Myrtone wrote:Is it true that gauge differences preclude joint venture orders anyway?
As far as the vehicles are concerned, no - it's just a matter of using different trucks (bogies). That was done when the broad-gauge M4 cars were retrofitted for use on the NHSL during the car shortate 30+ years ago. The real issue is things like station clearances, curve radii, etc. That depends on how different the two systems' configurations are, and whether there's enough commonality for a base design to have system-specific modifications.
... is it true that converting either of the Philadelphia network to standard gauge would be more complicated than it's worth
Almost certainly yes, because all of the buried street track would have to be dug up rather than simply having rails shifted as with surface-mounted rails, and in the meantime nothing could run. I can't speak for what if any modifications would be needed to the tunnel infrastructure, though.
...even though their track gauge differs enough from standard gauge to physically allow dual gauge track? Too much disruption?
Probably. First, the tunnels would have to be converted because they're shared with all five lines. Then, unless there were a practical way to segregate operation of the standard-gauge and broad-gauge cars by route number while each was converted, the entire subway-surface network would have to be shut down until the last piece of rail was laid. Not to mention political fallout - there'd be volcanic complaints about cost, etc. PA's Act 89 has given SEPTA a badly-needed infusion of cash but it only begins to address a 5B USD backlog of SOGR work, let alone expansion projects that've been postponed for decades.
Bottom line, we've suffered for well over a century with the effects of having the Pennsylvania Gauge imposed on street railroads. In all that time no one's been able to figure out how to accomplish regauging at an acceptable cost in effort or dollars. Sadly we're probably stuck with that incompatibility.
Requiem for it's/its, your/you're, than/then, less/fewer. They were once such nice words with such different meanings...