Technical and Economic Feasibility Study of At-Grade Concrete Slab Track for Urban Rail Transit Systems

DOT-TSC-1765
The report presents work conducted to evaluate the technical and economic feasibility of using concrete slab track systems for at-grade transit track. The functions of a rail transit track system are to guide railway vehicles and provide a safe and acceptable ride to passengers. Traditionally, a track system with cross ties and ballast has been used for at-grade construction. Such track systems utilize wood, monoblock concrete, or two-block concrete ties. These track systems undergo permanent deformation during loading due principally to consolidation and degradation of ballast that occurs during track life. Therefore, maintenance operations are required periodically to provide proper surface and alignment. Improved track systems with superior capabilities to those of conventional track provide possible solutions to problems of continuing and costly track maintenance. A slab track system consisting of a continuous concrete support, sub-base, and compacted subgrade, is one example of such improved track system. Rails are secured to the concrete support using fasteners that provide restraint to rail movements and therefore, ensure proper gage and alignment. Experience with concrete slab track systems in foreign countries has shown that such track systems result in decreased maintenance and increased reliability of service. This experience has also indicated a generally higher initial cost of slab track. This report presents a world-wide review of details and performance of slab track projects and compares features of slab track systems with those of conventional ballasted track. Methods of constructing slab track systems and a cost comparison between slab and ballasted track systems are discussed. Recommendations for future research efforts related to the development of at-grade concrete slab track systems are also presented.