Research Gets the Kinks Out of Railroad Track 9/24/2002
From: Bruce McIntosh of the Portland Cement Association, 847-972-9162, bmcintosh@cement.org; or Claire Ball of the Construction Technology Laboratories, 847-972-3222, cball@CTLGroup.com SKOKIE, Ill., Sept. 24 -- The use of track connected to a concrete slab instead of traditional ties and ballast promises to prevent transit and rail track from buckling in hot weather, according to research by the Portland Cement Association, a trade group based in Skokie, Ill. When the track heats up, expansion causes it to buckle. The phenomenon, known as sun kink or heat kink, may have caused the July 30 Amtrak derailment in Maryland that injured 97 people. Heat-related speed restrictions also slowed service last summer. Winter brings its own temperature-related problems. In cold weather, contraction causes welds in the track to pull apart, creating a safety and maintenance concern. PCA is sponsoring a multi-year research project at Construction Technology Laboratories, Inc., to develop track requiring no ballast. Among many potential benefits is safer track capable of accommodating heavy-loaded freight cars and high-speed passenger trains. Most importantly, the track would be stable enough to resist buckling during hot weather and pulling apart during cold snaps. Called "slab track," the system is widely used in Europe and Japan. The first stage of the study was recently completed. A full-size concrete slab (similar to a highway pavement) with rails and fasteners was constructed in the laboratory and subjected to 3 million cycles of simulated train loading. These tests simulate 315,000-pound freight cars, the largest cars in use today. Following these tests, engineers hope to test the concrete track at the federal government's high-tonnage loop in Pueblo, Colo. There, fully loaded 70-car trains will operate over the track for two years. These tests will evaluate the long-term performance of concrete slab track. The data gathered from this work will establish design precedents for future slab track installations and improve our knowledge about how a concrete slab instead of traditional ties and ballast track can resist the destructive forces of heavy loads, speed, and nature. Based in Skokie, Ill., the Portland Cement Association conducts market development, research, and education on behalf of its members, cement companies in the United States and Canada. A for-profit subsidiary of PCA, Construction Technology Laboratories, Inc., conducts research, consulting, engineering, and materials testing for the construction and transportation industries. Media contacts: At the Portland Cement Association, Bruce McIntosh (847-972-9162; bmcintosh@cement.org). At Construction Technology Laboratories, Claire Ball (847-972-3222; cball@CTLGroup.com). High-resolution images of the laboratory tests are available at http://www.cement.org/tr/tr_news.asp |