New instrument for tracking rail failures

Repost from

One Solution To Ending Train Derailments

Wed, 01/22/2014
Joel Hans, Managing Editor,

Amid a few newsworthy derailments of trains carrying crude oil, energy companies and the public alike are concerned about the future of the U.S. rail infrastructure and what can be done in the near future to mitigate potentially serious and deadly incidents. With some 140,000 route-miles of track in the U.S. as of 2011, and thousands of bridges spanning rivers or interstates that must be navigated on a daily basis, there are countless points of failure.

Civil engineers have long been aware of the way that seasonal heating and cooling can affect the very structure of the railroad ties via expansion and contraction, particularly near bridges. To mitigate those affects, engineers have been using expansion joints on bridges, but when it comes to the extreme heat that much of the continental U.S. sees on an annual basis, it’s difficult to engineer a system that can withstand as much as four feet of expansion in a mile-long section of rail.

When this happens, the rail can buckle, a phenomenon known in the industry as a “sun kink,” which are leading causes of train derailments. In the winter, extreme bouts of cold can cause enough contraction to crack ties and pull them apart, to the point where they need to be warmed by up using flaming rope or other methods.

Naturally, the companies that manufacture steel tracks are doing more work to pre-stress rails and joints to minimize these affects. But one company, Alliance Sensors Group, argues that while many engineers within railway companies and mass transit agencies are doing good work to instrument bridges for movement, structural problems or track shifting, many of these inspections are visually-based, and not often enough, which leaves routes open to unnoticed flaws.

Instead, the bridges can be instrumented to determine if there are any flaws in the tracks, which means that railway companies could divert trains and repair the issues before an incident, such as a derailment, takes place.

Alliance Sensors Group has developed a linear sensor that can measure bridge movements and create empirical data on the condition of rails and bridges that can be tracked in real-time. They’re able to survive all the elements that leave railways buckling or cracking, such as extreme cold and heat, along with humidity, rain and snow. An IP67 rating guarantees that it won’t succumb to the elements.

In the photo, the company’s LV-45s have been affixed to the pier and to the bridge using ball joint swivel rodends. With this in place, the system can measure positional changes in three axes and track those changes over time, which means engineers can proactively identify potential problems, or, in the worst case, respond faster to potential derailment incidents. And if that means less trains coming off the tracks, we’re completely onboard.