Why don't we use bidirectional diesel locomotives in the US?

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Why don't we use bidirectional diesel locomotives in the US?

Postby bostontrainguy » Fri Nov 10, 2017 9:19 am

LOCO.jpg
LOCO.jpg

Seems like in the US we totally avoid an option which might just be a better solution in many respects. Why don't we use more two-headed bidirectional diesel locomotives? Simple run around tracks could be built or possibly even available in many cases.

Now you have ONE engine per train instead of overpowering a short train with two locomotives. You have the ability to add a revenue coach by removing a trailing engine or cabbage which increases income. You avoid the costs of building a wye if you even have the room to do so.

Why do we completely avoid this concept? Routes like the Downeaster is an example where this would work well.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby electricron » Fri Nov 10, 2017 9:28 am

Because it takes time to uncouple and recouple the locomotive to the trains, and manpower to un-connect and reconnect the brake hoses and electrical cables. It's much simpler and quicker to just have cabs on both ends of the train vs both ends of the locomotive.

That second cab doesn't have to be in a second locomotive or ex-locomotive, it could be in a passenger car equipped with a cab. Even RDCs have cabs on both ends ( a passenger car and locomotive all in one).

Even so, the engineer would walk to the other end of the train to use the cab in the last RDC rather than uncouple, run around, and recouple the first RDC.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby Gilbert B Norman » Fri Nov 10, 2017 9:37 am

Here is the only example of a twin cab bi-directional Diesel locomotive coming to mind:

https://goo.gl/images/wGgD1n
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Re: Why don't we use bidirectional diesel locomotives in the

Postby bostontrainguy » Fri Nov 10, 2017 9:50 am

electricron wrote:Because it takes time to uncouple and recouple the locomotive to the trains, and manpower to un-connect and reconnect the brake hoses and electrical cables. It's much simpler and quicker to just have cabs on both ends of the train vs both ends of the locomotive.

That second cab doesn't have to be in a second locomotive or ex-locomotive, it could be in a passenger car equipped with a cab. Even RDCs have cabs on both ends ( a passenger car and locomotive all in one).

Even so, the engineer would walk to the other end of the train to use the cab in the last RDC rather than uncouple, run around, and recouple the first RDC.


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Re: Why don't we use bidirectional diesel locomotives in the

Postby EuroStar » Fri Nov 10, 2017 10:36 am

The "easy" answer would be that this avoids the cost of the second cab making the locomotives cheaper. That does not hold water well though. The Sprinters have two cabs and NJT ALP 44/46 also have two cabs even though they are exclusively used for push/pull. The "toasters" which were a European design also had two cabs. So why is it that electrical locomotives deserve double ended cabs and diesels do not?

Most European diesels have double cabs, but even Siemens built the Chargers with one cab only. The ALP45s have only one cab too, but that might be due to length limits.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby JamesRR » Fri Nov 10, 2017 12:04 pm

EuroStar wrote:The "easy" answer would be that this avoids the cost of the second cab making the locomotives cheaper. That does not hold water well though. The Sprinters have two cabs and NJT ALP 44/46 also have two cabs even though they are exclusively used for push/pull. The "toasters" which were a European design also had two cabs. So why is it that electrical locomotives deserve double ended cabs and diesels do not?

Most European diesels have double cabs, but even Siemens built the Chargers with one cab only. The ALP45s have only one cab too, but that might be due to length limits.


Interestingly, the ALP-45DP is single cab, and it's a dual mode loco. Obviously more space is needed inside to house extra equipment which was likely the reason. But I suppose also since push-pull operations don't really demand dual-cabs the loss wasn't a big deal.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby Arlington » Fri Nov 10, 2017 12:41 pm

Would this be fair to say:

The electrics tend to operate:
- in markets demanding fast turns and tight timekeeping
- at WAS where they're swapped on/off
Being nimble during tight, frequent, time-sensitive turns are good reasons to be double ended.

Diesels:
- run in markets with lazy once-a-day turns
- run on longer/heavier/HEP-intensive trains that often demand two locomotives
- run on remote routes where reliability demands two locomotives
- are often derived from freight diesels (which tend to operate in pairs or more)
- often run paired with a cab, so as to put exhaust on the far end of terminals
So between lazy turns and double-ended pairs, the second cab just isn't worth it
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Re: Why don't we use bidirectional diesel locomotives in the

Postby Ridgefielder » Fri Nov 10, 2017 12:57 pm

Gilbert B Norman wrote:Here is the only example of a twin cab bi-directional Diesel locomotive coming to mind:

https://goo.gl/images/wGgD1n

Those early "oil-electrics" built for the CNJ and the CNW back in the '20s had two cabs, too. So did the 1800hp demonstrators that EMC built for the B&O and the Santa Fe in the mid-1930's.

I can think of a couple reasons why dual-cabs didn't catch on in North American usage.

1. Our trains tend to be much heavier than those in Europe. Most need more than one unit anyway, so there's no point in going to the expense of equipping every single unit with two cabs. In fact we even have diesels with no cabs. (Side note- do B units even exist in Europe?)

2. The widespread adoption of the road-switcher type (Alco RS, EMD GP, etc.) in the 1940's and '50s. The North American loading gauge is big enough that an engineer in the seat of say an RS-3 has a decent view whether the unit is operating long-hood-forward or short-hood-forward. I don't think that's the case in the tight clearances of Europe.

Just my 2 cents.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby scottychaos » Fri Nov 10, 2017 12:59 pm

CNJ purchased double-cab Baldwins for commuter service:

Image

But they were the only US railroad to have double-cab diesels, and they only had six of them.

DL&W was considering dual-cab E-units for commuter service.
they were in talks with EMD about building them..(no idea how far along the process ever went..)
but in the end of course it never happened, DL&W went with FM Trainmasters instead.

I photoshopped what they might have looked like:

Image

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Re: Why don't we use bidirectional diesel locomotives in the

Postby SwingMan » Fri Nov 10, 2017 1:11 pm

Current passenger locomotives in America (P42, HSP-46, DE30AC, etc) are already incredibly heavy and long locomotives. What would end up happening is getting smaller engines, which would require more engines per train and the added cost of having to run more of everything.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby David Benton » Fri Nov 10, 2017 9:10 pm

Would it not also require a brake test, whereas engineer changing ends does not ? That often seems to be a reason given for not switching cars in and out enroute.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby Backshophoss » Fri Nov 10, 2017 9:24 pm

Changing ends requires a brake test,however whenever you break/make connections to the brake pipe,a more extensive brake test routine is
required.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby mmi16 » Fri Nov 10, 2017 10:03 pm

bostontrainguy wrote:
electricron wrote:Because it takes time to uncouple and recouple the locomotive to the trains, and manpower to un-connect and reconnect the brake hoses and electrical cables. It's much simpler and quicker to just have cabs on both ends of the train vs both ends of the locomotive.

That second cab doesn't have to be in a second locomotive or ex-locomotive, it could be in a passenger car equipped with a cab. Even RDCs have cabs on both ends ( a passenger car and locomotive all in one).

Even so, the engineer would walk to the other end of the train to use the cab in the last RDC rather than uncouple, run around, and recouple the first RDC.


Time for us to come into the 21st Centry . . .
https://www.youtube.com/watch?v=kpf2f5dPIFg


US uses the Janey coupler system - the YouTube'd system doesn't. In the US on Class 1 trackage there needs to be compatibility with other equipment operating on the tracks.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby bostontrainguy » Sat Nov 11, 2017 9:19 am

mmi16 wrote:US uses the Janey coupler system - the YouTube'd system doesn't. In the US on Class 1 trackage there needs to be compatibility with other equipment operating on the tracks.


Oh, I know that. It's just an example of what can be done with (not even that new) technology. LRVs couple and uncouple all the time with a push of a button. There are several different types of auto couplers out there. I'm sure Amtrak could retrofit some automatic system.
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Re: Why don't we use bidirectional diesel locomotives in the

Postby electricron » Sat Nov 11, 2017 9:35 am

bostontrainguy wrote:
mmi16 wrote:US uses the Janey coupler system - the YouTube'd system doesn't. In the US on Class 1 trackage there needs to be compatibility with other equipment operating on the tracks.


Oh, I know that. It's just an example of what can be done with (not even that new) technology. LRVs couple and uncouple all the time with a push of a button. There are several different types of auto couplers out there. I'm sure Amtrak could retrofit some automatic system.

There are passenger trains running in the USA using automatic couplers. Every single example runs on dedicated passenger tracks, or on tracks owned by the passenger train company. As long as Amtrak runs trains on shared tracks owned by freight railroad companies, they will have to use whatever coupling systems the freight railroads demand. Because so much of the USA railroad corridors are single track, the freight railroads require Amtrak to use the same couplers they use to ease clearing the tracks of disabled trains. Therefore, you will not be seeing auto couplers on most Amtrak trains anytime soon.
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