Published June 29, 2019 at 1666 × 1112 in Humber Loop QEW Realignment 1973-74 ← Previous Next → Inbound to Humber Loop on the new single track alignment April 3, 1974
Fascinating pics and description! There’s lessons learned that could be re-applied in ways today, not least the energy absorbent bumpers used on the PCCs (and IIRC, some buses) in that era. These were water filled. (Note many of the pics Steve posts)
Note how even more sophisticated forms are not only being developed by the US Federal Transit Agency, they have been by Bombardier for their European Flexity models, and used in various cities there. Other versions are used in US cities.
Click to access DESIGN-AND-DEVELOPMENT-OF-IMPACT-ENERGY-ABSORBING-BUMPER.pdf
Click to access Transit77.pdf
There’s quite a few top level engineering/scientific and development studies and prototypes/production versions extant. And one of the benefits besides greatly reduced pedestrian and vehicular damage?
Much less chance that the impact energy will cause an over-ride and subsequent derailment, especially in the case of segmented LRVs with a set-back bogie at front/rear to allow the cantilever of the sections without bogies.
Ironically, the earliest TTC presentations for the Flexity Outlook showed a bulbous bump at the front ground level, along with the claim “Energy absorptive system” in the list of features. One has to wonder why that was dropped, and what lessons were learned (or not) from the much earlier fluid filled type that graced some of the earlier TTC vehicles. Doubtless the fluid filled versions would add far more weight than the newest hydraulically damped ones using the coupler mechanisms on many models. That coupler may be missing on the Outlooks, but the space exists as an empty chasm behind the fibreglass skirts now used and easily ripped off in collision rendering the front bogie prone to derailment.
Steve: The problem is to figure out a way to make the coupler and the bumper co-exist, and this is addressed by the second paper. However, I note that this only looks at vehicle/vehicle crashes, not at vehicle/pedestrian situations. I the latter case, a pedestrian does not present enough mass, let alone the inherent resistance of some sort of frame, to push back against any collision system. At best they would bounce off of it if not simply fall under the vehicle.
As to derailments, it is important to note that the particularly spectacular one recently at King and University was caused by a vehicle striking the streetcar side on where a bumper would have done no good.
The TTC bumpers were not installed on all of the fleet, and notably not on the MU equipment which can be seen in a few of these photos.
Further to my last post on “energy absorbent bumpers” and the PCCs in many of the pics in this string, according to this 1976 US DOT “State of the Art Review” reference, CLRVs were also initially touted to have them:
Pg 144. It tops the list of features.
I wouldn’t [describe] “Shriner Skirts” as in any way being ‘energy absorbing’.
Steve: The location where the bumper is shown on the drawing of the CLRV in this document actually was used for the anti-climber, a vital crash protection mechanism in its own right. Also, note that these are high floor cars, and the bumper would have been the height of the frame, just below the car. This would have struck other vehicles like autos in a different location than the bumper for a low-floor car, and would probably ride completely over some of them, especially the petite profiles now quite common.
The skirts were named after Esther Shiner, not “Shriner”, and their purpose was as much cosmetic as practical.
In searching for Cdn or Ontario regulations for Toronto streetcars/LRVs, I’ve also discovered apparently there are none! (City of Ottawa might be an exception due to being the Capital Region.) The TTC regulates itself, as best as I can determine, and that’s audited by the APTA, a TTC board meeting reviewed the latest audit just weeks back. It also means that any investigation into accidents (e.g. the series of derailments) is behind closed doors. Whether FOI could daylight that is a good question.
Perhaps the Municipal Railway Act was still in effect in the 70s when these pics were taken and it required collision impact mitigation measures?
Any comment from Steve or other informed posters most welcome.
Steve: The bumpers on some of the PCCs were a trial that was not extended throughout the fleet. It was one of those “sounded good at the time” ideas. I may have something about them in my archives, but will have to do some digging.
There is some basic physics at play here with a large, heavy vehicle striking something lighter and smaller. Some protection is possible, but the streetcar will win almost all of the time. The same is true for a bus.
Any results from digging on this would make for valuable reading. Streetcars and LRV’s *should win* most of the time, and that would be to stay on the rails, as detailed in the studies linked.
There’s a surprising amount of technical study for this on-line, but an almost complete absence of Cdn, let alone Toronto reports available to the public (and press!) as to the cause of accidents and outcomes.
An example, albeit bus:
I thank you for your considered answers, and if anyone can tease the story out of the TTC on their experience, it’s probably you.