Adaptive cruise control and forward collision warning systems can reduce harsh braking events by 67 percent.

Experience from a large scale field operational test in Europe.

Date Posted

European Large-Scale Field Operational Tests on In-Vehicle Systems: Final results - Impacts on traffic safety

Summary Information

As part of a large-scale field operational test of Advanced Driver Assistance Systems (ADAS) in Europe this project analyzed the safety and environmental impacts of Adaptive Cruise Control (ACC) and Forward Collision Warning (FCW) used by ordinary drivers in real traffic. Over 900 vehicles including cars and trucks from a range of manufacturers took part in the study which began in 2008 and included five test sites in Europe including Sweden, Germany (two test sites), Italy, and France. The following functions were evaluated:

  • Longitudinal functions: ACC and FCW (counted as one function) and Speed Regulation System (SRS): Speed Limiter (SL) and Cruise Control (CC).
  • Lateral functions: Lane Departure Warning (LDW), Impairment Warning (IW), and Blind Spot Information System (BLIS). LDW and IW were analyzed together as a bundle in cars.
  • Other functions: Curve Speed Warning (CSW), Fuel Efficiency Advisory (FEA), and Safe Human-Machine Interaction (Navigation System).

The safety study defined a target crash population for each ADAS technology and identified events within its operational scope that each technology was designed to address. Crash risk was then quantified with and without each technology. Since data associated with actual crashes was limited, surrogate measures of safety were used, such as frequency of safety critical events and changes in driver behavior. Using statistical analyses researchers estimated impacts on the target population and then extrapolated impacts to a national (EU-27) level if widely deployed.


Summary findings from the source report are shown below.

Vehicle type
Road type
Usage (portion of the total driving in treatment)
Changes between baseline and treatment in safety related measures in the FOT data. Positive numbers indicated an estimated decrease in risk when ACC+FCW was in use.
Potential reduction in the target crash population (rear end crashes)
Potential reduction in accident population per road type in EU-27
Passenger Cars
32 - 82%
16 - 42%
2.2 - 5.8%
Passenger Cars
32 - 45%
10 - 14%
0.47 - 0.65%
Passenger Cars
14 - 36%
6 - 15%
0.2 - 0.6%

Specific data collected on approximately 100 passenger cars equipped with commercially available ACC and FCW systems showed more positive impacts. Result of a comparison of vehicle performance during a three month baseline and a nine month treatment phase found the bundled system increased average time-headways between vehicles by 16 percent on motorways. Correspondingly, the number of critical time-headways (less than 0.5 seconds) was reduced by 73 percent, and number of harsh braking events decreased by 67 percent.
Goal Areas