(I"m not sure the point of calculating the whole train weight)
It's to maintain congruity for the A>B>C calculation steps, Toronto Rockets' weight is only published in 6-car formations. The others only have published 1-car weights.
But even for the rail head [...] then it was designed for a pressure of 463 MPa, but 465 MPa is too heavy?
If you have the time to read about the G-1s, you'll find that they were incredibly overweight compared to customer specifications. The system at the time certainly was not expressly designed for the G-1's weight. This led to the G-2 and G-3 being redesigned and rushed in within 2 calendar years of Line 1 opening, which was also due to higher than expected ridership. The later G-Series were revamped to save several tons, in part by using more aluminum. I would not put it past the TTC to normalize deviance and think heavier trains were ok for their outdated ballasted sections when they procured the Toronto Rockets. If they had the capital budget, they would've fully switched to ballastless by now. See quote at the end of this post.
Are saying that I'm wrong, and the Gloucesters didn't have a higher axle load?
I agree that it had a higher axle load, but the contact stress was lower. See the above chart and sentence below:
Contact stress leads to fatigue and cracks, which dominate long-term maintenance costs, unlike axle load, which primarily drives lower-cost routine wear.
For the rail head perhaps --- won't do anything for the rest of the system. The big issue we keep hearing about on the Bloor to Eglinton section of Line 1 is trackbed.
Contact stress absolutely does affect the rest of the system, including the trackbed, ballasted or otherwise. It usually matters more than axle load regarding damage progression and maintenance costs. Regarding how badly a farmer’s tractor compacts a field, what matters more, how heavy the tractor is, or how much PSI is exerted through its tires (i.e., how that weight is spread over the contact area).
Contact stress is calculated from axle load and other variables. Contact stress is how the axle load is concentrated into a tiny area. Axle load is exerted through a contact patch, which creates
contact stress (pressure). It's not the axle load itself that wears anything down. However, axle load
does set the baseline for trackbed loading (ballast and ties), but contact stress governs rail damage, which in turn drives the dynamic forces that actually destroy ballast and ties. Furthermore, it is much cheaper to maintain & fix ballast and ties than maintaining and repairing rail.
This axle load vs. contact stress thing is almost about semantics. The Toronto Rocket
will induce more non-vehicle maintenance costs than the long-retired G-1s, as well as the T-1s etc... Where TRs theoretically save money is for vehicle maintenance, as the trains themselves are much more reliable.
Contact stress + load cycles--->rolling contact fatigue is detected through ultrasound and eddy current testing. This is done to find cracks and chips in the metal rail that may not be visible to the human eye. RCF is remedied by expensive rail grinding and welding.
Feel free to look up how expensive it is to deal with RCF.
"Construction proceeded smoothly until the weigh-in of the first completed cars. The cars tipped the scales at 40% in excess of their estimated weight. The cars weighed 85,525 lbs compared to the estimate of 60,900 lbs. Some quick calculations revealed that the traction system could handle the higher weight, but modifications had to be made to the braking system to compensate for the additional load. Some hasty weight reduction measures were able to bring the total weight down by a full ton, but only after the first 30 cars were already substantially constructed on the assembly floor. This grave weight miscalculation would dog the cars for their entire operating life."
(I"m not sure the point of calculating the whole train weight, and then going back to axle ... columns 4 and 5 seem unnecessary to me ... but if there's any importance to this (and I don't think there is), then the mass of a G1 train is 684,200 lbs not 513,150 lbs. But it cancels out because a G1 train has 32 axles, not 24.)
You are right, I overlooked this making the chart, the G-series cars were shorter, heavier, could run up to 8-car consists. But like you said, axle count per train is the same, so it doesn't affect the subsequent numbers.
Genuinely don't know what they were thinking going from aluminium to stainless steel, new ASME crash standards maybe? I doubt it though... Just sounds like typical Toronto transit ineptitude. Instead of meeting stricter standards with better design, they switch to heavier materials. See Williams F1 team as of late.
