In the wake of two serious passenger-train derailments, the nation's railroads plan to review the way they operate in extremely hot weather, which can buckle tracks.
The study, to be coordinated by the Association of American Railroads, would look at the policies and procedures rail companies use for running trains and maintaining track in searing temperatures.
"Essentially, this will look at best practices for dealing with those [heat] issues," association spokesman Tom White said Tuesday. "It's an attempt to be proactive on this."
The decision follows the Monday derailment of an Amtrak train in Maryland that injured more than 100 people.
It comes three months after the Amtrak Auto Train bound from Sanford to Washington tumbled off the tracks in Crescent City, killing four passengers and injuring more than 100.
In both cases, engineers reported that the track buckled just before the trains crashed. Buckles, called "sun kinks," form when long stretches of welded rail become superheated by the sun.
Preventing sun kinks As the steel expands, forces in the rail increase until it buckles or bows out -- sometimes up to 1 foot. Often, it happens as a train is bearing down, adding to the force already in the rail.
All railroads have procedures for preventing sun kinks, and their number has fallen sharply during the past 25 years.
In the 1980s, sun kinks routinely caused about 100 derailments a year, according to the Federal Rail Administration.
In the 1990s, they caused about 35 annually. Last year, there were 44.
Despite the success, preventing sun kinks is as much an art as a science. That's because there's no reliable way for maintenance crews to measure the force inside a rail, said Andrew Kish, one of the nation's leading researchers on continuous welded rail.
Typically, crews place a magnetic thermometer on the rail and use its outer temperature as a stand-in for force inside the rail.
But Kish said the reading has no relationship -- "none whatsoever" -- to the true force the steel may be under.
"There's a huge concern in the industry," said Kish, who does research for the U.S. Department of Transportation. "It's a very difficult, very complicated problem."
New 'heat orders' In addition to trying to prevent sun kinks through good maintenance, railroads also slow trains down when they think conditions may be ripe for kinks to form.
Tuesday, CSX Transportation, which maintains the section of track involved in Monday's derailment, issued a new policy on so-called "heat orders."
When heat orders are in effect -- a decision made on a case-by-case basis by local rail teams -- passenger trains will have to slow to the speed approved for freight trains, which varies depending on track conditions.
Normally, passenger trains would simply have to slow by 10 mph.
CSX spokesman Adam Hollingsworth said the decision was prompted by the two recent derailments.
"It's an abundance of caution," he said.
It has been a rough three months for CSX. The Florida derailment in April resurrected questions about the company's maintenance work -- work that, in the past, had been repeatedly criticized by federal inspectors.
Records show the curve where the derailment took place was a chronic problem for the railroad.
It tried several times to shore up the rail bed in that area, but it kept deteriorating.
Derailments 'eerily similar' To make matters worse, federal investigators have said that CSX, in its effort to fix the curve, may have failed to take steps critical to preventing sun kinks. A final report on the Crescent City wreck isn't expected until this fall, but CSX is already being sued.
The Maryland crash will only draw more attention to the Crescent City report because the two derailments are "eerily similar," said a spokesman for the National Transportation Safety Board.
Both involved an Amtrak train racing off CSX tracks. Both occurred at speeds of about 60 mph. Both happened after freight trains had passed through without a problem, and both involved stretches of welded rail that had been in the sun all day.
Despite those similarities, NTSB spokesman Greg Martin said generally his agency has not handled many derailments that were ultimately blamed on sun kinks.
"There's no indication of a trend in the last few years," Martin said. "We just haven't seen that."
Jim Stratton can be reachedat email@example.com 407-420-5379.