAISA proved to be profitable if a vehicle drives more than 91,287 [km/year]. Under the experimental conditions CAISA decreased the fuel consumptions by 6.24[%]. Vehicles that experienced only engine revolution limitation saved 14.25[%]. However, theoretically an enforced maximum speed is not likely to cause extra fuel usage. The collected data show a change in gear switching behaviour when CAISA was active. This could provide an explanation for the found differences. Further research is needed to confirm this hypothesis. An analysis of the involved stakeholders, available techniques and a set of predefined criteria led to the conclusion that currently digital speed maps could best be updated by an independent low-tech process. The system that was considered most suited to be implemented has got the following features: ‘Collection of legislated speeds through manually driven GPS-cars’, ‘determination of a vehicles position by making use of inexpensive GPS-receivers’ and ‘map updating through location based WIFI’. The results of this experiment can be regarded as a proof that CAISA is technologically feasible on a local scale, without the support of costly (inter)nationally-coordinated systems.Transport & PlanningCivil Engineering and Geoscience