NTSB Press Release

National Transportation Safety Board
Office of Public Affairs


May 1, 2001

WASHINGTON, D.C. - The National Transportation Safety Board today recommended that the Department of Transportation complete rulemaking on adaptive cruise control and collision warning system performance standards and require collision warning systems on new commercial vehicles.

The recommendation was part of a Safety Board special investigation on highway rear-end collision prevention technologies conducted over the last 2 years. Information was compiled from nine rear-end collision accident investigations and a public hearing on Advanced Safety Technologies held in Nashville, Tennessee from August 31 to September 1, 1999.

A common factor in all nine accidents examined for the report was the rear vehicle driver's inability to see or accurately determine traffic conditions ahead. Smoke, sun glare, fog, distraction, and fatigue were some of the factors obstructing the drivers' view and preventing them from reacting earlier to slowed or stopped traffic.

The report examined two forms of Intelligent Transportation Systems (ITS) designed to alert drivers and prevent rear-end collisions; adaptive cruise control and collision warning systems. The adaptive cruise control detects slower moving vehicles ahead and automatically slows the vehicle, by up to 25%, to a comparable speed. Collision warning systems detects slower moving traffic ahead and alerts the driver. According to a 1992 Daimler-Benz study, if passenger car drivers have 0.5 second additional warning time, about 60 percent of rear-end collisions can be prevented.

While the Board recommended requiring collision warning systems on new commercial vehicles, it also recommended that the DOT determine performance standards for adaptive cruise control and collision warning systems for new passenger vehicles.

In additional recommendations, the report asked the National Highway Traffic Safety Administration, the Federal Highway Administration, the Intelligent Transportation Society of America, and truck and bus manufacturers to inform the public, and commercial drivers of the benefits, use and effectiveness of the systems. The Board also recommended truck and bus manufacturers provide training to commercial vehicle drivers using adaptive cruise control or collision warning systems.

The complete report, Special Investigation Report on Highway Rear-End Collision Prevention Technologies, will be available on the NTSB's website in several weeks. In the interim an abstract containing a complete listing of the report's conclusions and recommendations is available on our website's "News and Events" page. Printed copies of the report may be purchased later this spring from the National Technical Information Service (NTIS) (800) 553-NTIS.

NTSB Office of Public Affairs: (202) 314-6100



The National Transportation Safety Board (NTSB) is an independent federal agency charged with determining the probable cause
of transportation accidents, promoting transportation safety, and assisting victims of transportation accidents and their families.