SEPTA pulls PCC trolleys out of service for at least a year

[cirdan]

It is not the cost of laying track and overhead wire. Track wok is very precise of making the sub grade very strong for the long run. That work requires all underground utilities to be located. Then it has to be inserted into conduit strong enough maintain the compaction needed for the track to remain proper surfacing. Those revision to underground utilities is the big cost.

I think this is a chicken and egg thing. The sub grade does not necessarily need to be very strong, it just needs to be sufficiently strong and there are ways to do this. The strength it needs to have is also given by the vehicles you use and once again if you go against the over-engineering and use lightweight vehicles you don't need heavyweight track. The problem with telephone cables or whatever is not necessarily that they are not mechanically strong enough to support track (they usually are, heavy trucks being far heavier than streetcars) but that there are concerns over earth currents leaking into them and causing interference, signal degradation, or electrolytic corrosion. There are smart ways to tackle these problems that don't involve digging it all up.