Highway Considerations from the Use of Liftable Axles by Heavy Trucks 932989

The provinces of central and eastern Canada have tolerated the use of liftable axles on heavy trucks for many years, and about one quarter to one third of all heavy trucks, a majority of the truck population that hauls the heaviest loads, are so equipped. These trucks have been configured for the most part simply by means of a bridge formula, and their performance as vehicles has been compromised to generate the highest possible gross weight.

This paper presents some theoretical highway impacts of typical heavy trucks that make use of liftable axles and operate in central and eastern Canada. It then outlines some of the practical impacts on pavements observed from weigh-in-motion data. It appears that where liftable axles are widely used, driver behaviour plays a significant role in consumption of the pavement resource, in addition to freight volume. The paper then makes some observations on the care that should be taken by jurisdictions that may be developing truck weight and dimension regulations, particularly if there is to be an increase in allowable gross weight, so that the new regulations guard against the possible highway impacts if liftable axles should be introduced.