Benefit

In Colorado, a down hill truck speed warning system installed on I-70 reduced runaway ramp usage by 24 percent and contributed to a 13 percent drop in crashes involving trucks and excessive speeds.


May 1997
Glenwood Canyon, Interstate 70,Colorado,United States


Summary Information

In the 1980s the Washington DC area experienced several accidents involving truck rollover accidents at entry and exit ramps on the Capital Beltway . As a result, two major interchanges and one exit ramp were selected as test sites for deployment of ramp rollover warning systems. The systems were designed to alert truck drivers to slow down when maximum safe speeds were exceeded as they approached curved entry/exit ramps. Before the systems were implemented, there were six reported rollover truck accidents at the Maryland site from 1985 to 1990 (I-495E/I-95N), and two reported accidents at each of the Virginia sites from 1986 to 1989 (I-495W/I-95S, and I-495W/ Route 123N). During the post deployment evaluation period (1993-1997) no rollover accidents occurred at any of these sites. In addition, data collected from all three sites indicated that trucks who activated the warning sign had an average speed reduction of 8.3 miles per hour (mi/h), and trucks that did not activate the warning sign had an average speed reduction of 6.5 mi/h as they approached the ramps.

In Colorado, a down grade warning system integrated a weigh-in-motion (WIM) system with a dynamic message sign (DMS) system to advise drivers of safe descent speeds as they approached a steep negative grade on a mountain freeway (I-70). The system was evaluated and the analysis indicated the system decreased truck use of runaway ramps by 24 percent. In addition, there was a 13 percent drop in accidents involving excessive truck speeds.

Notes:
See also:

Strickland, Rodney R. and Hugh W. McGee. "Evaluation Results of Three Prototype Automatic Truck Rollover Warning Systems." 77th Annual meeting of Transportation Research Board, Washington, DC. January 11-15, 1998.

"IRD Uses WIM Info In Suite of Truck Safety Advisory Systems." Inside ITS. December 15, 1997.

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Source

Words of Warning

Author: Taylor, B. and A. Bergan

Published By: ITS: Intelligent Transport Systems

Source Date: May 1997

Other Reference Number: Issue No. 10


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Benefit ID: 2000-00079