Commercial Vehicle Loading in an Urban Environment

Increasing commercial vehicle operations on highways is resulting in increased structural depreciation of our road infrastructure assets. This increase in commercial trucking is also increasing truck loading on urban pavements. By actively monitoring and quantifying commercial truck loadings and reducing the amount of overloading, it may be possible to better design and extend the life of road and bridge structures. Many State and Provincial transportation departments have extensive traffic data collection and commercial vehicle enforcement programs in place. Urban municipalities have typically not implemented programs of this type to a comparable level and therefore have not realized the benefits of these programs. However, commercial traffic flow is often more concentrated and may include stop and go conditions. Therefore commercial vehicles in an urban environment can significantly increase the damage inflicted onto urban roads compared to rural roads. This paper presents the pilot implementation of a weigh in motion (WIM) and video surveillance system installed in Saskatoon, SK. Specifically this paper presents commercial vehicle loading data collected in an urban environment, quantifies overloading that is occurring, the effects this overloading is having on the roadway infrastructure, and what can be done to reduce the overloading. Using data from a recently installed WIM system with video capture capabilities commercial vehicle traffic types and volumes were quantified with regards to time of day, day of week, percent trucks overloaded, and severity of overloading. The use of the WIM system as a tool for enhancing traffic data collection and commercial vehicle enforcement in an urban environment is examined. The analysis showed that for the study period, 2.2 percent of commercial vehicles exceeded the allowable gross vehicle weight and 12.8 percent of commercial vehicles exceeded one or more of the axle, axle group, and gross vehicle weight limits. Overloading was most common on weekdays and during the working day. The types of vehicles most likely to be in violation of weight limits were the seven and eight axle combination units. However, when roadway loading due to excess weight was considered, the greatest contribution to excess loading came from the class with two and three axle trucks. These are typically local service vehicles that operate within the vicinity of the city and are generally not subjected to inspection at fixed weigh stations to the same level as larger trucks used for long-haul operations.