Truck Monitoring and Warning Systems for Freeway-to-Freeway Connections: Summary

1999PDFResearch PaperLee, Clyde E.Borchardt, Darrell W.Fei, QiyueUniversity of Texas at Austin. Center for Transportation ResearchTexas Transportation InstituteTexas. Dept. of Transportation. Research and Technology Transfer SectionUniversity of Texas at Austin. Center for Transportation ResearchUnited StatesTexasTrucksRamps (Interchanges)InterchangesFreewaysSpeedWarning systemsMonitoringInfrared detectorsSoftwareData collectionInformation processingBefore and after studiesWarning signalsFlashing traffic signalsRollover crashesInfrared sensorsTX/00-2915-S7-2915-SProject summary report (9/98-8/99)This project focuses on the development and evaluation of a truck monitoring and warning (TM&W) system for detecting high, long, fast trucks at freeway-to-freeway connections and activating displays to warn the truck drivers of potential hazards as their vehicles approach the curved section of an interchange ramp. The basic study was conducted on the elevated left-turn ramp for traffic moving from southbound on the I-610 loop freeway to eastbound on SH 225 (LaPorte Freeway) in Houston, Texas. The TM&W system used three infrared light-beam sensors with a special microcontroller-based signal processor, named TDA3 (Traffic Data Acquisition), to determine the speed, length at 7 ft (2.1 m) above the road surface, and arrival time for every vehicle that blocked the light beams. When selected criteria were met, the TDA system sent a warning message to the driver. Software for data collection and processing was developed, and before-and-after speed-change studies were conducted to determine the effect of applying the TM&W system at the curved, elevated interchange ramp. The results of this research indicate that activating flashing-yellow-light warning displays for only the trucks exceeding the preset criteria caused an average additional 2 mi/h (3.2 km/h) speed reduction beyond normal, before the trucks entered the curved portion of the ramp. Recommendations are made for improving the warning message's impact on drivers and for implementing the TM&W system on a statewide basis.95