Seaport District to Back Bay DMU Plan

F-line to Dudley via Park wrote:it would be insane to run these things on the conventional 495-oriented routes because they're such pigs on operating cost vs. push-pull

Do you have information about the operating costs of DMUs?

Is it really cheaper to run a loco plus 6 coaches, with just one coach open (as is the current off-peak practice), versus running a single DMU?

What about labor costs? What would it take to allow an off-peak single DMU to run with just an engineer and a conductor?

Be kind and pay little attention to usually rational F-line's frothings about DMU's being useless over long distances.

He like many here loves the push-pulls dearly, and no one's had the heart to tell him about Europe yet (or Japan!).

Sometimes the US passenger rail scene bears more resemblance to the Island of Sodor than it does any sort of rational rail ops, with Amtrak and every commuter transit agency playing the collective role of the Fat Controller, keeping the loyal push-pulls alive out of sheer sentimentality (but the F40ph was a really useful engine!) While on the mainland, nearly all engine-and-coach service was long ago replaced by the onslaught of the soulless multiple units.

Rev. Awdry would be proud.

EDIT: Here's my idea to keep everyone happy:
Paint a screamer blue with red stripes, hook it up to some orange-painted Pullman flats, and give it the Needham line. (to Forest Hills only, except for on special occasions when it gets to go into the big station!).

Europe is a completely different game. Generally shorter runs with more stops. They have significantly less freight traffic too, so safety standards have to be looked at in a very different light. We have more grade crossings too for the most part. Look at all the grade crossing collisions over the past 4 months. The most deadly was the MN EMU collision. Look at the Metrolink and Amtrak collisions, imagine if the trains were even lighter?

DMU/EMU have their advantages in several places and would work well in the US. But you really can't shoe-horn them. Push-pull may be logical for some lines while MUs may be more logical on others. But it's unfair to say people are supporting push-pull purely based on nostalgia. I actually really like some of the DMUs over in the UK, but I don't think they are so versatile that they can completely replace traditional traction.

One important advantage of RDCs (and probably DMUs in general, but I don't know UK or European history & details) is that they're easy on the track compared to locos built to US passenger service standards. This mattered a lot to the B&M, but I think the MBTA lost sight of it as state & federal capital projects to 'rebuild' track supplanted a lot of routine maintenance. But I'm not sure how much this would be evident on today's T with the FRA regulating track standards, even for the Fairmount line as stand-alone DMU.

In 2012 my wife and I were in Germany. We took a paddlewheeler cruise down the Rhine from Koblenz to Rudesheim. While watching the scenery go by, I saw ALL KINDS of traffic going by on the adjacent rail lines. ICE express trains, normal intercity trains, lots of freight trains (I was rather surprised by that since "there's little freight in Europe" had been a common theme but, then, there's hardly any freight in New England where Iive) and EMUs. We decided to take an EMU back to Koblenz after having dinner in Rudesheim. It was fast, convenient, comfortable...

I don't think I've ever seen an *electric* freight train before or since then (except in pictures)

Bramdeisroberts wrote:Be kind and pay little attention to usually rational F-line's frothings about DMU's being useless over long distances.

He like many here loves the push-pulls dearly, and no one's had the heart to tell him about Europe yet (or Japan!).

Dial back the snark, pal. I have outlined several times the payoff range of DMU's where it handsomely exceeds that economics of push-pull, outlined exactly where push-pull exceeds the economic efficiency of DMU's, defined the grey areas where they blend in, detailed the types of service patterns that nail it and types that blow it, differentiated about why this purchase is different from the all-DMU RDC era, and cited evidence to back it up. I am also firmly in the camp that Indigo service is a Very Good Thing™ that Should Be Done™. But at the end of the day it's a service, not a vehicle. And the vehicle purchase has to match the service. If they are backpedaling from implementing the service, or have no financial wherewithal to implement the service...then that directly impacts the wisdom of proceeding with the vehicle purchase.


You can feel free to make a counterpoint whenever you damn well please. No one's stopping you.

Sometimes the US passenger rail scene bears more resemblance to the Island of Sodor than it does any sort of rational rail ops, with Amtrak and every commuter transit agency playing the collective role of the Fat Controller, keeping the loyal push-pulls alive out of sheer sentimentality (but the F40ph was a really useful engine!) While on the mainland, nearly all engine-and-coach service was long ago replaced by the onslaught of the soulless multiple units.

Rev. Awdry would be proud.

And again...you can feel free to cite your own supporting evidence instead of making blanket proclamations and rolling eyes at other posters.

EDIT: Here's my idea to keep everyone happy:
Paint a screamer blue with red stripes, hook it up to some orange-painted Pullman flats, and give it the Needham line. (to Forest Hills only, except for on special occasions when it gets to go into the big station!).

Actually...since they have to have the service become a reliable bet for reality before the vehicle purchase becomes wise, that's exactly what'll make the DMU purchase become a rationally expedited priority. Put together a few sets of 4-car flats and F40's for Fairmount rigged up with PoP and run the real-deal Indigo headways. It might even work better if they could relax the 4-car consist minimum requirement and run 2-3 car sets like Metro North and SLE do. < 4 cars is a restricted-speed light engine move on the T...but because of T maintenance standards. Many RR's do it when they have the need to...and this would be such a reason to start.

boblothrope wrote:

F-line to Dudley via Park wrote:it would be insane to run these things on the conventional 495-oriented routes because they're such pigs on operating cost vs. push-pull

Do you have information about the operating costs of DMUs?

Is it really cheaper to run a loco plus 6 coaches, with just one coach open (as is the current off-peak practice), versus running a single DMU?

What about labor costs? What would it take to allow an off-peak single DMU to run with just an engineer and a conductor?

It depends on a number of factors:

-- Layovers. Inside-128 lines are within easy roaming distance of the terminals so BET, Readville, and Widett (or that Beacon Park yard they're talking about after the Pike realignment is done) can serve as the sum total home bases for the entire Indigo/DMU network, with just idling spots needed at the end stations before hitting their next clock-facing inbound slot back to base. Whereas the 495 lines all have to have staffed layovers and the layup tracks reconfigured with plug-in pad compatibility for DMU's where they currently are only equipped to serve outbound-facing locomotives. And have longer required layovers because of the wider-spaced--and more irregularly-spaced--frequencies oriented around peak-vs.-off-peak with occasional freight slots sandwiched in. So the vehicle segregation by 128 vs. 495+ endpoints is MUCH cheaper to operate as 2 distinct sets of equipment then blurring the fleet assignments or doing one-size fits all. The outer layovers don't have to be overstaffed for more complex or frequently-running vehicles...the home bases can run the highest-frequency part of the network from well-consolidated points at better staff efficiency. That was my general point about the RDC era in New England: it was an ops outlier nationwide, and B&M's reasons for doing it were quite different (mass consolidation of passenger equipment into one make and "That's our story and we're sticking to it") rather than the vehicle itself unshackling them from from perceived flaws in diesel pull/push-pull.


-- Fuel efficiency. As I mentioned, DMU's have by necessity much smaller fuel tanks than a locomotive. And their shrunken engines are high-performance diesels with higher RPM rate vs. the "low"-performance (somewhat a misnomer) prime movers in a loco that spin much slower but generate much more power per spin because of their vastly larger surface area and better inertia of motion for keeping it spinning. Therefore, the DMU is going to be somewhat less fuel efficient by operating hours, and because of the smaller fuel tanks will have to spend more hours per week offline waiting for a fuel-up (exacerbated by every car in the fleet needing to do it). Which is also a problem with the layover situation, because they'll have to skip more trips on account of being nearer to the "E" on fuel gauge on more trips per week to the outer terminals. On some of the longest lines like Worcester and Fitchburg, that could even necessitate installing refueling facilities at the layover...something none of them (maybe just Pawtucket???) have because no loco is ever so low on fuel out there that they can't run all the way back home (or even +1 more revenue trips) on their own fumes.

Where the equation balances itself is that locos have to work much harder on acceleration hours-per-week when they're assigned to the schedules with the densest stop spacing...while DMU's do not. So these Indigo routes that stop every 1/2 to 1-1/2 miles are miserly affairs for DMU consumables, and not so much on the push-pulls. Push-pulls, on the other hand, are very very miserly at cruising speed--not a whole lot worse than idle--and work much better on wide-spaced stops than DMU's, which have to work a little harder with their wimpier and faster-spinning engines to stay at track speed. This is one reason why Lowell--with its low platforms--is a less-urgent DMU need. You can, because of the available convenience of switching the Haverhill schedule over to the NH Main and *approximating* Indigo frequencies...probably get as-good-or-better fuel efficiency on a short-turn trip to Anderson as a DMU because the stop spacing is so broad. Especially given that Wedgemere and Mishawum bring nothing to the table even at high frequencies and can safely get cut on EVERY service if they trade in that stop pair for a Montvale-ish situated Woburn infill.


-- Trainset configuration. Note that every time a trainset gets taken apart and recombined you're burning labor, OOS time (because they get in line and wait for the yard switcher to slowly shunt cars around), real estate (it's space-intensive work to shunt around multiple tracks, even for self-powered cars...and yard space is at a premium), fuel, and safety risk (slow-speed yard whoopsies during shunting the single-most common type of train accident). Therefore, it is cheaper to run a 6-car set with 4 cars blocked off on that last 10:30pm run of the night with 12 passengers onboard than it is to break/recombine everything to its timeslot-specific passenger load. Also...certain times of day you are running off-peak revenue trips to get a monster trainset ready in the outer layover yard for the next peak shift. So it's really only economical to do trainset reconfiguration weekday vs. weekend, or buffered several hours from the next peak/off-peak flip when the yards are less busy. The same is true for DMU's despite not requiring a switcher and being easier to break apart on a tail track. So you need to have them right-sized for the job. Multi-car DMU consists handling 495 schedules can't just be broken apart and recombined on a whim because of the whole layover + fuel capacity issue at the outer extremes of the system requiring them to spend more time closer to home...and there needing to be increased staff at the layovers to stage those moves. And because of that...you'd have to run oversize sets on the off-peak side of shift changes to the outer layovers; they're already fuel-inefficient for that role before you factor in the big under-capacity lash-ups that would entail. This is exactly the reason why the Foxboro DMU talk is insane. Conversely, the Indigo headways simply don't need the seating and you're wasting capacity with a push-pull on a dense-spaced route where they already work harder out of a dead stop than DMU's. Worse fuel efficiency for the push-pulls. But...running an empty set on a wide-spaced route involves a lot of cruising speed where push-pulls are fuel sippers. And most of the weight they carry during the service day is human weight, not steel weight. A few closed-off K-cars doesn't impact performance when the last Providence oubound of the night is sending 7 mostly empty cars out to restock Pawtucket layover for the A.M. commute. Just stand on Beacon St. above Yawkey station different hours of the day and watch the difference for yourself...an F40 has no trouble pulling a six-pack on the off-peak, but it struggles like hell to pull out of the station when those cars are full.

Of course...correct staffing is key. The 1-conductor-per-2-cars rule means you have to be exacting about not overstaffing those off-peak push-pulls that only need the front couple cars open. Something MBCR was awful at doing. And for DMU's you can easily see where those staffing costs can get away from them on the 495 runs because of the seating configuration. 2 x 2 seating in single-level cars with interiors broken up by more doors, no vestibules, and more aisle roaming space for quick-board/quick-alight between intermediate stops are less space-efficient crowd swallowers than the 3 x 2 bi-levels where everyone's staying seated until they reach the terminal and the vestibules allow for cattle-corraling people off the platform and seating them while the train's in motion. Especially now in the bi-level area where fewer conductors can serve more people. Whereas 3 x 2, narrow isles, bi-level stairs, and vestibule-only boarding in a coach is a lousy configuration to trip around for passengers doing a short Readville-Morton St. quick-on/quick-off jaunt.

See the Foxboro criticism...do you really want to be using 1-1/2 times as many cars in a DMU lash-up to pick up a swollen parking lot's worth of passengers at 7:00am? How much more staff-inefficient is that going to be than a six-pick of bi-levels bursting at the seams with passengers but only needing 3 conductors.




So, yeah...the operative phrase is: "built-to-purpose". There's two very divergent services on our idealized Purple Line that differentiate right at Route 128 and work at their absolute best efficiency working one side of that service divide per vehicle (with possible exception of the platform-tricky NH Main, for obvious technical reasons). And have worse service efficiency than before switching or mixing roles. There's no one-size-fits-all. There never was. It's all aboutcareful, efficiency-minded fleet assignments, being consistent about those assignments, and letting the characteristics of the type of service the schedules on each side of the divide are catered to (peak/off-peak @ 495+ vs. clock-facing @ 128 turns) drive the fleet assignments. After all, the vehicle isn't the service...the service is the service.

GE45tonner wrote:Europe is a completely different game. Generally shorter runs with more stops. They have significantly less freight traffic too, so safety standards have to be looked at in a very different light. We have more grade crossings too for the most part. Look at all the grade crossing collisions over the past 4 months. The most deadly was the MN EMU collision. Look at the Metrolink and Amtrak collisions, imagine if the trains were even lighter?

DMU/EMU have their advantages in several places and would work well in the US. But you really can't shoe-horn them. Push-pull may be logical for some lines while MUs may be more logical on others. But it's unfair to say people are supporting push-pull purely based on nostalgia. I actually really like some of the DMUs over in the UK, but I don't think they are so versatile that they can completely replace traditional traction.

In terms of LD service, I'll grant that Europe is a completely different game. Their longest "long distance" services all have station densities on the same level as Amtrak's NEC Acela service. However, everything short of that has densities that are along the lines of Amtrak's regular NEC service, not to mention their commuter services whose station densities are no different than ours.

Those things all being the case, the DMU is still king over there, and the only places where you still see loco-hauled trains are on their LD services (same as how Amtrak does it) and on their older high-speed trainsets such as the TGV's and the Intercity 125/225 trains. Everything short of that has already been (or is in the process of being) switched over to DMUs, EMUs, and DEMU dualmodes.

My hunch about why the US is still so wed to loco-hauled service is that it comes down to one thing and one thing only: money

Most people running passenger railroads today (from the CEO's to the crew chiefs) are boomers who came into the rail industry during the dire days of the 1970's and 80's. Passenger rail had just gone belly-up and been reanimated as Amtrak, and the crumbling regional/commuter passenger rail ops of the dozens of now-dead Class 1's were in the process of being taken over by public agencies with evan less money to work with. It was a period of endemic underinvestment in American passenger rail where even the "savior" locomotive (the F40ph, duh!) was basically a decades-old roadswitcher with a HEP system tacked on. Everyone, from Amtrak to the T, was forced to make loco-hauled work because it was what they were given, and the managers/maintenance guys who came of age in these austere times came away with an extremely conservative approach to rolling stock and rolling stock procurement that persists to this day. The ragtag fleets of the late 70's and 80's, the Amtrak F45's hauling rusty legacy coaches(some of which had been hauled around by steam engines at one point), or Caltrain running old SP trains, or creaking MBTA FP10's dragging around gutted RDC shells because that's what those cash-strapped agencies were stuck with, gave way to the shiny new push-pull sets of today.

It didn't help that the last couple generations of Budds were dudd's, but I'll wager that the early teething problems of the Metroliners and the SPV2000's would have been a footnote to successful decades-long careers had they not hit the rails when their owners were either going bankrupt or had already done so.

Compare that all to Europe, where their private railroads all went bankrupt in the late days of steam and were all nationalized at a time when passenger rail wasn't a marginal distraction like it was in the days of Amtrak, but a vital lifeline to these countries. As a result, British Rail, SNCF, Deutsche Bahn, etc all had much bigger budgets when it came to equipment procurement, so they were able to push through the early DMU/EMU teething problems and embrace this more advanced solution in a way the US RR's never could.

F-line to Dudley via Park wrote:

boblothrope wrote:

F-line to Dudley via Park wrote:it would be insane to run these things on the conventional 495-oriented routes because they're such pigs on operating cost vs. push-pull

Do you have information about the operating costs of DMUs?

Is it really cheaper to run a loco plus 6 coaches, with just one coach open (as is the current off-peak practice), versus running a single DMU?

What about labor costs? What would it take to allow an off-peak single DMU to run with just an engineer and a conductor?

It depends on a number of factors:

[snip]

That's a lot of words, but not a lot of data.

How many miles per gallon do DMUs and locos get, for runs with frequent stops and ones with widely-spaced stops?

How far can each go on a tank of fuel?

I can't make any sense of what you're saying about a staffed layover at 495 having a harder time with DMUs than push-pulls.

boblothrope wrote:

F-line to Dudley via Park wrote:

boblothrope wrote:

F-line to Dudley via Park wrote:it would be insane to run these things on the conventional 495-oriented routes because they're such pigs on operating cost vs. push-pull

Do you have information about the operating costs of DMUs?

Is it really cheaper to run a loco plus 6 coaches, with just one coach open (as is the current off-peak practice), versus running a single DMU?

What about labor costs? What would it take to allow an off-peak single DMU to run with just an engineer and a conductor?

It depends on a number of factors:

[snip]

That's a lot of words, but not a lot of data.

How many miles per gallon do DMUs and locos get, for runs with frequent stops and ones with widely-spaced stops?

How far can each go on a tank of fuel?

I can't make any sense of what you're saying about a staffed layover at 495 having a harder time with DMUs than push-pulls.

BUT! BUT! BUT!

Those Eisenhower-era RDC's on the B&M were less fuel efficient than those Carter era F40s are!

That's the extent of the anti-DMU logic in these parts.

Let's just pretend that those 90's and 00's DMUs with fuel-sipping common-rail diesels, diesel/electric drives, and selective engine shutdown don't really exist...

And if they do, they're obviously such unprofitable fuel-sickers and maintenance hogs that the for-profit private operators in the UK go so far as to base their entire regional/long distance services on them when there are dozens of spare locos and coaches to pick from. Wait, what?

I would suspect that part of the dynamic is that in Europe, given a passenger-centric system there are economies of scale in DMUs (but not in diesel locos) but in the USA the freights have encouraged a high volume low price domestic supply of locos (and blame the FRA for making sure DMUs were/are rare, low volume & expensive short production runs). Once locked in, this is hard to change.

Arlington wrote:I would suspect that part of the dynamic is that in Europe, given a passenger-centric system there are economies of scale in DMUs (but not in diesel locos) but in the USA the freights have encouraged a high volume low price domestic supply of locos (and blame the FRA for making sure DMUs were/are rare, low volume & expensive short production runs). Once locked in, this is hard to change.

To be fair, they were also swimming in standalone diesel traction (including the kinds of low-HP light duty road locos that we never got, locos that would supposedly make mincemeat of the DMU's pulling short consists if you believe people here), but they quickly realized that frequency was god, and absolute capacity was something you told yourself to fall asleep at night when you didn't have the money for frequency.

Multiple units own frequency in a way that loco-hauled consists never will. They accelerate faster, they brake faster, they're much more easily scaleable (with electric MU connections to allow coupling/decoupling on the fly), and they have the potential to be much more fuel efficient because their use of highway-duty diesels means that the efficiencies seen in those mass market engines (that will never be seen in the medium-speed engines because there isn't the sales volume to support the R&D for stuff like common rail injection, etc), not to mention the cheap parts/maintenance supply chains are now put into play in a way they never were and never will be with the bigger mills.

They're also arguably a fair bit more resilient in actual service (with proper maintenance though!), as an individual motor failure doesn't necessarily have to knock out, brakes, HEP or the entire trainset the way it certainly would with a loco-hauled unit, again allowing your DMU to limp along on its other motors to preserve the service frequency in a way you never could with a malfunctioning loco.

But again, it comes down to cost. A HSP46 costs 5-6 million, and an R-car costs 2.5million, and so a HSP46 pulling a consist of 8 R-cars will have an initial purchase price of $26 million and will be capable of hauling 1500-1600 passengers at a whack (or 600 passengers if we're talking the Fitchburg line and you're pulling 4 flats and a Rotem). On a typical MBTA line, they run a train like that every 30 minutes AT MOST, and more often than not, more like every 45 minutes to an hour on peak. Splitting the difference between the best and worst cases in terms of timetables and capacity, let's say we're moving 1000 seated passengers every 45 minutes with what we have, or ~1300 passengers/hour. So let's say that an HSP46 pulling 6 Rotems every 45 minutes could do the trick, at $21m in equipment to provide that service.

Now let's look at a modern, up-to-date medium-range DMU, the BR class 185 of the Siemens Desiro family, with all sorts of toys like selective engine deactivation etc. First TransPennine spent £260m on 51 3-car sets, which comes down to roughly $380m USD, or $7.5M per 3-car set. Now the Class 185 is a regional DMU and seats 170 people at a roughly Amfleet-level density. Since the Amfleet seats 84 to a BBD flat's 120, let's assume that a Class 185-era DMU would seat ~250 in commuter trim. Now given the Class 185's much easier ingress/egressing via it's subway-style doors and ample vestibule space, let's assume that standing isn't quite the nuisance that it is with end-boarding coaches of the sort the T runs, so let's say it could handle 280-300 passengers in rush-hour mode. Now, instead of running that one 1000-seat train every 45 minutes to hit that 1300 passengers/hour throughput that the MBTA would have to run, you could run 4.5 3-car DMU's an hour, OR combine trainsets into 2-3 6-car trains per hour depending on what your terminal would handle. The only problem is that it costs you $33m in rolling stock to hit that 1300 passengers/hour number, or 150% of the cost of doing it with push-pulls.

Now that sort of service is the kind of service that would beget MORE ridership, not less, as the added convenience would be incredible to commuters in this ever busier world (imagine if missing your train or having a mechanical failure made you only 10-20 minutes late for work/home instead of 45+, what a world would that be!), and you could bet that even in that 4-5 3-car trains/hour scenario you might well end up having to expand your trainsets to handle all that potential extra capacity, not to mention the off-peak ridership you could attract with even a train every 30 minutes.

But as long as we live in a society where we freely subsidize the highway system without ever really asking what it cost us but never want to fund the trains (because DURR, I never ride the T so why should I have to pay for it DURR, funny you never hear the people in the cities who rarely drive ever say that about the highways...), transit agencies will always be crunched for cash in a way rail travel simply isn't in Europe or Japan (where they long ago realized that the economic benefits of running high-frequency rail service far outweigh the up-front costs), that 150% cost increase to purchase MU's for proper transit frequencies versus stick with the Fred-Flinstone push-pulls that you run at regional rail frequencies and try to pass off as effective commuter transit will always come back to bite you every time you try and shake the tree a little.

boblothrope wrote:

F-line to Dudley via Park wrote:

boblothrope wrote:

F-line to Dudley via Park wrote:it would be insane to run these things on the conventional 495-oriented routes because they're such pigs on operating cost vs. push-pull

Do you have information about the operating costs of DMUs?

Is it really cheaper to run a loco plus 6 coaches, with just one coach open (as is the current off-peak practice), versus running a single DMU?

What about labor costs? What would it take to allow an off-peak single DMU to run with just an engineer and a conductor?

It depends on a number of factors:

[snip]

That's a lot of words, but not a lot of data.

How many miles per gallon do DMUs and locos get, for runs with frequent stops and ones with widely-spaced stops?

How far can each go on a tank of fuel?

I can't make any sense of what you're saying about a staffed layover at 495 having a harder time with DMUs than push-pulls.

Hartford Line Implementation Study: http://www.ct.gov/dot/lib/dot/documents ... _-_Ch8.pdf" onclick="window.open(this.href);return false;

p. 17. Using the now-defunct Colorado Railcar FRA-compliant (i.e. "SPRC"). This would be the money quote you're looking for. . .

Fuel Efficiency – A single SPRC consumes fuel in the range of 1.5 to 3.4 miles
per gallon[13]. A conventional passenger locomotive consumes fuel in the range of
0.25 to 0.5 miles per gallon. For a single car operation, the fuel savings with a
SPRC are impressive and often compelling. (However, the fuel savings available
from SPRC operations erode with increased train length since the fuel
consumption increases linearly with SPRC train length. Locomotive fuel
consumption does not increase linearly as coaches are added to its train.)

I Googled around for just a DMU-on-DMU comparison and was surprised to read that those lightweight Stadler DLRV's were waaaay bigger fuel-burners than the heavyweight FRA-compliants. And those don't even MU in most of the places they're used. Weight seems to be lot less a factor than power output, and Euro vs. U.S. seems to be meaningless. Some of these models are diesel-electric vs. diesel-mechanical, which are totally different propulsion complicating it further. Loco-on-loco also has a pretty wide range, although that's more about how big a HEP generator you're using. Amtrak's P42's are at the extreme bottom end of fuel efficiency...BUT, they also have monster electricity demands put on them by intercity cars cars so apples/oranges vs. commuter rail and carry the most powerful HEP generators on the continent because of it. Likewise a purple-paint F40 pulling a 4:00pm six-pack to Franklin where people are spending the hour-plus to Forge Park with their laptops plugged in is going to burn more than the very same F40 pulling the very same six-pack on the 6:45 to Needham carrying the same number of passengers...solely because the shorter trip means their electrical doohickeys aren't all plugged into the wall at once.

So the T's going to fare worse than, say, MARC...even though they could put together exactly the same trainset of an MP36 hauling K-cars. Just because this is Boston, not Maryland. Which makes the accounting really use-specific and really user-specific. I'm going to take a not-so-wild guess here that electrical outlets--or running them on schedules where lots of passengers are going to use the electrical outlets--may not be such a hot idea on a purple-painted DMU given how much HEP load plays into the overall fuel efficiency.


So. . .

Where do the train lengths stay (or need to stay) all-around the shortest to serve demand without waste: 128-terminating service, to neighborhood walkup stations with steady trickle of commuters. Efficiency advantage: DMU.
Where do the train lengths stay (or need to stay) all-around the longest to serve demand without waste: 495-and-beyond service, to park-and-ride-oriented stations with heavy--but not steady--bursts of commuters. Efficiency advantage: push-pull.
Where do the train lengths vary the least from uniformly short for the most # of scheduled runs per day: clock-facing Indigo service with little dropoff in off-peak frequencies. Efficiency advantage: DMU.
Where do the train lengths vary the least from uniformly long for the most # of scheduled runs per day: peak-oriented 495 CR service with large majority of the daily scheduled trains packed into the rush hour slots and dramatic dropoff in off-peak frequencies. Efficiency advantage: push-pull.

Two distinct service profiles, each getting more efficiency out of one vehicle but not the other.
-- Inside-128, with frequencies that don't change much peak vs. off-peak, with ridership demand that's a steady all-day trickle and more gradual bleed-in/out from rush hour.
-- Long-haul, with frequencies dramatically different peak vs. off-peak, and ridership demand that peaks dramatically at rush and craters off-peak.

Mix up the two service profiles too much, and you'll either venture straight into a demand cavity or be unable to keep up with capacity.


Keep in mind:
-- It's costly, labor-intensive, and racks up out-of-service time rather than road time to have to break and recombine trains all day long to constantly adjust lengths. They don't even do it on Red/Blue/Orange for exactly the same reason, so this is mode-neutral reality. It matters the world how many trains per day you can keep the same trainsets together. And matters the world the % of those scheduled trains where you'll be running too full or too empty at that length. Go by raw train trips per day. Off-peak empties aren't a big drag when the schedule is skewed so heavily to rush hour that there's few off-peak trains period. Running short sets isn't a problem when next train's always going to be in 15 minutes away any time of day to disperse a crowd. Running empty too many times per day is a problem (running empty AND overstaffed even worse). Running sardine-can too many times per day is a problem, and drains revenue when the conductors can't get through the aisles to take fares. So where do you best split the difference on car capacity without wasting time/money splitting up sets in the yard or gambling too high/low?

-- The time spent and not spent at layovers matter. If the demand calls for split-personality schedule with very dense service at peak in commute direction and light service off-peak and contraflow direction, you need outer layovers to operate because incoming/outgoing traffic and incoming/outgoing staff are imbalanced-by-design. Resupply will always be needed from one end, and excess supply will always accumulate at the other end until they trade places at the next peak. If the demand calls for clock-facing schedule you want to turn around quickly and get back to home base and spend as little time laying over as possible. Some other train's going to have to go into service to cover the next 25-min headway while the conductors run to the Dunkies down the street from Middleboro or Bradford or their first meal in a few hours. Get 'em turned around sooner and on shorter travel time to home base and you'll have more money to pay for all those extra clock-facing extra off-peak frequencies. Two different service profiles = two different types of turnback practices dominating the service day. Turning-back empty when the demand skews heavily unidirectional is waste; laying over is efficiency. Laying over is waste when the schedule's short and regular; turning-back ASAP is efficiency.

-- The *types* of equipment each flavor of the schedule is set up to handle matters. The equipment bases--inner yards and outer layovers--all have plug-in pads to allow the engine to shut off while feeding electricity off the local grid to keep the cars hot/cold, keep the lights on, etc. It matters what vehicle those pads are configured for, because push-pulls (pass-thru HEP cables) and self-propelleds (MU trainlining cables, electricity supply generated by each individual car instead of one source passed front-to-back)...don't plug in the same way. You can install layover pads to handle both types of vehicle. But that's pricey. Easier to rationalize that cost if you're dualing-up the pads at the Big 3 terminal yards and not the Big 3 yards AND all 11 outer layovers. If you run the DMU's on the schedules where they don't have to lay over out of town...you don't have to spend a giant wad modifying the layovers. Which is efficient when everything about their configuration favors frequent, short-distance turnbacks and everything about the demand profile for frequent service favors short-distance and quick turnbacks. On the other hand, the loco-only plug in pads are spread out by 495 for a reason: if the whole damn fleet lived permanently at BET/Widett/Readville overnight from running short-distance/quick-turnback service they'd have to spend a metric ton of money on way more plug-ins at the yards! Equally wasteful. It matters that they keep their stories straight on fleet assignments: mix the roles, spend a fortune installing train-idling equipment.


So...plug in some trains-per-day figures on each schedule profile. Then plug in the ridership demand per schedule profile. Start fiddling with the variables until they cross that magical Route 128 dividing line onto the other service profile's turf. Watch the costs zoom off-scale as the roles get mixed and go back on-point when roles align. You can get some basic staffing efficiency metrics that way, some basic ops support efficiency metrics that way, some basic car capacity efficiency metrics that way. And when you've established car vs. staff vs. schedule...THEN you can "solve for x" and see who's being a fuel pig and who isn't when matched to what role. And could do the same if you had the conductor payroll figures and a price quote from "Pimp My Layover, Inc." on what it costs to do a facilities retrofit. I don't have that, and couldn't even begin to suggest where to look...but you can get the gist of it loud and clear doing a little algebra and simplifying for the x value.

Hint: build-to-suit, because the singular magic-bullet fleet doesn't exist.

Bramdeisroberts wrote:

boblothrope wrote:

F-line to Dudley via Park wrote:

boblothrope wrote:

F-line to Dudley via Park wrote:it would be insane to run these things on the conventional 495-oriented routes because they're such pigs on operating cost vs. push-pull

Do you have information about the operating costs of DMUs?

Is it really cheaper to run a loco plus 6 coaches, with just one coach open (as is the current off-peak practice), versus running a single DMU?

What about labor costs? What would it take to allow an off-peak single DMU to run with just an engineer and a conductor?

It depends on a number of factors:

[snip]

That's a lot of words, but not a lot of data.

How many miles per gallon do DMUs and locos get, for runs with frequent stops and ones with widely-spaced stops?

How far can each go on a tank of fuel?

I can't make any sense of what you're saying about a staffed layover at 495 having a harder time with DMUs than push-pulls.

BUT! BUT! BUT!

Those Eisenhower-era RDC's on the B&M were less fuel efficient than those Carter era F40s are!

That's the extent of the anti-DMU logic in these parts.

Let's just pretend that those 90's and 00's DMUs with fuel-sipping common-rail diesels, diesel/electric drives, and selective engine shutdown don't really exist...

And if they do, they're obviously such unprofitable fuel-sickers and maintenance hogs that the for-profit private operators in the UK go so far as to base their entire regional/long distance services on them when there are dozens of spare locos and coaches to pick from. Wait, what?

Grow up. Preferably before a really good substantive discussion gets nuked by Act of Mod. You're the one causing a scene sprouting hyperbole, engaging in childish name-calling, and refusing to contribute factual point/counterpoint while flinging that accusation at others. I'm not even disagreeing with you on anything fundamental. I think DMU's are great for Indigo...just implement th' Indigo. When did commuter rail motive power purchases devolve into a sports rivalry? Or "Locomotives have always been at war with DMU's, like Oceania has always been at war with Eurasia." Where did that come from???

How do the fuel bills compare to the labor cost and the above-the-rails equipment cost?