TRANSPORTATION -- July 7, 2010 at 6:27 PM ET
Heat Wave Causes Kinks in Rail Tracks
The Massacusetts Bay Transportation Authority has had to repair so-called "heat kinks" during recent high temperatures.
The triple-digit temperatures pummeling the East Coast this week present many dangers: heatstroke, dehydration and power outages. This week, the Washington, D.C., Metro system announced that it's keeping close tabs on yet another heat-related threat: the warping of rail tracks.
During multiple days of extreme heat, the temperature of steel tracks can rise sharply, causing them to expand into wavelike shapes known as "heat kinks." Sometimes, the tracks expand so far out of their normal gauge that cross ties and ballasts, which normally shore up the rail and provide structural support, can no longer do their job.
Worst case scenario, "the train can't negotiate these large kinks in the rail, and they derail," says Andrew Kish, owner of a rail technology consulting firm. "The track becomes unstable and buckles out."
One so-called "heat kink" appeared on the Washington, D.C., Metro's red line early this week. It slowed travel for some passengers, but was caught early and posed no safety problem. The enlarged section of the rail was removed and replaced.
Officials at the Washington Metropolitan Area Transit Authority assure that they have the situation under control. Train inspectors have checked every track on every Metro line, says Steven Taubenkibel, a WMATA spokesperson. "What we're simply doing is we've encouraged the train operators to monitor the rails to make sure nothing seems unusual." A heat kink was also replaced late Monday night on the Massachusetts Bay Transportation Authority's orange line. Maryland's MARC train, Philadelphia's SEPTA system and the Virginia Railway Express also experienced heat-related delays.
Already the July heat wave has broken multiple records in cities along the eastern seaboard, including Philadelphia, Baltimore, Richmond, Washington, D.C., and Frederick, Md., which reached a record 105 degrees.
The heat wave is caused by a strong system of air pressure across the East Coast, says Russ Schumacker, a meteorologist and assistant professor of atmospheric sciences at Texas A&M University: "There's an unusually strong ridge of high pressure, which causes sinking air and keeps the clouds away."
Adds John Hom, a U.S. Forest Service scientist, many urban areas lack the trees that cool temperatures in suburban areas. The lack of photosynthesis, which provides cooling elsewhere, creates a "heat island" effect in cities that worsens the heat. "Almost all large cities - Philadelphia, New York City, D.C. - have almost no vegetation," Hom says. "That's going to create a loss of mixing of cool air... And land surface temperature increases when there's less vegetation, such as urban tree canopies."
More deaths have been caused by heat than by tornadoes, hurricanes, floods and lightning combined, making it the number one weather-related cause of death, according to the National Oceanic and Atmospheric Association. More than 1,500 people are believed to die each year from excessive heat.