With 28,000 locomotives, more than 1.4 million rail cars and enough rail to circle the earth more than thirteen times, railroads rely on advanced technologies to monitor the health of the vast 140,000 freight rail network and the equipment moving across it. From ground-penetrating radar used to detect problems beneath track to a vast network of wayside detectors used to identify equipment in need of repair, railroads are at the forefront of developing and deploying advanced technologies that further improve the freight rail industry’s impressive safety record.
Internal flaws in railroad tracks — caused by use and impurities introduced during the manufacturing process — are largely invisible to the human eye. Today, railroads employ defect detector cars and HiRail trucks with GPS, induction and ultrasound technology to help locate and identify these internal rail defects before they cause an accident. In addition, the world’s first laser-based rail inspection system is being developed at the Transportation Technology Center (TTCI), the railroad industry’s world-class rail research facility in Pueblo, CO. Due in large part to technologies such as these, accidents are at an all-time low; track-caused accidents per million train-miles have dropped 85 percent since 1980 and 49 percent since 2000.
How do you build railroad track that safely supports trains weighing over 3,500 tons, while maximizing the fuel efficiency of trains and the lifespan of the track? Through track geometry: the three-dimensional geometry of track layouts that encompasses everything from the alignment and elevation of track to its curvature and track surface. Today, railroads use sophisticated electronic and optical instruments to inspect all aspects of track geometry. At TTCI, railroads have developed on-board computer systems that provide even more sophisticated analyses of track geometry and predict the response of freight cars to track geometry deviations, allowing railroads to determine when track needs maintenance.
A strong foundation is critical for any structure — and railroad tracks are no exception. Track ballast — the foundation, often made of rock, upon which railroad track sits — helps transfer the load of the trains to the underlying foundation while facilitating drainage of water and minimizing vegetation that might interfere with track structure. Over time, ballast breakdown can occur and lead to track instability. To measure this, railroads regularly use ground-penetrating radar to measure ballast thickness and identify areas where repairs are needed.
With more than 100,000 privately-owned bridges in America’s freight rail system, railroads are continuously seeking ways to monitor bridge health and detect damage in real time. At TTCI, researchers are developing a new generation of monitoring equipment to be installed on both trains and bridges in order to provide regular feedback on the health of each bridge. In addition, TTCI researchers are conducting research to gain insight into current bridge design, component standards and maintenance practices to identify new ways to extend the lifespan of rail bridges.
Wheel bearings — or “journals” — allow the wheels of a rail car to rotate freely along track, and the journal box holds the oil to keep wheel bearings operating smoothly. However, worn or defective wheel bearings can cause enough friction to heat up the journal box and create what is known as a “hotbox.” During the early days of railroading, oil soaked wool would be placed in journal boxes to detect early signs of friction and overheating. When a journal box became overheated, the wool would smoke, alerting brakemen to an issue. Today, what was once detected with wool is now detected with infra-red technology and acoustic monitoring devices. For example, friction from a faulty wheel bearing causes a noisy rubbing sound — an ‘acoustic signature’ that can be recorded by track-side monitoring devices and used to alert railroads to early signs of stress.
A rail car’s axle and wheel suspension assembly is commonly known as its “truck.” Trucks that are in proper alignment help to extend the life of rail car components and track, and help trains use less fuel. However, when trucks become warped or misaligned, a phenomenon known as “truck hunting” occurs. Truck hunting causes a rail car to oscillate which can damage the rail. To prevent truck hunting, railroads rely upon a laser-based monitoring system — truck bogie optical geometry inspection or TBOGI — that measures the alignment of a rail car’s truck and identifies trucks that are not performing optimally.
Similar to smart alert systems on many automobiles, advanced monitoring systems alert railroads when a train wheel is in need of repair. Wheel images captured by lasers show worn wheel treads or flanges, indicating when the wheels on a rail car need to be replaced. Meanwhile, wheel impact load detectors are used to measure vertical wheel loads as rail cars travel across track, and alert railroads when a wheel is warped and needs to be repaired or replaced.