FAQ: Intelligent Speed Assistance (ISA)

Intelligent Speed Assistance (ISA) is the term given to a range of devices that assist drivers in choosing appropriate speeds and complying with speed limits. Intelligent Speed Assistance technologies bring speed limit information into the vehicle. Drivers receive the same information that they see (or sometimes miss seeing) on traffic signs through an onboard communication system, helping them to keep track of the legal speed limit all along their journey. Information regarding the speed limit for a given location is usually identified from an onboard digital map in the vehicle. Other systems use speed sign reading and recognition.

The information is then communicated to the driver in any of the following three ways: informing the driver of the limit (advisory ISA), warning them when they are driving faster than the limit (warning ISA) or actively aiding the driver to abide by the limit (assisting ISA).

All ISA systems that are currently being used in trials or deployment can be overridden if wished by the driver. In contrast to ISA, a speed limiter is a device used to limit the top speed of a vehicle. For some classes of vehicles in the EU they are a statutory requirement. Buses and coaches (M2 and M3 categories) are limited to maximum 100km/h, while heavy goods vehicles (N2 and N3 categories) are limited to maximum 90km/h.