The estimated benefit-to-cost ratio (BCR) from ISA-UK is 7.4 for a scenario in which the authorities actively promote ISA deployment through regulation (Lai et al., Cars with intervening ISA score more highly than cars with an advisory ISA. Extra points are also given for vehicles that combine map-based ISA with a camera-based sign recognition system. The conclusion was: “The most effective driver support system is ISA” (page 50).