Jill Jonnes Conquering Gotham: Building Penn Station and its Tunnels is an excellent read. I am reading it for the second time; I suspect one could read it four or five times and find something different in each read.
As I understand it the rings in the tunnels were made of cast iron. Would these rings not be susceptible to rust and other forms of deterioration over time?
Not if enough rugged rust-preventive coatings were applied. Like autobody undercoating.
Wonder since PRR was involved with the H & M tubes if they were of the same type construction ? ? I seem to remember that Path had some major problems with their Hudson river tunnels ? ? But Yikes if the North river tunnels are of cast iron there is a major potential of one failing ?
Eh… I don’t think it is that much of an issue since almost all of the PRR, H&M and subway tunnels under both the North and East rivers were built of the same construction. If the deterioration of cast iron in salt water was such an issue, all of New York would be one heap of trouble at this time. No alarms about the eminent demise of any tunnel in New York City (except the subway Montague Tunnel) so I don’t think rusting cast iron is a big deal.
Just for the record, the Montage subway tunnel in lower Manhattan is falling apart because of the amount of salt water that poured in the tunnel during Superstorm Sandy and wrecked all of the equipment in the tunnel. Even though the tunnel did reopen for about 8 months, everything was still falling apart to point where it was surprising no passengers ever died going through the tunnel… that how bad it was according to some MTA employees. So it looks like the biggest threat to the tunnels is rusting/deteriorating from the inside out as oppose to the outside in.
The problem with the H&M tunnel was that the engineers in charge of construction got careless. They were not careful with their measurements and allowed the tunnel shields to get out of line with each other. Consequently, the shields had to be turned to get back in line (not an easy task) and there is a slight kink in that tunnel.