FERIC conducted a field study to determine the optimum aggregate thickness for roads traveled primarily by trucks equipped with tire pressure control systems (TPCS). The main objective was to establish if savings during road construction could help justify the cost of TPCS technology. The initial results showed that aggregate thickness could potentially be reduced by more than 28% at the test location. This reduction would result in savings in aggregate costs of at least $4000/km, which could help cover the cost of TPCS.
Structural design catalogues enable road builders and field personnel to optimize aggregate thickness based on field conditions, thereby reducing overall road construction costs, increasing road performance, and reducing maintenance costs. Catalogue users can select a design suitable for a given level of road performance and traffic as well as for various subgrade and aggregate properties.
For optimal performance, a road’s wearing course (“running surface”) should use suitable aggregates. FERIC reviewed the characteristics of the wearing course material used by several member companies in eastern Canada and compared the results with company specifications and those of roads authorities. Most aggregates failed to meet either type of specification. The report describes the characteristics of aggregates suitable for use in a wearing course, and recommends how to improve road performance through proper specification of aggregates.