Acquiring Traffic Data by In-Motion Weighing

The need for quantitative information about highway vehicle weights has historically been fulfilled through static weighing operations. An electronic weighing system referred to as weigh-in-motion (WIM) has been developed which obtains wheel weights, axle spacing, and speed of vehicles operating in a normal traffic stream. The accuracy of the WIM system has been evaluated in a statistically designed field experiment. The experiment consisted of comparing wheel weights measured by wheel-load weighers, platform scales, and the in-motion weighing system. The experiment utilized a variety of vehicles representing several different vehicular classes and a number of different vehicular loads. The possible effects of vehicular speed and pavement profile were also examined. The study indicates that the in-motion weighing technique can provide adequate static weight, speed, and classification data for traffic survey purposes without the need for specially constructed weighing sites. All hazards to traffic and survey personnel would be eliminated without any delay and expense to the road user.