Some trains inevitably go off the rails — 1,700 of them each year in the United States, an average of five trains per day. Executives at Union Pacific know that the cause of many derailments is wheel failure; 0.025% of the wheels of its coal trains are defective, which seems like an infinitesimal number until you realize that there are 400,000 wheels in use at any given time. A hundred will fail, causing thousands of dollars in damage to trains and to tracks. But which ones? “It’s a needle-in-a-haystack situation,” says Mike Iden, Union Pacific’s director of car and locomotive engineering.
But those needles will soon be easier to find. The 147-year-old rail company has teamed with testing-technology maker Dapco on a robotic, ultrasonic detection machine that can quickly scan all of a train’s wheels for damage. Housed at Union Pacific’s North Platte, Nebraska, rail yard, the system is a special length of track equipped with four pairs of robotic arms. As the train rolls slowly down the track, each pair picks up an axle and scans the wheels using ultrasonic-sensor-equipped boots that are filled with water to ensure smooth transition of the sound waves. (“It’s the same as an ultrasonic medical test with silicone gel,” explains Iden.) Any defects are flagged nearly instantly.
Union Pacific hopes to have the system fully automated and operating by the end of the year. Its goal: to scan every wheel in its coal-car fleet every 60 days and “eliminate all the broken wheels and related derailments,” says Todd Snyder, Union Pacific’s director of advanced freight-car engineering. Which would save the company thou-sands of dollars per year and help it stay on track.