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Connecting track to a concrete slab instead of laying rail on ties and ballast would prevent track from buckling in hot weather, according to research results released Sept. 24 by Skokie, Ill.-based trade group Portland Cement Association (PCA).


A phenomenon called "sun kink" or "heat kink" — when track temperatures increase and expansion causes buckling — might have contributed to Amtrak's July 30 derailment in Maryland, which injured 97, PCA said.


Cold weather contraction, too, can cause track to pull apart, leading to safety and maintenance concerns.


PCA recently completed the first stage of a multi-year research project at Construction Technology Laboratories Inc. that aims to develop track that wouldn't require ballast or ties.


The association constructed a full-size concrete slab (resembling highway pavement) with rail and fasteners — a system widely used in Europe and Japan — and simulated the effects of 315,000-pound cars completing 3 million loading cycles on the track during various temperatures.


Tests showed that the track was stable enough to resist buckling from the effects of hot and cold temperatures.


PCA plans soon to test the long-term performance of the "slab track" at Association of American Railroad's Transportation Technology Center Inc. in Pueblo, Colo., where 70-car trains would operate over the track for two years.


The association then would attempt to establish slab track design and installation procedures to account for heavy-axle loads, train speed and weather.