Reports suggest that the operator of an eastbound car failed to check the setting of the east-to-north switch, drove into the intersection and turned into the path of a westbound car. Reading the Globe article, I can’t help thinking that a discussion of the situation and the history of streetcar switching is badly needed.
TTC officials say it is the driver’s responsibility to check that every switch on the tracks is aligned properly before proceeding, a rule established in 2002 to avoid accidents like yesterday’s.
From other background, it appears that the Dundas route was diverting on Tuesday evening around events at Dundas Square, and the east-to-north switch would have been left open for that diversion.
Most of the TTC’s streetcar switches – little steel arms on one side of the tracks where the vehicles have the option of turning – are controlled electronically by a device in the cockpit.
Well, no, actually. “Most” is quite an overstatement. Many switches are “electronic” (as I describe below), but many are not.
[Update] Bay and Dundas has no electric switches in any direction. Moreover, when the intersection was rebuilt recently, there was not even provision for retrofitting electric operation (empty switch machine casings and drains) at this location. Any discussion about electric switching in regard to this incident is utterly inappropriate.
Bay and Dundas eastbound is a manual switch. Therefore, if it is set for the curve, it would not automatically reset for the straight when a car approaches. Typically, there are more automatic switches for left turns than right turns, but this is not a universal practice. Many years ago, the TTC resisted automating switches that were part of regularly used short turns to save on the capital expense preferring instead the service delays of manually setting and resetting switches.
In practice, there are three types of switches on the system:
- “automatic” but not operational
Examples of the latter include some switches on Spadina where the traffic signal hookup has never been installed, and streetcar turns are very difficult because they don’t get a dedicated turn phase. The TTC has a particular problem when there are two closely-spaced switches (for a right, then a left turn) to ensure that operators planning to turn left don’t accidently open the right turn switch instead. This is basic design flaw as the signal transmitted by the car should include a way of selecting, definitively, one switch in a sequence.
The TTC’s streetcar switching system is archaic by modern light-rail standards, using “single-point” switches that rely on one moveable steel piece – a switch tongue – to pull one of a streetcar’s wheels onto the second track.
Most modern light-rail vehicles – including the low-floor models the TTC is considering buying – use “double-point” switches, one for each wheel.
They may be “archaic”, but they work, and the same accident would have occured with a double-blade switch. The question of which type of switch we use is completely separate from yesterday’s collision, and we shouldn’t get the idea that a massive retrofit will prevent future accidents.
Transit City lines will use double-blade switches, and there will likely be a move to gradually retrofit the existing system where practical. However, the special work renewal cycle is about 25 years long, and it will be at least 2035 before every intersection has been rebuilt.
In all the discussion about automatic switches, the TTC didn’t mention that the electric switching systems are unreliable and that there is a capital project to completely replace them.
Originally, track switches were operated through contactors on the overhead wire. When a car passed through the contactor, a button on the operator’s console sent a signal indicating whether the switch should be opened or closed. This system, dating back to the 1920s, became obsolete with the arrival of the 75-foot long ALRVs in the late 1980s because the spacing between the front of the car and the point where the trolley pole meets the overhead is different for the longer cars.
At that point, the system was changed to use loop antennae buried in the road and transmitters onboard the vehicles. To deal both with variations in vehicle length and train operation, there are two transmitters per car, one at each end. The leading one sets and locks the switch, while the trailing one signals that the switch can be unlocked. In trains, only the transmitters at the front and back of the train are active.
The system has a number of reliability problems including:
- failing electronics
- failing antennae
- false locked states due to a failure to unlock after a car or train passes
Common sights around Toronto are out of service electric switches where some component has failed. Parts are not available, and less important locations may give up their working electronics to keep critical junctions in operation.
The unreliability of the “new” switching system eventually brought on the stop-and-proceed rule for all facing point switches. This may satisfy the TTC’s love for safety, but it doesn’t do much for ride comfort as cars jerk through intersections. Moreover, it fails to address the basic issue that such equipment should be reliable. Imagine if the subway operated the same way!
Why has the TTC allowed a substandard, unreliable system to remain in operation for two decades? Was it simply that the streetcar system didn’t deserve the attention? Did anyone care that this was one more way to make streetcars look less attractive?
Yesterday’s accident happened at a manual switch, and discussions of switching electronics don’t apply here. However, they are relevant to the streetcar system overall, and it’s time the TTC took the issue seriously.