NJ Transit is going back to the future with plans for new dual power locomotives. Unlike the old FL9’s, these will utilize overhead wires.
This brings back to the fore one of the more hotly debated topics on this forum, aka the idea of using dual power technology to aid the power requirements of modern day freights over mountain grades, without having to overpower them on the leveler grades. Would it be more cost effective to simply string wire on the steepest grades only and leaving the level track wire free, rather than using helper districts or overpowering a consist between terminals?
Don’t think it will ever happen. What are you going to do, have a special dual power fleet for just the mountain grades? I don’t think the railroads would spend the extra money to buy an entire fleet with this feature, as they have demonstated with AC locomotives. The railroads still buy DC locomotives despite the AC’s advantages in mountain areas because in the long run it is cheaper. So are the railroads just going to switch the dual power locomotives on and off the train around the mountain areas? Might as well just add helpers to the regular train and not have to pay to maintain the overhead.
What difference does it make as far as how they’re powered? You STILL have to overpower the train for the majority of the trip. Either way, you’ve got locos idling along or shut down for most of the trip, which is kind of a waste of resources. Changing the power source doesn’t change the horsepower output of the motors, does it?
Going by memory of the last discussion, I think it comes down to the traction motors. The motors on electrics were usually more powerful than those on diesel-electrics. The idea then is to have traction motors on dual powered locos that are more powerful than those on standard diesels, and they only max out when drawing from the wires, e.g. that would be the “helper” energy. Hopefully, those with experience in electric locos will clarify.
NJT estimates that the dual power locos they’re thinking of would cost $6-8M a pop! Ouch! I’d like to see the ROI on that vs. buying some P32ACs and just using the 3rd rail to get through the tunnels. A pair of P32s would get you 6000 HP for traction plus the ability to get through the tunnels for $5M or so.
The traction motors are the same, the difference is the source of the energy. Diesel-electrics are limited by the output of the main alternator/generator, dual-powers and straight electrics are limited by the output of the power plant(s) and the delivery capacity of the overhead which ties the locomotive to the power plant. Electric locomotives can have higher short-term ratings due to the availability of this excess output. DC traction motors on a straight electric will still burn out if short-term ratings are exceeded.
Another thought to keep in mind is that dual-power locomotives in the United States have been used almost exclusively in passenger service. I am aware that the FL9’s did work occasionally in freight service but the third-rail capability was not required on the freight runs and such freight service is probably analogous to locomotives in commuter pools working local freights and transfers over the weekend. At any rate, all of the current and proposed dual-powers are owned by passenger operators and such part-time freight service is no longer part of t
In Britain we’ve had dual powered “Electro-Diesel” locomotives on what was the Southern Region of BR, but the diesel engine was mainly to enable these locos to run away from the 3rd rail for relatively short periods (though on occassions these locos have wandered considerable distances north of the Thames River!).
Given that the Green Goat hybrid battery locos seem to be taking off in North America, I’m surprised no-one’s thought of equipping them with pantographs and/or 3rd rail shoes so they can use these power supplies to recharge their batteries. Green Goat have teamed up with Brush in England to convert an old BR AC Electric loco to a battery loco; whether it will have this capability I don’t know. The battery locos that London Underground use on works trains can recharge their batteries from the 3rd rail.
Knowing the economics of the particular situation, I predict:
New Jersey transit will end up buying a proven dc electric - diesel of a type already in operation by LIRR, Metro North, and Amtrak.
The existing third rails in the two Hudson tunnels will be extended 1/4-mile to the west to allow convenient changeover from diesel to electric operation. The new tunnels will be electrified similarly to the existing tunnels including both catenary and third rial.
This is an entirely different issue that electrifying freight railroading. That will come about after needed legislation is passed exempting railroads from added property taxes when rights of ways are also sued for power transmission lines and when the right of wya is improved through electrification. And allowing power companies to reenter the transportaiton business.
Your prediction makes great sense… but that’s not what Warrington is saying…and he’s they guy that brought us the too-wide, overpowered, overpriced, unreliable, poorly named (but successful inspite of all this) Acelas. Common sense, economics and what NJT will do may not have much in common in this case…
Railpower has been moving away from the small engine/large battery bank design to locomotives with two or three engines and fewer batteries. They have been finding that the battery life is shorter than forcast.