Jeff Smith wrote: ↑Fri May 14, 2021 8:34 amThey've backed themselves into a corner by basically procrastinating on their replacements, not by the lack of electrification.
Procrastinating on their replacements just means that they get new dual modes later. If they had actually planned ahead and electrified, the dual-modes wouldn't be needed.
That's not to say that some electrification extension is not worth it. However, DC electrification extension is by its nature very expensive with the need for many more substations. When MNRR electrified the Upper Harlem in the early 80's, they did a poor job of it, underestimating the power draw of the M-1's and 3's. Except for some short LIRR projects and Penn Access, I don't see DC being extended anywhere.
Much of the LIRR system can't provide enough power for full acceleration of M-7 sets, and as you note, the Upper Harlem system can't handle full length trains. Extending DC power makes perfect sense for OB, PJ, and Patchogue, as the LIRR is an entirely DC system. The cost to do dual third rail/overhead EMUs and have two separate fleets would be astronomical.
The 20-year plan for MNRR at some point talked about extension of the Hudson to Peekskill; Poughkeepsie is a "Bridge too Far".
That's an application for AC overhead, switching at Highbridge, so that Amtrak could electrify to Albany with AC from Penn, MN Penn Access could run on AC, and freight wouldn't have to deal with third rail. Harlem would still have 3rd rail access to Yankees-153rd.
No mention of the "upper" Upper Harlem. It's 53 miles GCT to Southeast; it's another 29 to Wassaic. That's a lot of work for very little yield. DMU's would work instead of shuttle mini-Bombs; maxi's for through service.
They only have four through trains a day to Wassaic. They could just get rid of them, and add sidings to do more frequent DMU shuttle runs. I can't see any case for electrification beyond Southeast. Fixing the current system so that 12-car M-7 sets could come into Southeast does make sense, however. Depending on what is done with White Plains, a diesel train or two a day could go down there from Wassaic.
Danbury? That's been bandied about for years, but always written off as too expensive for the yield. The 45's would be ideal for through service on Danbury, and Waterbury (to New Haven or Stamford), if those could be routed to Penn.
It was electrified at one point, it would make perfect sense to put it back in order to handle direct service to GCT and Penn.
Ditto OB.
PJ I'm not too sure; that is a little farther.
PJ has a lot more traffic than OB. OB makes sense simply to provide direct service. Unfortunately, they now need to fix the screwed up track arrangement that they are building right now in Mineola. OB is the lowest priority out of the branches affected by the dual-mode situation.
Pensyfan19 wrote: ↑Sat May 15, 2021 5:23 pmLike I said in the BEMU topic, I can't help but feel that the introduction of M7/M9 BEMUs on diesel routes might make dual mode replacements moot..... 
BEMUs are, at this point, completely unproven in US heavy rail applications. Traditional electrification has been working reliably for over 100 years, and can electrify routes in the dozens of miles (DC) up to the thousands of miles (25kV AC).
HMUs are actually a more promising technology. While hydrogen cars are probably a non-starter due to lack of fueling infrastructure and up-front cost, for a basically captive fleet of trains that run back and forth, it starts to look a lot more attractive.