Trinnau wrote: ↑Fri Feb 26, 2021 9:44 amMBTA has clearly set direction for the next 15 or so years with their newer HSP46 fleet, rebuilds of the F40 fleet and procurement of bi-level coaches to replace the remaining aging single-levels. But the board has also clearly indicated a desire to move toward electrification and to explore MU-style service in certain corridors, and the existing fleet lifecycle will get them to a point of being ready to purchase new vehicles which will likely be EMU-type.
MBTA is an interesting case in regards to DMUs. For most commuter operations in the Northeast, running lightly trafficked outer branches with DMUs makes a lot of sense, and should absolutely be done. There are some lines, like Greenport, Montauk, Waterbury, Wassaic, and maybe Springfield that are perfect use cases for 4-car DMU sets. DMUs are far more efficient for trains that are 4 cars or less, and most routes that require more than 4 cars should be electrified, with a few exceptions for routes that cannot handle a high frequency but still need the seat capacity, like Port Jervis, or in the case of MBTA, Old Colony and Greenbush lines, since they are bottlenecked on single track, so they can't simply run twice as many half as long trains which is the better option on double tracked lines and where terminal space is available.
Due to the physical arrangement of the North-South rail link trackage, all lines except Old Colony and Greenbush need to be electrified in order to run through the rail link. Whether the Old Colony/Greenbush lines should stay as diesel push-pull, run with longer DMU trains that accelerate a bit faster, or be electrified at low volume is debatable, but for the foreseeable future, they would make sense to stay with diesel push/pull as other lines are electrified.
All that being said, we should have a northeast standard DMU design that fits over third rail, and those clearances are a lot tighter than anything needed for the MBTA, but I still don't see a compelling case for where the MBTA would use DMUs.
west point wrote: ↑Sat Feb 27, 2021 9:53 pmIt really seems to this poster that multi level EMUs are the way for MBTA to meet 2040 anticipated demand. There is a problem that I am un aware how it can be fixed. Is the bridge in Boston on the B &A route to Worcester still a low clearance restriction ? Can it be raised or replaced some way ?. Also does it impede the direct access to the Grand crossing track ?
Multi-level cars should be treated as a last resort once train length is as long as possible, and as many trains are running as can physically run. Even for Penn Station on NJT, they seem like a band-aid until Gateway and the expansion of Penn. The multi-level cars needed in the Northeast for high-level platforms are cumbersome to load and unload, and increase dwell times compared to single level coaches or EMUs. The electrified MLs are also going to lose some seating capacity and end up being really heavy if they work at all.
Interestingly, for those few applications where diesel push/pull makes sense, as well as for properly powered loco-hauled electric (not pushing 12 MLs around with a single loco), single and ML cars have almost identical weight per seat. Thus, a 5-car ML train has about the same weight and seating capacity of a 7-car single level train, making the 7-car single level train the better option. MLs really only make sense in capacity constrained terminals where there is no other option, and then they should have at least one electric per 6 cars. The long and thin diesel push-pull routes should be fine with a single locomotive and 5 MLs or 7 single level coaches.