Concrete Slab Track State of the Practice

Abstract

Railway track technology has evolved over a period of 150 years since the first railroad track on timber ties was introduced. For much of this period, the conventional track system, commonly referred to as the ballasted track system, has consisted of certain components including rails, ties, ballast, and the subgrade (roadbed). Over the last 20 years, there has been an increase in the use of concrete slab technology for transit, commuter, and high-speed train applications. Essentially, a slab track consists of a concrete slab placed on a subbase over a prepared subgrade. The rails may be directly fastened to the concrete slab, or the rails may be placed on concrete blocks or another slab system that is placed on (or embedded in) the underlying concrete slab. A version of the slab track, developed in the Netherlands, incorporates rails embedded in a trough in the slab and surrounded by elastomeric material. The slab track systems for passenger service applications incorporate several requirements to mitigate noise and vibration. The slab track system for transit applications in the United States and for high-speed rail in Europe and Japan has performed well over the last 20 years. Also, the limited application of the slab track system for mixed passenger service-freight operations has also exhibited good performance. Because of the continued increase in gross tonnage expected to be carried by railroads and the expected growth in high-speed passenger rail corridors, with the smaller deviation in the rail geometry allowed for high-speed rail, the need for a stronger track structure is apparent. At-grade concrete slab track technology is expected to fill the need for stronger track in the United States. The state of the practice related to concrete slab track technology is summarized.