Project level highway management framework

Abstract

Saskatchewan Highways and Transportation (SHT) is responsible for 26,125 km of highways in the province. The highway system is divided into primary and secondary highways. The primary highway system provides an inter-regional, inter-provincial, and inter-national highway network that was built to accommodate traffic volumes in excess of 4,000 vehicles per day with significant numbers of heavily loaded trucks. The secondary highway system consists of structural, thin membrane surface (TMS), and gravel highways. TMS highways were constructed to provide feeder links into the primary system for relatively low volumes of traffic with few heavily loaded trucks.

Years of increasing volumes of heavy trucks and inadequate funding on the TMS highway system have forced SHT to evaluate various management strategies. New maintenance and management strategies like partnerships with Rural Municipalities and full depth in-place chemical strengthening have been developed and, along with conventional management strategies, are being used throughout Saskatchewan.

The purpose of this research is to develop a project level analytical framework capable of evaluating management strategies for secondary highways, based on SHT surfacing and structure standards. The best management strategy is the lowest total cost strategy (agency and road user) based on SHT standards. Probabilistic modeling was also included in the framework so uncertainty in the variables, like length of the service life of these new strategies, could be analyzed.

A project on Highway No. 19 was evaluated to demonstrate the framework. From the analysis, the full depth in-place chemical strengthening was the preferred strategy if it lasted 15 to 20 years, relative to a 15 year expected life of the conventional strategy. As well, as the technology advances in Saskatchewan, it appears that the full depth in-place chemical strengthening should decrease in cost while the conventional strategy increases in cost as aggregate sources are depleted. This trend should result in long-term cost savings to SHT.