Vehicle speed-limiter benefits 'considerably outweigh costs'

Some form of speed-limiter system for cars could be introduced in the UK following a successful trial of the scheme.

The Government-backed trial showed the system - known as Intelligent Speed Adaptation (ISA) - had good road safety potential.

Earlier work had already demonstrated the viability of ISA technology. The latest project, carried out for by the University of Leeds and MIRA Ltd, looked at driver behaviour.

Now the Department for Transport (DfT) has said it will work with vehicle manufacturers, local authorities, insurance companies and others to consider what steps should be taken to support the future availability of the technology.

ISA is an in-car system that provides information on the speed limit for the road being travelled on.

It can come in three forms. The advisory ISA involves information that can be used to display the current speed limit inside the vehicle and warn drivers when they are speeding.

The voluntary ISA can be linked to the vehicle engine and perhaps to the brakes to curtail speed to the speed limit for the road while allowing the driver to override the system. The mandatory ISA can be linked to engine and brakes without the possibility of an override.

For these trials, twenty cars were equipped with ISA technology that could match the vehicle position to a stored map of speed limits and display the current limit to the driver. Drivers were recruited in two age bands and from both men and women. They drove the cars for six months: one month without ISA, four months with it and a further month without. Four successive field trials were carried out with fleet and private motorists in urban Leeds and a largely rural part of Leicestershire. There were also separate truck and motorcycle trials involving one vehicle each.

Separate reports have been published for all six trials.

The researchers say the car trials demonstrated that ISA can deliver substantial reductions in excessive speed. The overridable ISA that was used reduced the amount of speeding among every category of user and on every road category except the 60mph rural roads where there had been comparatively little speeding anyway.

Analysis based on accident prediction models and two different ISA implementation scenarios ('market-driven' and 'authority-driven') showed that whatever combination of models was used, the economic benefits from reducing deaths and injuries would considerably outweigh the costs.

The DfT said the trial found that ISA had the potential to reduce the number of deaths and injuries on our roads and so confirmed the department's view that ISA could be a useful road safety feature for drivers who wish to use it.

The DfT went on: "We are clear that any future use of ISA is taken forward by the motoring industry in response to consumer demand, just as with other technologies available for consumers to purchase if they so choose.

In the majority of conditions, participants considered driving with ISA safer than driving without the system. However, participants felt at increased risk with ISA when overtaking or driving in fast-moving traffic.

A total of 54 per cent of participants would be willing to have ISA installed in their vehicles if its use was voluntary. Participants' willingness to pay for the system ranged from paying nothing to £500. On average participants would be willing to pay £111.

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