In a preliminary study, researchers placed two laser units at the bottom of an entrance ramp, one at axle level to detect speed, the other at the height of a truck cab to detect that it was a truck and not a smaller vehicle. If the truck was speeding, yellow lights flashed to warn the driver he was going too fast. The system was tested on a ramp at Texas 225 and Loop 610 in Houston.
In the test, violators did slow their speed when they saw the lights flashing, said Sally Wegmann, transportation operations director for the Texas Department of Transportation.
Researchers from Texas A&M University and the University of Texas are studying traffic patterns and fatality rates for Houston's major interchanges. Several laser units and light panels could be installed in the next few months. Possible intersections include U.S. 59 at Loop 610 and Interstate 45 and Loop 610.
Bill Webb, president of the Texas Motor Transportation Assn., notes that significant banking and curves on interchanges can cause a rollover - and at some Houston interchanges, even 5 or 10 mph over the speed limit can trigger it.