A ramp roll-over warning system was installed at three curved exit ramps on the beltway around Washington, DC in 1993. On-site sensors and computers detected truck speeds, weight, and height classification, and then calculated the probability a truck would roll over as it approached. If a truck was at risk, a roadside warning sign was activated to alert drivers to slow down.
At the 3 sites evaluated, historical data indicated there were 6 accidents at the Maryland site from 1985 - 1990, and 2 accidents at each of the Virginia sites from 1986 - 1989. After the system was installed, there were no accidents at any of these sites during the three year post deployment test period evaluated (1993 - 1997).