Aspects of performance of truck weigh stations

Abstract

The performance characteristics of truck weigh stations are presented. Seasonally operated scales and random inspection sites are found to be at least 3 and 8 times respectively as effective in detecting violations as continuously operated permanent scales with no alternative bypass routes. The availability of alternative bypass routes reduces truckers' perceived probability of detection at permanent weigh scales by at least 5%. Higher perceived probabilities are associated with high inspection rates.Queuing theory is employed to study the impact of two alternative manpower levels on the performance of con tinuously operated permanent weigh scales. For the level of truck traffic volume considered, it is found that, theoretically, there is no significant delay to truck traffic through such weigh scale stations irrespective of the manning strategy. It is concluded that it is feasible to maintain minimal staff at the scales and redirect human resources to increase inspection capacities of other methods.The queuing model for the permanent scale operations represents a rare practical example of a classic M/Ek/1 model where the k stages in the service time Erlang distribution are real and not necessarily imaginary. Key words: permanent scale, effectiveness, enforcement, violation, inspection, arrival time, service time.