Cost Benefit Analysis of Intelligent Speed Adaptation
This paper details a cost–benefit analysis of intelligent speed adaptation (ISA) in Australia. The extent of the problem of speed related crashes in Australia is estimated from mass crash data. An analysis of the benefits of ISA is conducted by describing the effect of the differing levels of ISA (advisory, supportive and limiting) found in the UK-ISA trial on the distribution of speeds of vehicles. These effects are applied to distributions of speeds measured on Australian roads and the resulting distributions are multiplied by Kloeden’s risk curve for free travel speed to determine the benefits of ISA. The costs of dedicated in-vehicle ISA devices and digital speed limit map production and maintenance are estimated. Economic analyses are conducted on implementation scenarios, including installing ISA on all vehicles, new vehicles and fleet vehicles. Navaid devices are also considered. ISA was determined to be able to reduce injury crashes by 7.7%, 15.1% and 26.4% for advisory, supportive and limiting ISA respectively. In monetary terms this equates to $1,226 million per year saved with advisory ISA, $2,240 million per year saved with supportive ISA and $3,725 million per year saved with limiting ISA, if fitted to all vehicles. Limiting ISA produced the highest benefit–cost ratio (BCR) and break even price. The new vehicles scenario generally produced the highest BCR.