When GE was designing the AC60, they intended to offer a single diesel unit powerful enough to pull a train single-handedly. They painted a picture of high speed strack trains zipping across the country led by a single AC60, but it didn’t turn out that way. The railroads, instead, chose to pair a couple of 4400 hp units on the theory that if one fails you still have adequate power to get over the road, but slower. So that begs the question: Just how reliable are today’s diesel units? Do they really fail so often that they are continuously in need of backup? Or are the consequences of a failure so dire that a railroad can’t risk the occasional traffic jam?
In steam days is was common to move a train with a single locomotive, with helpers where necessary. I can’t believe a steamer was more reliable than a diesel, but maybe most steam failures didn’t mean a complete loss of power while diesel failures are more likely catastrophic.
So does anyone have statistics or personal experience that can shed some light on the question of just how reliable a diesel is?
Current models are delivering in the high 90s availability rates. That measures the amount of time the locomotive is available for service vs. the amount of time it is not. Time not available includes refueling, FRA inspections, program maintenance, and unplanned maintenance. Thirty years ago we were seeing availability rates in the high 80s.
About 8 years ago, I kept track of how many locomotive failures I had over a six-month period during my shift on my territory that caused train delays. Average trains per shift per day was 35. Average days per week 5.5. Total trains measured, slightly more than 5000. After eliminating collisions with vehicles, rocks, trees, large animals, and washouts, locomotives running out of fuel, and crew mistakes such as forgetting to release handbrakes on a DPU, the answer is .
the idea that the railroads put 2 engines on 1 train as a back up if 1 fails is by far a joke. if you have 2 units that is because the first unit is withun 90% of tonage so they add a unit to help get you down the road, then they figure since you have all that power we will just add a few more cars ( no need in wasting power) to your train. there is the rare instance that you are hauling extra power for a extra train. and if you have a 3700 ft 2200 ton train and 3 big units ( 4000 hp units) and think man i can get across the road fast with all on line, you will be the slowest train the most over worked engineer out there. first your gong to be speeding then you get dynamic and then your going slow then you get throttle now your speeding so we get dynamic and on and on and on. Back to the question when the dash 9s came out there was not a day that went by that you
I do remember reading once, but remember this is an exception, that Penn Central used to throw a lot of units on some trains, expecting at least one to fail. This of course had to do with the condition of this railroad, but on some lines they couldn’t take a chance of a train breaking down and blocking everything.
I 've heard it said that GE unit’s are cheaper in price than EMD But not as high quality. Also thay don’t last as long. An EMD unit however is more expensive but lasts longer. And is also more expensive to run. Each builder has it’s own por’s and con’s. Just whatever the R.R. is willing to pay for. Also as stated before, you will have as many unit’s as you need for youre load. Putting a loco on the train in anticapation of one failing would just be a waste of fuel as far as I’m concerned. Besides, correct me if I’m wrong here, it’s probably not all the time that a unit fails. If it is a nucler flask train, that is a horese of a diffrent color though. Feel free to correct me if I’m wrong though anywhere in this post.
Today’s yardmasters and locomotive managers take great delight in putting 14997 tons behind power that is rated for 15000 tons. Doesn’t make any difference to them if that locomotive consist is one, two or more units. Maximum tonnage for the available power.
Thanks everyone for responding to my question. Your answers were very informative and authoritative. I suspected the idea that second units are primarily backup was bogus and you confirmed that. I did not realize how widespread is the impact of a failure on the road. The dominoes fall every which way and in ways the outsider wouldn’t imagine. It is interesting that the early dash-9s were so trouble prone, but often that it the case with new designs. It takes a while to work the bugs out. Thanks again for your observations and viewpoints. They shed some real light on the subject.
One major difference in road failures between steam and diesel locos.
Unless the diesel has a traction motor failure that immobilizes the axle, the unit can usually be moved, even if not under its own power.
Steam failures tended to be semi- to fully catastrophic. Break a rod, and it will flail everything off that side of the locomotive [N&W J - generator 1/4 mile out in a farmer’s field. MILW - engineer’s side completely wiped out (lubricator failure.)] Let the water get low and you orbit a boiler…
Of the two, I’d rather by far be aboard a diesel when things go sour.
The severity of the conseqences of a failure depend on the trains involved. CSXT has sometimes added a third unit to two-unit consists in intermodal service to ensure that, if one of the other units fails, the train has enough horsepower to meet its schedule; and it has also sometimes added a third unit to coal drag consists to ensure that the trains will not stall if the other units do not meet their tonnage ratings.
Actually the SD90MAC and AC6000CW were marketed as 2 for 3 unit reduction ( 2 6,000HP units replacing three 4,000HP units). Most road freights in North America need more than 6,000 HP. However unit reliability was a problem as a train would lose half it’s available tractive effort with a failure…
If I may add a small quetion here… I have seen locomotives that throw fire from their stacks on URDVDS. Is the locomotive failing?
Also, You were talking about the AC6000CW in youre orignial post. UP of course scrapped their entire fleet of them. This locomotive looked better on paper than it actually was in real-world conditions. 6000 hp isn’t enough for an intermodal train but 2 of them is way too mutch.
I think that another reason that you saw more Steam locomotives handling a train single handed is that the railroads had a lot wider variety of motive power to chose from in the steam era. Such as the Union Pacific, even many of their 1910’s era 2-8-0’s soldiered on right up to the end of steam in the late 50’s Then they had 2-10-2’s, 4-12-2’s 2-8-8-2’s 4-6-6-4 and 4-8-8-4’s as well as others available. They matched the locomotive to the load and terrain to be crossed. If a 2-10-2 wasn’t upt o the job, call out a Challenger, or Big Boy to handle the train.
The later Challengers were designed and intended for a large part to work hand in hand with the Big Boys. The Challengers were built to handle a train that a Big Boy handled throught the Wasacht Mtns, take the same train through the lesser grades, and hand off that train off to a 2-10-2, or 4-12-2 in open country. A large part of this wide variety of power was due to the inability of Steam locomtives to MU, each Steam locomotive must have its own crew, so basically build a double Mountain (4-8-2) into a Big Boy, and you only need one crew to control the effective power of two locomotives. The diesel has the advantage of being able to consist together as many locomotives as needed, even DPU’d, and control all of them with one crew.
Also a steam loco has unlimated hp. And a set torque. So a steamer would be able to handle a bigger load. I found out that the Challengers were made to take a train at high speed across the prarie, after the BB’s too took them over the pass. Thanks for including this Doug!
The economics is driven by labor costs, not locomotive costs, then and now.
In the steam era, railways matched the tonnage to the steam locomotive, not the steam locomotive to the tonnage, and strove to reduce the labor costs more than anything else. The idea was to load the steam locomotive to the maximum it would just barely haul over the division. Alignments were laid out in an concerted effort to concentrate all the heavy grade into one short section and keep the grade everywhere else the same to avoid wasting horsepower. For example, a district might be engineered so that there were five 1% grade
Fear of unit failure was not and is not the problem. The problem is this: there are very service designs in the U.S. that economically favor a locomotive consist with 12,000 hp but only 300,000 lbs of continuous tractive effort, as opposed to a locomotive consist with 12,000 hp and 450,000 lbs. continuous tractive effort, or multiples thereof. The 6,000 hp locomotive has been a locomotive in search of purpose and need. If it had one, there would be a lot more incentive to solve their technical problems.
The economics is driven by labor costs, not locomotive costs, then and now.
In the steam era, railways matched the tonnage to the steam locomotive, not the steam locomotive to the tonnage, and strove to reduce the labor costs more than anything else. The idea was to load the steam locomotive to the maximum it would just barely haul over the division. Alignments were laid out in an concerted effort to concentrate all the heavy grade into one short section and keep the grade everywhere else the same to avoid wasting horsepower. For example, a distr