By Mike Smith
Many have been wondering what happened to the Seattle Streetcars on that fateful day where they were pulled from service. I can tell you what I know. Or rather, what I have been told.
I’d like to preface this report with the fact that the street cars are actually quite safe and seldom travel at more than 50% over their available speed.
On all railroad vehicles there is a device called a deadman. Notice I did not say an individual, I said a device. A deadman is a feature of railcars in the event an operator dies or is otherwise impaired. (The “otherwise” is a different more serious problem and involves a completely different group of civil servants.) The device, though, is a spring-loaded brake switch that activates when the handle is let go regardless of speed. The stop is gradual yet covers a very short span of track. It is a safe stop. No one is harmed and everyone is happy and may not even know what happened. The only person affected is the unlucky operator. He may need some attention.
A streetcar has at least three main braking systems. One is the dynamic braking which is the close equivalent to automotive brakes. These brakes work at the axles near the widthwise-center of the car at each end. Then there is the track brake, a friction brake that works by applying downward pressure directly onto the tracks. This brake is located between each of the dual wheels of the bogey (or truck) as it is known. (The wheels and power drive together are called the truck.)
There is a third form of braking which is also a form of traction enhancement. It is a sander. Just as it sounds, there are four tubes that protrude from the bottom of the passenger compartments which apply sand to the tracks whenever there is a slippage or perceived braking need. It is an automatic application but can also be applied manually by the operator. We also have an emergency brake that essentially applies all braking apparatuses simultaneously. Believe me, when applied, the emergency brake will stop the streetcar on a dime!
So what happened? All of the braking systems accept the deadman are controlled by the electrical system on the train. Generally, the trains have a backup low voltage system that allows for the application of the emergency brake should a power outage occur. It is supposed to be a fail-safe system that runs off the battery. Apparently what happened is that fail-safe system… uhm… er… failed.
The car in question was tooling along just fine when the electrical system shut down. This has happened on occasion but has never posed a real problem. Usually the lights go out and the operator slows the car to a stop and reboots the operating computers. About a 2-minute elapsed time and we’re up and running again. This time the car experienced this outage and the system shut everything down. Including all brakes of any kind. Yes, even sand! Since the car was heading in a generally downhill aspect, the car had a tendency, as luck would have it, to go as we say… downhill in an increasing velocity which some would consider questionable. I say, some. Most passengers were unaware that there was an issue in their darkened streetcar. They were blithely engrossed in their various and sundry personal reading/emailing/video-watching devices. A true compliment indeed to the many technological marvels we take for granted every day in the public transit sphere.
But, the driver called the communications center and reported the issue, which alerted the WA State Department of Transportation representative in his office, which in turn obligated him to call his counterpart at the NTSB. We are after all, a railroad service. Despite the careful and graceful bringing-of-the-streetcar-to-a-halt by our operator. The Feds ordered a shutdown of all cars of this manufacturer in the U.S. Not a big number of cars, but at least we were not picked on.
This is basically the same thing that happens when, say, your Tesla catches on fire for no apparent reason and the NTSB issues a recall. We found a factory defect that initiated a recall. In short, we were stopped for not stopping!
So, we’ve been down for 2 weeks. I was involved in some testing by our consulting engineering firm wherein an acceptable work-around was devised and applied. The testing was 100% effective. In turn, the manufacturer is creating a fix which should be designed, installed, and certified soon hereafter.
The end of the story is: We are operational again as of this weekend. I am also again working as an “engineer” (see last weeks’ article) and the world is a better place for it. It should be all down hill from now on.
I hope to see you on the train. If you so Desire!