Intelligent speed assistance

Intelligent speed assistance (ISA), or intelligent speed adaptation, also known as alerting, and intelligent authority, is any system that ensures that vehicle speed does not exceed a safe or legally enforced speed. In case of potential speeding, the driver can be alerted or the speed reduced automatically. Intelligent speed assistance uses information about the road to determine local speed limits. Information can be obtained from knowledge of the vehicle position, taking into account speed limits known for the position, and by interpreting road features such as signs. ISA systems are designed to detect and alert a driver when a vehicle has entered a new speed zone, or when different speed limits are in force according to time of day and conditions. Many ISA systems also provide information about driving hazards (e.g. high pedestrian movement areas, railway crossings, schools, hospitals, etc.) and limits enforced by speed and CCTV cameras at traffic lights. The purpose of ISA is to assist the driver to maintain a safe speed. ISA was born in France when Saad and Malaterre (1982) carried out their study of driver behaviour with an in-car speed limiter. Actually, they did not really test Intelligent Speed Adaptation, because the system did not automatically set the correct speed limit; instead drivers had to set the limiter themselves, and, rather like a cruise control, they could set it as they chose. After that there was roughly a ten-year gap until research on ISA was resumed in Sweden in the early 1990s. There followed a series of projects in Sweden, culminating in the large-scale trial of 1999 to 2001, when there were close to 5000 ISA-equipped vehicles on Swedish roads (Biding and Lind, 2002). Most of these vehicles were equipped with an informative or warning version of ISA, but a few hundred used an intervening system, being fitted with a haptic throttle, whereby the accelerator pedal became stiffer when the speed limit was exceeded. A kick-down function was provided to allow drivers to overcome this resistance.