This study evaluated the potential casualty benefits and fitment costs of several in-vehicle safety technologies designed to help drivers avoid the most common types of passenger vehicle crashes (rear-end collisions, pedestrian-vehicle conflicts, and lane departure and run-off-road crashes).
The findings were based on an analysis of national crash data in the United Kingdom. After identifying relevant crashes, the results were scaled to national level and the magnitude of impact on the number of relevant crashes was estimated based on a literature review of system effectiveness.
Advanced Emergency Braking Systems (AEBS)
Passenger car AEBS have been designed with forward facing sensors (i.e., lasers or radar) to determine closing speeds and vehicle headways, and provide in-vehicle warnings and automated braking features to mitigate crash potential.
Two primary designs have been developed.
- AEBS-1 have been designed to mitigate rear-end collisions with stationary targets with closing speeds of 40 mi/hr or less
- AEBS-2 have been designed to mitigate rear-end collision with a vehicle in front regardless if it is stationary or not.
Assuming that current costs for AEBS would be less if deployed with economies of scale, system unit costs (to manufacturers) were estimated at 100 to 550 British pounds per vehicle. Applying these costs to the 2.2 million assumed new car registrations in Great Britain, and comparing these data with the casualty costs reported by the Department of Transport (2010) it was estimated that 6 to 40 percent of the target population of casualty costs could be addressed by the technology and the following benefit-to-cost estimates were calculated. Note that the estimates below are steady-state ratios that represent full casualty cost savings only after the entire fleet has been equipped. The system fitment costs represent only new registrations. Benefit-to-cost ratios would likely be less prior to 100 percent fleet penetration.
|Per Vehicle Costs (British Pounds)||Total Annual Cost (British Pounds)||Total Annual Savings (British Pounds)||Benefit-to-cost ratios|
|AEBS-1||100 - 500||220 million -
|80 million -
|0.07 - 2.78|
|AEBS-2||125 - 550||275 million -
|84 million -
|0.07 - 2.23|
Overall, the cost effectiveness of AEBS was limited by its relatively high system costs. Researchers noted that the system was most effective when brakes were applied early in each time-to-collision scenario. Early activation, however, resulted in a higher frequency of unnecessary automated brake activations which could hinder product acceptance.
Second Generation AEBS With Pedestrian Detection
Development of second generation AEBS systems use forward facing sensors (i.e., lasers or radar) as well as optical systems to improve detection of pedestrians. Automatic braking power can be applied 0.6 sec, 1 sec, or 2 sec before impact with a pedestrian. The assessment from the Department of Transport indicated these systems would be applicable to 20 to 40 percent of the target population where casualty costs applied.
- Benefit-to-cost ratios for these systems ranged from 0.19 to 1.04 as a steady-state estimate with 100 percent fleet penetration.
Lane Departure Warning (LDW) System
LDW Systems for passenger vehicles provide in-vehicle warnings in the event of an unintended lane departure that could potentially result in a head-on collision, side swipe accident, or a run-off road crash. Most systems use forward looking video while others use infra-red sensors or laser scanning technologies. These systems are typically activated when the vehicle exceeds a predetermined speed threshold (56 to 80 Km/hr for passenger cars) and only provide drivers with a warning and do not take automated action. Audible warnings can include simulated rumble strip noises, and hepatic warnings can include a vibrating driver seat or steering wheel.
- Data collected from field operational test results in the United States were used for the analysis and researchers estimated that LDW systems have potential to benefit 12 to 31 percent of the target population where casualty costs apply.
- In combination with the per vehicle system costs in Great Britain benefit-to-cost ratios for LDW systems ranged from 0.25 to 2.12 as a steady-state estimate.
- Additional analysis indicated that lane departure warning in the United Kingdom would reduce the number of fatalities by 15 to 60 per year, and reduce the number of serious injuries by 578 and 1,581 per year with 100 percent fleet penetration.
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