Published in the winter 2010 issue of MyLIFE magazine
There are approximately 150,000 miles of railroad tracks in the U.S. today, with more planned for the future.
Have you ever wondered how railroad crossing warning signals work? Brian Lehman, who serves as railroad safety supervisor with the Arizona Corporation Commission Railroad Safety Section, shares with us the technology behind the crossing signals. To ensure that Arizona’s railroad system is operated and maintained according to the highest standards, Brian’s team inspects all aspects of railroad operations, including railroad tracks, locomotives/railcars, railroad operating practices, railroad warning signals and devices and the transportation of hazardous materials. “We have people that look at the tracks, bridges, structures and facilities … the mechanical side of it—inspection of locomotives, and the railcars themselves,” Brian said. The Railroad Safety Section covers over 3,000 miles of tracks throughout the state, and those tracks include more than 600 railroad crossings.
During his 24 years in the railroad industry, Brian has witnessed a transformation in railroad operations as a result of the introduction of new technologies. In the early ‘80s, new modern electronic devices began to appear in the railroad industry. “Before the technology came, everything was done manually. There were no computers, and everything was done by clerks—entries were done by hand. The new technology was great, but unfortunately thousands of jobs were eliminated as a result,” Brian noted. The electronic components were done with an old relay system that had battery-powered relay circuits. Now it’s all frequency-based and more sophisticated. The most common system used is the Positive Train Controls, or PTC, which is satellite-based.
PTC systems are integrated command, control, communications and information systems for controlling train movements with safety, security, precision and efficiency.
This technology has improved railroad safety by significantly reducing the probability of collisions between trains, casualties to roadway workers and damage to their equipment. A GPS receiver on the locomotive receives position information, and a data radio provides communications between the train and the control center. An onboard computer and display device displays information to the locomotive driver.
So how are railroad warning signals activated? “The detection system is a radio frequency that is put out onto the track. It’s called ‘constant warning’ time circuitry—and what that does is, it judges the distance and the speed that the train is coming at,” Brian explained. There’s a federal requirement of 20 seconds of warning time needed, which is dictated by the tracks. Whether the train is traveling at 25 mph or 70 mph, you still need that minimum of 20 seconds of warning time. This “constant warning” technology not only allows for the warning time, but it also adjusts to the speed of the oncoming train to give the same amount of warning, regardless of whether the train is moving slowly or very rapidly. The goal is to give adequate warning, but not too much time.
“You don’t want an excessive amount of warning time because you encourage the public to drive around the gate and disregard the signal,” Brian said. Once it becomes a habit to see that the signal takes longer than 20 seconds, motorists start to take chances, and they will drive around the gate.
At each crossing, there’s an equipment housing that physically connects to the railroad tracks by underground cabling. Once the frequency is interrupted by an incoming train, it begins to judge where the train is. “The frequency is beginning to be shorted down because the wheels of the train actually act like a short across the rails,” Brian added. “That’s what the system detects.”
When that happens, the system starts another mechanism that reads how far away the train is and how fast it’s traveling. At that time, it turns on a relay that activates the flashing lights, and the gates begin to descend. As the train recedes from the crossing, the system monitors the train’s movement until it detects that the train has moved past the crossing. The gates ascend, and the flashing lights are deactivated.
“If the crossing gates are down and lights are flashing with no train approaching, that is a malfunction. It means that circuit has been interrupted somehow,” Brian said. This happens because the system works on a fail-safe principle. The gates will stay down until a technician can correct the problem.
Most of the diesel-powered locomotives you see on our railways nowadays haul cargo containers that originate from the ports in the West Coast. “We see an average of about 45 trains a day in our railways,” Brian stated. “They are loaded in the ports in Long Beach and L.A. The transport will go to major hubs in Texas and the Midwest, and then they will be broken down—those containers will be put on trucks, which take them to their destination.”
What does the future look like for railroads? All of the major railroads, such as Union Pacific and Burlington Northern Santa Fe, are looking ahead, 20, 30 years from now and are continuing to plan their infrastructure accordingly. “They foresee a difficult time moving the demand of goods in their current infrastructure—the way this country is using goods from other countries such as China and abroad. They are going to be the mode of transportation because they can move more efficiently than the trucking industry,” Brian noted.
We are also seeing an increase in passenger service commuter railways with the recent increases in the price of gasoline. Amtrak, the sole passenger system in the U.S., has had a 20 percent boost in ridership in the last year. This means that more railways with separate corridors will have to be constructed to meet demand. As an example, California is planning to build a high-speed corridor that will run from San Diego to San Francisco and will allow train speeds in excess of 200 mph.
People like Brian play a crucial role in the safety of the nation’s railroad system, which currently includes approximately 150,000 miles of railroad tracks. Given the likelihood that our railroad system will expand in the years ahead, his kind of expertise will be in even greater demand.
