In an effort to reduce the number of rear-end collisions on America's highways, the National Transportation Safety Board (NTSB) is recommending the U.S. Department of Transportation (DOT) require the standardization and implementation of collision prevention technologies on all newly manufactured commercial vehicles. The NTSB also made recommendations to the National Highway Traffic Safety Administration, the Federal Highway Administration, the Intelligent Transportation Society of America and motorcoach manufacturers, urging them to develop and implement a program to inform commercial drivers of the benefits, use and effectiveness of collision prevention technologies. The recommendations stem from a two-year special investigation conducted by the NTSB that revealed a disturbing trend in car crashes. According to the NTSB, of the more than 6 million car crashes that occurred on American highways in 1999, approximately 1.8 million were rear-end collisions. While commercial vehicles made up only 3% of vehicles on the road, they were involved in 40% of fatal rear-end collisions. According to the government's Fatality Analysis Reporting System, 10 motorcoaches were involved in fatal rear-end crashes in 1999. Another finding of the NTSB investigation: because the majority of rear-end collisions are due to a driver's degraded perception of traffic patterns ahead and/or distraction and fatigue, most rear-end collisions can be prevented with mere seconds of warning time. As a result, the NTSB concluded that collision warning devices could help drivers of commercial vehicles avoid rear-end collisions. Lauren Peduzzi of the NTSB said that the motorcoach industry would be well served by the implementation of collision warning devices because they could help ensure safe passage for their riders. In addition, the NTSB recommended that the performance standards of adaptive cruise control (ACC) and collision warning systems (CWS) used in commercial and non-commercial vehicles be standardized by the Federal Motor Carrier Safety Administration to avoid driver confusion. Collision warning devices can take three distinct forms. The first is the ACC, which monitors traffic patterns ahead of the vehicle and applies the engine brake to slow the host vehicle as necessary. The second is the CWS, which sounds a signal to alert drivers of slow or stopped traffic ahead. The final form, the infrastructure-based congestion warning system, uses variable message roadside signs to alert drivers of traffic conditions ahead. Peduzzi estimates that Eaton VORAD Collision Warning Systems currently cost $2,000 to $3,000 per vehicle. Greyhound installed the VORAD collision warning system on 1,500 vehicles in 1991 but abandoned the experiment three years later. Kristin Parsley, manager of external communications at Greyhound, described the devices as ineffective because they raised many false alarms and were distracting to the driver and to the passengers. Since 1994, Greyhound has continued to test collision warning devices on a smaller scale, but has been unable to find a device that overcomes the problems they had with VORAD, said Parsley. However, the NTSB feels that existing technology, combined with appropriate driver training, will be effective in alerting drivers to obstacles ahead, consequently increasing their reaction time and preventing collisions or significantly reducing the severity of impact. The NTSB issued a similar report in 1995 in which it recommended that the DOT sponsor fleet testing of collision warning systems in trucks. Due to inaction on the part of the DOT, however, that recommendation was abandoned.