Intelligent Speed Adaptation (ISA)

What is ISA?

ISA is a system which informs, warns and discourages the driver to exceed the statutory local speed limit. The in-vehicle speed limit is set automatically as a function of the speed limits indicated on the road. GPS allied to digital speed limit maps allows ISA technology to continuously update the vehicle speed limit to the road speed limit. There are three types of ISA:

What road safety problem does ISA address?

Excess speed contributes to around 30% of fatal crashes [51]. Typically 40% to 60% of the drivers exceed the limit. Results from a wide range of studies indicate that reducing average speeds by just 1km/h can result in a 5% reduction in fatal crashes.

How effective?

The EU-funded and SRA co-ordinated project PROSPER looked into ways that advanced assisted driving technology and technology relating to speed limitation devices can improve safety, and also at the barriers for the implementation of ISA. The PROSPER project calculated crash reductions for six countries. Reductions in fatalities between 19-28%, depending on the country, were predicted in a market-driven scenario. Even higher reductions were predicted for a regulated scenario – between 26-50%. Benefits are generally larger on urban roads and are also larger if more intervening forms of ISA are applied [11]. Trials with ISA have been carried out in ten European countries: Austria, Belgium, Denmark, Finland, France, Hungary, The Netherlands, Spain and Sweden [19]. An earlier study in the Netherlands showed that ISA could reduce the number of hospital admissions by 15% and the number of deaths by 21% [35]. Research has shown that ISA and physical measures to reduce road speed are complementary rather than competing methods [39].

Benefits to cost?

Benefit to cost ratios ranging from 2.0 to 3.5 and 3.5 to 4.8 were calculated in the PROSPER project for the two scenarios: market driven and regulation driven. The costs were based on the premise that by 2010, all new vehicles will come with a satellite navigation system [11].

Other benefits?

Other ISA benefits have been identified as fuel savings, CO2 savings and the potential to reduce journey time (managed motorways; reduction in incidents).

Who uses ISA now?

While trials and further experimental studies are being carried out in Norway, the Netherlands and the UK, large-scale demonstration has only been implemented in Sweden. Sweden’s National ITS Strategy for 2006-2009 targeted better speed compliance as one of four ITS road safety initiatives national and internationally with its Nordic partners. Sweden sees the establishment of speed limit data base, the targeting of the road transport industry and the introduction of in-house policies as essential first steps.

Future use?

Different trials using informative and supportive systems across Europe have shown that approximately 60-75% of users would accept ISA in their own cars. A MORI poll in the UK carried out for the FIA Foundation in 2002 indicated 70% support for warning ISA in urban areas with 58% in support of non-overidable limiters on residential streets if that meant road humps would be removed. One has shown that 73% of drivers reported being more positive towards ISA after using it [3]. Lahrmann, Madsen and Boroch [32] reported that 15 out of 20 drivers became more favourable to using ISA after experiencing the system

Next steps for implementation?

While positive benefits to cost have been identified for ISA, number of criticisms of ISA have hindered widespread implementation. A review - Intelligent speed assistance – myths and reality – discussed ‘myths’ regarding ISA and argues that ISA (and Speed Alert) technologies can work reliably [19].

An EU-funded SpeedAlert project co-ordinated by ERTICO was set up in 2004 to harmonise the in-vehicle speed alert concept definition and investigate the first priority issues to be addressed at EU level, such as the collection, maintenance and certification of speed data.

While there is considerable public support for ISA, an implementation strategy is needed to speed up the process of implementation of ISA in vehicles [39]. This should include the development of speed limit maps by European, national and regional authorities (to date, Sweden and Finland have established speed limit databases although these are under development in the UK and the Netherlands). Also, awareness of ISA / Speed Alert has to be created. Authorities and organisations (e.g. fleet owners) can act as forerunners by implementing ISA in their vehicle fleets. Last but not least, further harmonisation activities are needed on the international level.