New power for Metra, the SD70MACH

[mu26aeh]

Metra posted some photos on their FB page announcing the arrival of their first SD70MACH, with 15 total arriving in the near term, with an option of an additional 27 locomotives

https://www.facebook.com/MetraRail/

[dem34]

I know a few people who will have aneurysms over this.

[sundowner]

Former CSX SD70MAC?

[packers#1]

So at what speed is ludicrous speed exactly? Is 70 MACH going to plaid? 

[peteski]

No aneurysms here, but I bemoan the trend of using narrow hood diesels for passenger service.  That utilitarian look just doesn't cut it for me for passenger service.  This has been going on for some time (MBTA also uses narrow hood locos, and I'm sure many other commuter railroads do the same).

[mu26aeh]

Not sure on exact heritage, but a post from last year on trainorders forum suggested they were ex-KCS

[BCR751]

A little overkill for passenger service don'tcha think?

Doug

[sirenwerks]

There goes the neighborhood...

[Ed Kapuscinski]

A little overkill for passenger service don'tcha think?

Doug

No way. Metra runs monster trains. It's a big time operation.

[nickelplate759]

No way. Metra runs monster trains. It's a big time operation.

Tractive Effort may not be all that critical for commuter operations, but Acceleration is.  Horsepower is essential for both.

[wes_sutton]

I'd photograph these over any of the modern dildos that pass for passenger engines these days.

[Lenny53]

So separate HEP unit or will it run the prime mover in notch 8 like the F40?

[C855B]

Tractive Effort may not be all that critical for commuter operations, but Acceleration is.  Horsepower is essential for both.

Aha! But horsepower isn't everything!

I did an informal but published study - 50 years ago! - after SP starting replacing the Trainmasters in the San Francisco commuter service with SDP45s idled after Amtrak took over. Despite 50% more horsepower, the end result was the EMDs couldn't keep the schedules the aging FMs could. I don't recall what the resolution was other than a short-term solution where they assigned the SDPs to off-peak service only.

It was all about acceleration, but I wasn't all that technically astute at the time about loco internals to discern the issue; the article was simply comparing before and after, with charts and graphs. In long hindsight it was probably something to do with transition points and loco mass relative to train mass.

The thought I'm harboring at the moment is, frankly, the same thing with the retooled 70MACs. They were designed for the freight drag service typical of modern railroading, and are heavy beasts that will have to spend a lot of that horsepower overcoming their own inertia. It'll be interesting to see if the transition - pun intended - to the entirely different demands of commuter start/stop is successful.

[sd45elect2000]

The power output and rate are a simple software change these days. They are heavy machines so they should do fine. Remember that tractive effort is tied to adhesion the only real way to effect adhesion is to make a thing heavier.

[C855B]

Yeah, but... physics. ~208+ tons for a 70MAC vs. ~114 tons for an F40 is a lot of additional mass to overcome. Firmware can't fix that. Proof will be in the pudding.