Then again, it’s not supposed to.
When Trains attended a 2016 University of Wisconsin-Madison Engineering Professional Development course in Philadelphia on the topic, this editor-author had delusions of learning about the latest in positive train control tech. Instead, I joined a group of at least two dozen from throughout the rail industry to learn about SCADA systems, interlockings, and operations fundamentals.
“They’re not all going to be experts, the objective here is if they go to a meeting that’s signal related, and comments come out like approach blocking, or PTC, or CBTC that they’ll at least say, oh yeah, I remember that,” says Robert MacDonald, one of the course’s co-instructors.
The course is aimed at professional engineers, finance people, or other railroad workers who, co-instructor James Hoelscher says, “are in a division where they don’t really deal with signals, but people around them do.”
For an insight on how signal systems work and why getting them right is important, I offer key takeaways below — but taking the class over two days gives you continuing education credits. What not everyone takes advantage of is the conversation with MacDonald and Hoelscher. During a seminar lunch break, I asked to two insights on railroading and systems.
First on PTC. As it is being implemented in the U.S., PTC is an overlay system. It essentially sits on top of and relies on the functionality of wayside systems and signals to do its job. So … in addition to the software and new PTC hardware, there is whatever signaling system is in place, tested, and functioning on a given railroad. All of those existing components and systems must work correctly for the whole system with PTC to function.
That’s the reason for a full day on signaling and train control fundamentals in the course.
Then, there’s getting qualified workers to install new systems.
“Because of PTC you have a huge demand you would not normally have had, at one time,” Hoelscher says of tradespeople working toward the Dec. 31, 2020, PTC implementation deadline. “You’ve got this huge demand because it has to be done now, it has to be done quick. And you would normally not have had that big bubble, all of a sudden.”
And then there’s the problem of railroading in general — worker turnover.
“I often say that when I first started working and I had called a meeting, it was not uncommon that I could have 125 years of experience at that table, [the meeting would include] 5 or 6 people,” MacDonald says. “Today, it’s significantly less. It’s probably 10 or 20 years. [That] would be the most experience I could pull out of that group. And so decisions are made that are not as experienced as they were…”
The kind of experience is useful when it comes to saving money and working with components from different manufacturers from different time periods. Knowing what to replace and when, and how to shift priorities.
“You try to put together a design [for a signal system] that will try to provide you with the flexibility you need to maintain operations. Because the real issue today is not replacing, it’s maintaining an operational environment,” he says.
But even though technology may be improving with digital advances, “The real penalty that we’re paying is the life expectancy of these systems — the ability to provide the replacement components over what used to be traditionally a 30-year life cycle. It’s now probably closer to 8 or 15, or maybe at most 15 years,” MacDonald says.
And it often makes more sense to buy new systems than replace old ones, in part because re-producing circuits or parts may cost as much as buying new, but without any advance in function.
Rail signaling systems, key takeaways:
•PTC can be non-vital, says MacDonald. That means that the fail safes built into wayside signals and equipment stay in place even after new systems get installed. CBTC, or communications-based train control, is the name for the kinds of signaling and control systems that don’t need wayside failsafes, or vitality.
•Fail safe — a signaling system is “fail safe” if you can prove it does not have a failure within … 1 billion (1,000,000,000) operating hours.
•Track circuits still matter. Until future versions of PTC become “vital” and independent of wayside signals, the way most signal systems detect trains on tracks and trigger signals and response is through electricity passed through rails. This means ohms, carrier frequencies, and cosines matter as well as problems with broken rails, artificial shorts (shunts), and so on. The required know-how can’t be waived away by computer code.
•Signal systems basically do two things: regulate capacity and ensure safe train movements. A change in track speeds, for instance, could change both the capacity of the railroad and the safe stopping distance for individual trains. That may require adjustments to signals. In fact, almost any change from track structure to locomotive performance could require a review of signaling.
