The only sign of trouble aboard a Norfolk Southern train hauling roughly 9,000 tons of Canadian crude in western Pennsylvania last year was a moderate sway in the locomotive as it entered a bend on the Kiskiminetas River.
The first 66 cars had passed safely around the curve when the emergency brakes suddenly engaged, slamming the train to a stop. The conductor trudged back nearly a mile through newly fallen snow to see what had happened.
Twenty-one cars had derailed, one going through the wall of a factory. Four tank cars were punctured, sending 4,300 gallons of crude pouring out of the wreckage.
The cause of the accident in North Vandergrift was identified as a failure in the rails -- not aging or poorly maintained tracks, but a relatively new section laid less than a year earlier.
The February 2014 crash fits into an alarming pattern across North America that helps explain the significant rise of derailments involving oil-hauling trains over the last three years, even as railroads are investing billions of dollars in improving the safety of their networks. A review of 31 crashes that have occurred on oil trains since 2013 puts track failure at the heart of the growing safety problem.
Track problems were blamed in 59 percent of the crashes, more than double the overall rate for freight-train accidents, according to a Los Angeles Times analysis of accident reports. Investigators and rail-safety experts are looking at how the weight and movements of oil trains may be causing higher-than-expected track failures.
The growing number of trains hauling crude oil from Canada and the Northern Plains are among the heaviest on the rails today, many extending more than 100 cars in length and weighing 19,000 tons or more.
Not since the early days of John D. Rockefeller's oil trust have railroads played such a central role in moving oil from wells to refineries. Oil shipments by rail have soared -- an eighteenfold increase between 2010 and 2014 -- as domestic oil production has escalated faster than the construction of new pipelines to carry it to market.
Concerns about the safety of hauling crude began to rise after the horrific Lac-Megantic accident in Quebec, Canada, in July 2013, which left 47 people dead and the city's downtown in ruins.
The Federal Railroad Administration is preparing to issue in coming weeks a new set of initiatives to address the track problems, after previously clamping tighter restrictions on tank-car designs and railroad operations. But solving the track problems could be a formidable challenge.
The crashes have occurred as the nation's railroad system is being asked to do more than at any time in history, putting additional wear and tear on the tracks. Since 2001, railroads have seen a modest 12 percent increase in the number of cars they haul, but a 24 percent jump in the more comprehensive measurement of cargo that looks at the weight and train mileage the system has to bear, known as ton-miles, according to industry data.
Though railroads have significantly improved safety in general, the oil-train accidents are a worrisome trend in the opposite direction and not fully understood.
Of the 31 crashes involving crude or ethanol since 2013, 17 were related to track problems and 12 a mix of other causes. The cause of the two other crashes remains unclear. The count is based on final or preliminary government and railroad investigations that were collected by the Times under the Freedom of Information Act or in U.S., Canadian and railroad company filings.
Weight, oil sloshing and cold temperatures are among the issues that might be exacerbating the problem, according to rail-safety experts.
Investigators at Safety Transportation Board Canada, which is examining the eight accidents that have occurred in that country, are beginning to suspect that the oil trains are causing unusual track damage.
A Section on 10/12/2015