The province of Saskatchewan has the largest number of public roads per capita in Canada and one of the largest in the world. Over the past decade, pressures on the road network have increased, resulting in accelerated road damage and increased demand to upgrade portions of the highway network. To address transportation infrastructure sustainability issues, Saskatchewan Highways and Transportation (DHT) and Pavement Scientific International, Inc., are researching more cost-effective methods. The research work involves evaluating the technical and economic feasibility of undertaking alternative road construction techniques. A critical component of this research effort is to evaluate the economic feasibility associated with different road construction techniques. The ability to perform whole-life economic analysis associated with long-term infrastructure assets is important to long-term sustainability. By comparing the present value of initial construction and future preservation costs across different road structures and technologies, an accurate assessment of construction and design options is achievable. On the basis of performance predictions and projected structural performance, resource allocation can be optimized more reliably across limited resources and alternative road strengthening systems, providing technically sound solutions that are more economically attractive. With an ability to predict whole life-cycle performance on the basis of future maintenance treatments, road managers can more reliably assess alternative surfacing and structural preservation strategies. The primary focus of this paper is to demonstrate the economic considerations undertaken in evaluating alternative road design and construction methods. This longer-term evaluation approach allows strategic investments in highway infrastructure and allows DHT and other agencies to consider innovative road structural rehabilitation and management strategies more effectively.

Saskatchewan is experiencing significant increases in commercial truck traffic due to grain transportation rationalization, consolidation of the rural grain elevator system, rural economic diversification, and expansion of resource industries. Although increasing truck traffic has longterm implications for the primary pavement system, significant increases hold immediate implications for thin paved roads; many were not originally designed to accommodate heavily loaded commercial trucks. There is a clear need to strengthen many Saskatchewan thin pavements. However, conventional structural strengthening typically involves regrading and granular subbase-base overlay systems, often too expensive because of the cost associated with aggregate hauls and regrading. As a result, the Saskatchewan Department of Highways and Transportation is investigating the use of cold in-place recycling and full-depth cementitious stabilization to strengthen Saskatchewan thin pavements. To this end, industrial waste coproducts such as coal fly ash, bottom ash, and kiln dusts are being investigated as structural cementitious soil stabilizers. The results are presented from preconstruction site investigation methods, laboratory materials characterization, and in situ quality assurance test results. Field performance after 2 years shows cold in-place recycling and cementitious stabilization to be a technically and economically feasible solution for strengthening Saskatchewan thin paved roads built on clay-till subgrades.

The province of Saskatchewan has the highest number of public roads per capita in Canada, totaling approximately 198,700 km. The Saskatchewan Department of Highways and Transportation manages approximately 26,100 km of these public roads. As with most public road agencies, the department has limited resources for managing this relatively large network of low-volume roads and therefore continually strives to research and implement more cost-effective and technically feasible solutions. Of particular concern are approximately 7,500 km of thin membrane surface (TMS) roads that are undergoing accelerated damage as truck traffic and loading increase. Although conventional TMS upgrading strategies are normally effective, there are potentially significant benefits to be gained with implementation of more cost-effective methods of road strengthening. Systems include granular soil strengthening and applications of different cement products, lime, various grades of fly ash, geotextiles, geogrids, natural and manufactured fibers, emulsified bitumen, tall oil, lignin, foamed bitumen, and synthetic ionic and cationic chemicals. Since 1999, in conjunction with Pavement Scientific International and in cooperation with the University of Saskatchewan and product suppliers, the department has constructed pilot projects on Highway No. 19 to identify, develop, and implement more cost-effective strengthening systems. The primary research objective is to investigate alternative road construction systems that will improve the load-carrying capacity and environmental durability of Saskatchewan TMS roads. Improved mechanistic engineering methods played a part in this initiative, and pilot project performance was monitored.

Saskatchewan Department of Highways and Transportation (SDHT) is responsible for maintaining approximately 6500 kilometers of northern gravel surfaced roads. Many of these northern gravel roads are built on poorly graded sand subgrades and may contain protruding bedrock and/or large boulders. Because of this, washboarding, protruding rocks, rutting and potholes are common performance problems of many northern gravel roads. Routine blading of these roads is often ineffective because unstable sand does not maintain its shape and compaction, protruding bedrock and boulders damage motor grader blades, boulders may become dislodged leaving holes in the road, and dislodged boulders are a safety hazard when windrowed along road side-slopes. Clay capping and base stabilization have been used to provide a stable wearing surface, cover protruding bedrock and large boulders, and reduce traffic dust. However, the long-term performance of clay capping and base stabilization can be highly variable and the associated costs can make these conventional solutions untenable. As a result, SDHT investigated the use of in-place rock crushing and stabilization/modification for northern gravel roads with significant proportion of boulders in the grade using a rotomixer/stabilizer. Based on the findings of this study, inplace rock crushing and stabilization/modification is a technically feasible solution for eliminating protruding bedrock and boulders contained near the surface. However, in-place crushing of boulders with unconfined compressive strengths over 50,000 psi resulted in significant damage to the rotomixer mandrel resulting in an approximate cost of just under $13,684 CDN per kilometer. in situ rock crushing with subgrade stabilization and double seal was found to cost approximately $52,017 CDN per kilometer. Berthelot, Gerbrandt, Safronetz, and Sparks.