An Investigation into the Demand for Intelligent Speed Adaptation (ISA) Systems in the United Kingdom

An Investigation into the Demand for Intelligent Speed Adaptation (ISA) Systems in the United Kingdom


S Hess, K Chorlton, S Jamson, M Wardman, ITS, University of Leeds, UK



Intelligent Speed Adaptation (ISA) is a system which uses information and communications technology to provide speed limit information on a vehicle?s dashboard. The typical means to do this is with a digital road map of the kind used in satellite navigation systems, but with the important difference that it also contains speed limit data for very road. When the map is combined with current position information from a GPS (Global Positioning System) receiver, then the ISA system can display the speed limit and warn the driver if the vehicle is being driven above the speed limit. This is advisory ISA. The same information about speed limit can be linked to the vehicle?s engine management system to provide voluntary (overridable) ISA or even mandatory (non-overridable) ISA.
This paper reports on a recent UK study looking at how to encourage increased demand for ISA systems. Specifically, we made use of a Stated Choice (SC) survey which presents respondents with a number of scenarios, each time involving the choice between a voluntary and a mandatory system. Given the results of initial focus groups, different survey designs were created for three types of vehicle purchaser.
The first group contained those respondents likely to buy a mandatory ISA system, where these drivers received a SC survey where both systems were offered at a cost to the driver. The second group contained those respondents likely to buy a voluntary system, where these drivers were required to pay for voluntary system but received incentives to buy a mandatory system. The final group contained those respondents unlikely to buy either system, where both systems were offered with discounts and incentives to encourage drivers to purchase an ISA vehicle.
Factors influencing decisions to buy that were investigated were purchase price, insurance discount and annual tax discount. Incentives to use voluntary ISA that were studied were a fuel rebate or cash back on a driver?s insurance premium for every mile travelled with the system activated. A total of 1,487 interviews were carried out across Great Britain in randomly selected areas and at addresses randomly selected within each area. Only one driver was interviewed per household.
The data collected using the different surveys were analysed using state-of-the-art discrete choice models, allowing for the anticipated large variations in preferences across respondents. The analysis showed that, as expected, the main differences were between the three groups already identified prior to the administration of the survey questionnaire. However, even within the groups, there were major variations such that models of choice between the two systems performed much better when sub-classes within the groups were considered.
The final picture emerging from our study is one of some groups with very entrenched positions (both pro and con) who are not really amenable to persuasion by means of incentives. On the other hand, there are other groups who are amenable to subsidy, particularly on purchase price and fuel cost, or who would be willing to purchase an ISA system if the cost were not too high. It is interesting to note that the analysis revealed that, while there are very significant variations in sensitivities and preferences, these cannot easily be linked to socio-demographic attributes of the respondents. Thus it is not necessarily the case that young male respondents have a strong objection to ISA while older respondents with more expensive cars have a more positive attitude.


Association for European Transport