Speed regulating Effects of Incentive-based Intelligent Speed Adaptation in the short and medium term
Despite massive improvements in vehicles’ safety equipment, more information and safer road network, inappropriate road safety is still causing that more than 250 people are killed and several thousands injured each year in Denmark. Until a few years ago the number of fatalities in most countries had decreased while the amount of traffic increased. However, this trend has been replaced by a more uncertain development towards a constant or even somewhat increasing risk.
Inappropriate speeding is a central cause for the high number of fatalities on the roads. Despite speed limits, speed limit violating driving behaviour is still widespread in Denmark. Traditional solutions to prevent speed violation have been enforcement, information, and enhanced road design. It seems, however, hard to achieve sufficient further road safety on the basis of these solutions, while additional solutions known as Intelligent Transport Systems, and more particularly Intelligent Speed Adaptation (ISA), can be seen as a central solution towards a safer road network.
ISA can be informative. It informs the driver about the speed limit. It can also give warnings if the speed limit is violated. Also, ISA can be recording, which means that driving behaviour is logged and driving data can be used for a number of purposes. It can also be incentive. Incentive ISA is based on recording ISA but is supplemented with a kind of reward or penalty system associated with driving behaviour. Moreover, ISA can be intervening, so it can prevent speed violations physically.
More than 30 ISA trials involving different ISA equipment have been carried out, and almost all trials have shown significant effects on driving behaviour towards fewer speed limit violations. Estimation of safety effects showed various results and the reduction in the number of fatalities was estimated to be as high as 37 to 42% if ISA was fully implemented. Despite convincing effects of ISA in short term, it was found that the effect of ISA decreased over time and that exposed road users, such as young novice drivers, were underrepresented in most trials.
Could it be that an economic incentive linked to driving behaviour could be the determining factor that might open the market to ISA on a large scale? This was the underlying idea when two Danish ISA trials were developed involving an incentive-based ISA system aimed at the target groups of young drivers and commercial drivers, on a commercial basis.
The trials were Pay As You Speed (PAYS) and Intelligent Speed Adaptation Commercial (ISA C). In PAYS the size of the insurance rate would depend on the driver’s amount of speeding. Thus no speeding would result in a 30 per cent reduction on the car insurance rate. Focus in the thesis has mainly been on PAYS.
The ISA consisted of a display with loudspeakers, a small computer and a GPS antenna. Feedback was given, if the speed limit was exceeded by more than 5 km/h. The display showed the actual speed limit, any penalty points received due to speeding during the on-going trip, and the number of penalty points received during the previous test period. Also, auditory feedback was given every six seconds in the case of speeding. From the third and subsequent warnings penalty points worth DKK 0,50 was added to each warning. The driver could see any penalty points on a personal webpage.
The first 1.5 months - a baseline period (ISA was passive) was used to assess each participant’s normal driving behaviour. The discount was independent of the driving behaviour during this period. During the next 4.5 months, the participants were randomly divided into four groups, each driving under different ISA conditions. A control group continued like in baseline. An incentive group continued with no real-time feedback. However, penalty points would result in reduced discount on the insurance rate. An information group was given only information and driving behaviour did not affect the discount. In a combination group, the participants received information and any reduced discount in case of speeding. The combination treatment was the main mode for the trial, and after the 4.5 months, all participants drove in this mode.
The aim of this thesis was to establish how informative and warning ISA in combination with incentives for avoiding speeding affect driving behaviour among exposed road users (18-28 years old drivers) in short term and in medium term after activation of ISA. The effect was studied on the basis of the Danish ISA trial PAYS.
Short term means 0-1.5 months after ISA activation, while medium-term means 3-4.5 months after ISA activation. Regarding short-term effects, it was found that the combination of informative and incentive ISA resulted in statistically significant less speeding and less speed variation than did either of them. Moreover, it was found that incentive without informative ISA worked significantly better than informative ISA without incentive. These results hold good, in general, regarding 50 and 80 km roads, which is equivalent to 78% of the data studied. On 110 and especially on 130 km roads the pattern is more confounding.
In the medium term the differences between the different ISA treatments became even more substantial. The effect of informative ISA differed markedly but in general decreased over time. Regarding incentive the effect appeared and remained although, in most cases, the effect of combination was significantly bigger than of incentive. Hence, the overall conclusion is that informative and warning ISA combined with an economic incentive for avoiding speeding has a significant and lasting effect on driving behaviour. Also it is found that this combination works significantly better than do each of the parts of the ISA conditions.