TABLE OF CONTENTS Cooperative vehicle-highway systems can provide warnings to drivers at high-risk areas for situations that cannot be detected by onboard vehicle sensors. These may be fixed hazards such as curves, dynamic hazards such as slippery road conditions or a disabled vehicle ahead, or even the presence of animals along the roadway detected by special sensing systems [24].
In Japan, AHSRA has analyzed crash situations which can be addressed by CVHS, formulated requirements, prototyped systems, defined safety and reliability performance goals, established evaluation methods, and conducted field operational testing.
Curve Speed Warning [25 , 26 ] As described in Chapter 6, AHSRA has implemented CVHS techniques for curve speed warning on particular road sections known to be hazardous.
Unseen Obstacles AHSRA has also integrated the automatic detection of disabled vehicles with driver warnings in blind curve areas. Test results showed impressive results in improving safety. For instance, in a comparison of maximum deceleration for avoiding a collision with a stopped vehicle on a blind curve, maximum deceleration without the warning was 4.8 m/s 2, whereas it was 3.6 m/s 2 with the warning, showing that braking could be less urgent with the warning.
Systems to detect stopped vehicles, slow vehicles, and congestion were developed based on visible image processing, infrared image processing, and millimeter-wave radar. Tests conducted on the Tomei Expressway and the Oita Expressway verified the basic performance of the sensors.
Road Surface Condition Alerts In the ideal case,...
