Review of NJT’s Dual Mode Feasibility Study
March 24th 2007 11:40 pm
Courtesy of Tom Schulze of NJTransit I obtained a copy of the NJT Dual Mode Feasibility study. I found it to be a well written document and it does identify all the important issues and challenges.
It rightly concludes that while a single car DMMU is not feasible without losing too much revenue space, a two or three car articulated set DMMU is possible essentially using technology available off the shelf based on either the M7 frame or any of the other standard single level commuter cars in use today. Indeed, such a vehicle already exists and is in operation in France, but of course it does not meet US FRA requirements.
(Follow the link for more details on DMMUs and dual mode locomotives.)
The report makes the following observations about the DM(M)U, which incidentally also hold true for EMUs:
1. Maximizes the space available for seats in the same train length when compared with push-pull.
2. Operational flexibility achieved because performance is independent of train length.
3. Fuel savings due to efficiency of use of engine power, compared to push-pulls.
It then goes so far as to say that these added efficiencies are likely to cancel out any perceived maintenance expense disadvantages due to the fact that each unit has to go through a 92 day inspection as opposed to 180 day ones for push-pull cars.
I wish NJT would take this to heart and start ordering EMUs (and DMUs and DMMUs) going forward and de-emphasize its infatuation with push-pulls which for reasons mentioned above, will always prove to be inferior to MUs in short inter-station distance operations.
In discussion of the dual mode locomotive the report lays out the following requirements:
1. Perform in both modes as well as a a single mode unit of same power.
2. Load up as fast as the PL42AC in D mode.
3. Perform as well as the ALP46 in the E mode.
4. Fit on a Bo-Bo frame.
5. Weigh less than 300,000lb to meet Amtrak restrictions.
6. Fit through the North and East River tunnels - max roof height 14′6″, max height to the top of locked down pantograph 14′8″, appropriately shaped top corners to fit through diverging paths at the East end of the North River tunnels.
7. Target HP ~4000 in both modes. E-mode inputs through pantograph of 11kV 25Hz, 25kV 60Hz, 12kV 60Hz.
It then goes on to identify significant challenges of fitting a 4000HP prime mover and electrical gear for equivalent power within a Bo-Bo frame. It concludes that if one uses GEVO as the prime mover then it is unlikely that such can be achieved on a Bo-Bo frame. Only a weaker E-mode can be fit in which will prove to be challenging to use through the tunnel grades. It also concludes that the EMD 710 is too heavy and big to be used for this purpose. It recommends looking into using high-speed diesel prime movers to achieve better power to weight ratio, and suggests that this need further evaluation in Phase 3. It also states that development cost will be upward of $24Million, which has to be accounted for in the price of the units, hence a small order would be infeasible, and recommends that this be done as a part of a larger order, perhaps of a mix of pure, D, pure E and Dual-mode.
An interesting additional thing that it says is that it is possible to do a trial prototype dual-mode service using a ALP46 and a leased Amtrak Genesis unit (pure diesel, not the dual mode ones) with minimal additional work on control wiring to enable control of each unit from the other and from a cab car. My immediate reaction was “A-ha! So that is what will happen for the AC service from Penn Station…. I see!”. The report clearly states that this is not a recommended long terms solution since it is woefully inefficient use of resources to provide any service on a regular basis.
It should also be noted that they looked in detail at third rail based solutions and shy away from proposing a 3rd rail solution due to a few issues:
1. Only way to reliably solve the gap problem in Penn Station is to have two units per train, which is not efficient.
2. Expense of installing and maintaining third rail all the way to feasible changeover points in NJ.
3. Expense of establishing maintenance facilities and training for yet another kind of power system.
Few beefs that I have with the report are:
1. It does not explicitly present any information on the issue of transformer weight.
2. It alludes to the use of IGBT power technology to achieve better power to weight ratio, but it is not clear whether they are suggesting that there is some way to use IGBT to reduce or eliminate the weight of the transformer. Also there is no mention of the weight of the IGBT modules if such substitution is possible.
I am hoping this information will be forthcoming in phase 3.
Being a report from a consultant for a customer, it naturally does not outright reject the idea of a dual mode locomotive, but states that further evaluation is being carried out in phase 3. There is a lot of useful information using data sheets for all existing units they looked at. Surprisingly they even looked at the Channel Tunnel Class 92 to see how third rail shoe loads are managed for such a high power unit!
I found it a good read which is based on an honest appraisal of the situation but then packaged in sugar coating that the masters will find palatable.
One thing that I don’t quite understand is how the phase 3 that is mentioned in the document is related to the RFP that is allegedly about to be issued by NJT at least for the EMU/DMMU acquisition. Is it the case that the information for Phase 3 will actually be collected via the responses from the RFP? I could not say for sure.
On the whole the report covers all bases fairly and makes resonable recommendations, some of which make a lot of sense even in making choices between electric push-pulls and EMUs, irrespective of what happens to dual mode versions of MUs and locomotives.