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. History After ISA regulation entered into force in the EU on 8 July 2022, a speed limiter ISA law entered into force in the UK on 6 July. Regulation does not enter into force the same day due to Brexit. Terminology Intelligent speed adaptation is the terminology of the British Standards Institute, while the EU refers to intelligent speed assistance, in regulation (EU) 2019/2144 of the European Parliament. Active and passive ISA Passive systems warn the driver when the vehicle is travelling in excess of the speed limit, while active systems slow the vehicle's speed to conform with the speed limit. Passive systems allow the driver to make a choice on what action should be taken. These systems usually display visual or auditory cues and warnings, which and may include tactile cues such as vibration in the accelerator pedal. Some passive ISA technology trials have made the accelerator pedal stiffer to alert the driver. Most active ISA systems allow the driver to override the ISA when deemed necessary; this is thought to enhance public acceptance and safety, but leaves a significant amount of speeding unchecked. Both active and passive ISA systems can serve as on-board vehicle data recorders, retaining information about vehicle location and performance for later checking and fleet management purposes. Speed and location determination and verification There are four types of technology available for determining local speed limits on a road and the