Final Research Findings on Traffic-Load Forecasting Using Weigh-in-Motion Data

00762940405729271998Research Report (9/96-8/97)PDFTech ReportTX-98/987-77-987Weigh in motionRehabilitation (Maintenance)Traffic dataTraffic loadsAxle loadsForecastingLong range planningTraffic countsFrequency distributionsTrucksTractor trailer combinationsLane useLufkin districtPatternsPavement damageTraffic reportsTrendsUS 59TexasUnited StatesUniversity of Texas at Austin. Center for Transportation ResearchLee, Clyde E.Souny-Slitine, NabilUniversity of Texas at Austin. Center for Transportation ResearchTexas. Dept. of TransportationBTS Data DirectoryThe overall objective of Project 7-987 was to develop a long-range pavement rehabilitation plan for a segment of US 59, a four-lane divided principal arterial highway in TxDOT's Lufkin District. To identify feasible pavement structures, test sections that would utilize most efficiently the existing pavements and materials were constructed in the southbound lanes near Corrigan, Texas. To quantify traffic loads on the test pavements, two weigh-in-motion (WIM) systems were installed: one two-lane system adjacent to the five rigid-pavement test sections located 8 km north of Corrigan, and the other adjacent to the five flexible-pavement test sections about 3 km south of Corrigan. These WIM stations were operated virtually continuously from 1993 through 1997 to record data about the date, time, speed, lane of travel, wheel loads, number of axles, and axle spacing of every southbound vehicle (about 7,500 per day) that crossed the sensors in each lane. In addition, special sensors were operated to collect sample data concerning the air and pavement temperature and the lateral position of the vehicle tires (single or dual) within each traffic lane. The result was an exceptionally comprehensive traffic data set. This final project traffic report complements and extends the time frame (to 5 years) of the traffic data analyses presented previously in Research Reports 987-5, -6, and -8. The traffic data analysis included exploration of patterns and trends in vehicle counts, lane use, and axle load frequency distributions by axle type, location on the vehicle, and vehicle class. The results indicated that on average during the 5 years, trucks accounted for about 28 percent of all southbound vehicles, and that five-axle tractor semitrailer trucks comprised about 62 percent of all trucks. Generally, 74 percent of the vehicles, and 82 percent of the trucks, traveled in the right-hand, southbound lane. The overall southbound vehicle count grew at an annual rate of approximately 2.5 percent, while five-axle tractor semitrailer trucks, the dominant truck class, increased in number about 6 percent each year. This suggests that traffic load forecasts should consider separately the respective growth rate for each vehicle class (by axle arrangement and axle-load frequency distribution) as the axles on each vehicle class cause different often disproportionate amounts of pavement damage.85