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http://www.kentucky.com/mld/kentucky/news/9120979.htm

This is a link to an updated news report about the loaded coal train that derailed in Southern Illinois this morning.

snip:
>>Thomson said the train of three locomotives and 136 cars loaded with coal derailed as it crossed a bridge over the roadway. He said eight coal cars fell onto the interstate and four others derailed, but those did not fall onto the roadway.

It's unclear whether the bridge over the interstate gave way or the train simply derailed when it was on the bridge, he said.

Tom Zerrusen, a district engineer with the Illinois Department of Transportation, told the St. Louis Post-Dispatch that the bridge seemed stable, even though a concrete walkway alongside the track crumbled when the train cars fell.

"There is no problem with the overhead bridge," Zerrusen said. "People can use the road as soon as we can get the coal removed."

Fleda McCoy, 46, of Murphysboro, had just merged onto the interstate going south when she saw the train derail.

She said she saw debris falling from underneath the bridge before the train cars fell off.

"It seemed like the track was giving away," McCoy told The Associated Press in a telephone interview. "Fragments and pieces of coal started hitting my car."

She said her car wasn't damaged, but she was shaken, having stopped only two car lengths back from the derailment.<<

Wouldn't a railway bridge that crosses a major interstate be subjected to very strict inspections of the bridges on a regular basis? Shouldn't there have been some early warning signs that the bridge was becoming unstable?

For some reason, this incident seems hinky to me.

Coal cars and rail safety are the core of my current work. The railroad companies have a small number of specialized cars that run down the tracks to look for defects. The instruments on the cars can examine up to 500 miles of rail each day. That means that the whole rail system gets a "fly-by" inspection ONCE each year.

There are also research and development sites that can examine a train moving by at 55 MPH. The laser scanners can measure all the face and flange angles on every wheel. There are strain gauges in the track to detect lateral pressure indicative of a wheel set that is too wide, thus forcing the rails apart inappropriately. The vertical strain gauges can detect impacts hard enough to break the welds between two pieces of rail. These instruments are not widely deployed because they are still in development.

My hardware includes vertical accelerometers on each bearing, thermo-couples on the inner and outer races and a tri-axial accelerometer on the "sill" at each end of the car. I can detect 55 types of bearing defects from the vertical accelerometer using digital signal processing of a 50 KHz sample over 20 seconds. That sample is performed on each bearing daily. Temperatures are monitored to look for hot bearing or assymmetric wear. I can reliably detect a hot bearing 100% of the time. The infrared "hotbox" sensors deployed every 20 miles on the tracks have an 80% false rate of report for hot bearing.

The tri-axial accelerometers measure lateral "hunting" motion that can detect an imminent "jump" off the track. The vertical channel detects vertical jarring to the payload on the car. It can also detect a derailed wheel that is bouncing over the ties, but hasn't left the track bed yet. The longitudinal channel records the "slam" from pulling the slack out of the track or putting the brakes on. That "slam" will knock you right off your feet in the caboose.

My instruments also include a GPS to record the time and location of an observed defect. If all cars show a similar problem over a section of geography, we can infer a track problem. The data is reported remotely over a Verizon Wireless 1XRTT link to the internet. All this stuff consumes electrical power, thus we put a Timken generator bearing aboard one of the wheels to keep the battery charged.

This stuff is all in the R&D stages now. I'm improving the power management with a PIC microcontroller to preserve the battery life. New hardware this year will allow me to sample all 4 bearings on a single truck at 50,000 samples per second concurrently. That will permit detection of vibrations coupled through the axles on a wheel set and through the truck frames between wheel sets.

My cars also have an 802.11b wireless network that feeds status and alerts to the locomotive engineer. I can provide a reliable warning to the engineer and permit time to stop the train before an accident occurs.

The rail industry is still very perplexed about the cause of wheel damage. The railroad operators get blamed for having bad track. The car owners get blamed for poor wheel maintenance. In the end, the car owners just keep replacing bad wheel sets while trying to figure out why the problem is occurring. I'm hoping my onboard instruments will provide them a clue soon.