I think it was in the 70s or early 80s that UP had some engines geared for 90mph top speed and ran some freights that fast. Why did they stop?
Freight car bearings are not designed with those kinds of speeds in mind.
(Like stated before)Too heavy of a load on the bearings for that speed. Also, I imagine that it has something to do with train lengths. And the number of trains on the rails. Please correct me if I’m wrong.
If I recall, there was also the economic factor that getting to that speed and coming back down was not cost effective especially for the amount of time the train could go 90 mph; nor was the wear and tear on the track worth it. In other words, for frieght trains, there was no real or substantial gain that warrented the speed.
Regulations also come into play. FRA Class 5 track has a freight speed limit of 80MPH. Higher speed would require Class 6 standards and maintaining the specs for that level would be prohibitively expensive for modern heavy freight operation. Generally Class 5 track is only found on busy mainlines that handle fast intermodal trains. This 2006 on line article by Kevin Keefe http://www.trains.com/trn/default.aspx?c=a&id=232 says that Class 6 and higher is only found on Amtrak’s NEC, but I think the upgraded section of the ex-GM&O Chicago-Springfield line and Amtrak’s Michigan line are 6.
In the late 1970’s through early 1980’s, UP had some SD40-2’s numbered in the 8000 series which were equipped with 59:18 gearing, which has a theoretical maximum speed of 90 MPH, analogous to the theoretical maximum of 71 MPH for 62:15 gearing. These locomotives were intended to run in a dedicated intermodal power pool along with the Centennials (6900’s), which had similar high-speed gearing. The speeds of the trains involved was probably in the 70-75 MPH range. At any rate, keeping the high-speed power in a separate pool was probably more bother than it was worth and the SD40-2’s were re-geared back to 62:15 and returned to their intended numbers in the 3000 series.
I have a vague recollection of an ancient article that stated when passenger trains got to 88 MPH (?) there occurred a dynamically unstable reaction in passenger trucks ( dont remember if it was 2 or 3 axel ) that had to be compensated for by additional equipment in the truck. (was easily corrected and AMTRAK has no problem). Does anyone know of this type action? If so would that preclude 90 MPH running on freight trucks? Also maybe this type action is why Auto Train limits their auto carriers to 70 MPH?
Another key factor is overall train speeds. As can be seen today courtesy of Amtrak, running a train faster than the general flow is as disruptive as a very slow train. It’s far more efficient, overall, to run all of the trains at about the same speed.
The biggest time waster is terminal dwell time. If you can cut terminal dwell time on a hotshot to near zero, it will get over the railroad in fine time.
Nobody knows what speeds they actually ran, but timetable speed limit for UP freights was always 70 or less, with the possible exception of that short-lived UPS train a few years ago.
SFe allowed the Super C 79 mph-- AFAIK no other American RR ever allowed their freights 79.
I highly doubt UP ever ran freights at 90mph…or even above 79 in the diesel era.
In order to run trains at such speeds, some form of control system is required by law. I believe this ruling dates to 1947.
Because of this law, the Santa Fe installed Automatic Train Stop (ATS) over significant portions of their mainline. This was done so they could continue running passengers trains over 79mph. Thanks to this, the present day Southwest Chief is the only long distance Superliner train allowed to travel at 90mph. The present day Surfliner also benefits from the Santa Fe installing ATS. It too is permitted to travel up to 90mph.
UP did not install any such control system, thus the maximum speed any of their trains could travel at was and is 79.
UP had (has?) hundreds of miles of main line with cab signals, and much of it was 90 mph timetable limit for passenger trains. The 90 mph limit west of Laramie lasted … into the 1980s?
Of course. How stupid on my part. I completely forgot cabsignals qualified under the 1947 act. So yes UP could exceed 79mph over many portions of their mainline. Guess that shoots my hypotheses why they stopped running fast freights.
I wonder if UP cab signaling is still in operation over any portions. If it was removed, then that might be why the speeds reduced.
Based of the fact that 844 and 3985 still have operable cab signals, I’m guessing they’re still in operation on at least some of the UP system.
Maybe some of our UP forum members can provide a more complete answer.
I have no doubt that the UP dumped the high speed freight gearing because there is no economic justification for running surface freight that fast.
If it’s that critical, as in “I forgot to buy mom a Christmas present and I’ve just got to get this there by the 24th” or “These dresses will be out of season if we don’t get them in the Target DCs by the 1st”, it can go in an aircraft. If it’s normal freight (including perishables such as lettuce) 60/70 MPH top end is about as fast as can be justified.
High speed freight cost money, and it usually just ain’t worth it.
A classic example was Sea-Land’s SL-7 class container ships. Sea-Land’s founder, Malcom McLean, is often cited as the founder of containerization. I’ll disagree. He was certainly one of the founders, but not “The Founder”. In any event, he got the whole container thing right. But his next big decision was a disaster.
He wanted speed on the surface so he caused a fleet of eight fast container ships to be constructed. These were the SL-7s. They could cruise at 33 knots, or 38 MPH. That may not sound fast, but it is. A ship makes its speed by moving consistantly at that speed. It does not have to stop as a train does. These ships could move over 900 miles a day; and that’s more than a truck on the Interstate can do legally with a single driver. They could have raced the QE2 but Sea-Land saw no benifit in disgracing the passenger liner.
They were hopelessly uneconomic and Sea-Land found itself with eight new ships that couldn’t earn a dime. To get to that speed the ships had to have 120,000 HP. The only engines that could deliver that HP were steam turbines. Boiling the water to create the steam used fuel excessively. Large diesel engines were more fuel efficient, but they couldn’t driv
As I’ve told before and elsewhere, an engineer friend of mine once said to me when I showed dismay at a 35 mph speed limit on a line he worked, “you’d be surprised at how far you can go in an hour at 35 mph.” And he was right, of course, as long as it was a consitant, constant movement. Though I do think Americans are overly interested in speed, just for the wrong reasons and in the wrong way. To go fast just to go fast is wrong. But to be able to go fast to deliver better product is ok. The market makes up your mind.
Henry6: You are right about fast just to go fast. As tree stated the steady run is very important. HSR is an example. A 30 mile segment at 120MPH will take 15 minutes. A 30 mile 120 MPH segment with a 1 mile 30 MPH segment will take about 20 minutes including acceleration and deceleration. 90 MPH over the whole 30 Mile segment takes 20 minutes. So which is cheaper making a whole segment 120 MPH except the 1 mile or going to 90 MPH the whole 30 miles?
So if the 855 miles of Auto Train could be operated at its 70 MPH max speed with no slow orders would take 12.2 hrs. Add acceleration and deceleration at the terminals and Florence 1/2 Hr service stop. 13 hours end to end. (I know how do you get the freights out of the way?). Would start up costs be less to get the 79 MPH trackage than building the separate HSR line that would start at 90 MPH but have the same slow orders?.
If a train is running empties and goes more than 60mph they tend to derail, especially the back end of the train. [#dots] That’s my [2c]
Uh, about 35 miles. But I could be wrong. I tried, but I couldn’t stop myself.
These trips mostly likely happened before event recorders were as prevalent as today. Apparently you could get a lot of work done back then. Just make sure you have the proper running times on the delay report…[;)]
Empty roller bearing cars might saw through the bearing adapters at higher speeds, but apparently the older plain bearing cars could handle it. Had some side play in the journal boxes to help out.
Cab signals are alive and well on the UP.
Off the top of my head, there is the ex-CNW Automatic Train Control with two aspect cab signal across Illinois and Iowa. Four aspect Coded Cab Signal from Omaha to Utah, Kansas City to Gibbon Jct and a few other lines or parts of lines.
Jeff