ISA, an abbreviation that stands for Intelligent Speed Assistance*, is one of the driver assistance systems that has been mandatory in all new passenger vehicle models across Europe since July 2022.

So although (some form of) ISA is now mandatory built into all new car models, many drivers have yet to experience ISA. So they have yet to accept this new technology and learn to drive with it. This is important, because only with a high level of acceptance can the intended goals of ISA be achieved.

Meanwhile, there is ample evidence that the acceptance rate of ISA can be high. However, this is especially true when the system works perfectly. Previous research has also shown that drivers have higher standards for accepting technical failure in vehicle systems than for their own vehicle control and driving style. And this is where things falter, when it comes to the use and acceptance of ISA. In fact, at the moment, ISA does not work perfectly, and many a driver turns off the system.

Speed is one of the most important basic risk factors in traffic. The faster a car is driven, the greater the risk of (serious) accidents and the higher the emissions. Policy therefore increasingly focuses on preventing excessive speeds and speed differences in road traffic. The driving assistance system ISA, Intelligent Speed Assistant, is one of the technological solutions that can contribute to this. ISA comes in many guises, from informative (via smart technology, the driver is informed of the prevailing speed limit) to coercive (the car is physically restricted from driving faster than the speed limit).

Meanwhile, there is ample evidence that the acceptance rate of ISA can be high when the system works perfectly.

Practice, however, is recalcitrant. Driving with ISA depends on many systems, and both the in-car system and the many complex systems required to provide the underlying information can fail or transmit incorrect information. The active limiting of speed by ISA is also perceived and rated differently by drivers. All this hinders the acceptance of ISA, preventing all the positive effects.In project ACTI-I, based on interviews with experts, potential users and test subjects, a literature review, and research on the accuracy of digital maps, the impact of technical failure on the acceptance of ISA was investigated.

The report presented the methodology, findings, and key recommendations. The main conclusion is that the potential of ISA for increasing road safety is high because the system, when functioning properly, is expected to be used by a large proportion of drivers.

However, the technical state-of-the-art is not currently advanced enough to realize this potential. In particular, the digital infrastructures required for high-quality data in the system are not sufficiently well developed and/or coordinated. The driver notices the adverse and sometimes even dangerous consequences of this while driving, which obviously does not help the adoption of the system.