The answer to this question may very well be, I am just too much of an amature to ever properly grasp this question. But:
I grew up along the former Wabash in Souther Illinois (Decatur to St. Louis). That line has always had a reputation as a bit of a race track. As there is a long stretch of highway that goes along side the track near my home town of Mt. Olive, I have had ample opportunity to clock the speed of freight trians.
Road railers regularly run at 65 mph and probably average 55 mph. Most manifest freights average 50 mph but I have seen 60–and on very rare occassions 65. 67 mph was the record, but that was about 15 years ago.
Anyway, I have walked that line 1000 times and am familiar with rail lines around here (Indiana) that are only rated for 40 mph. For the life of me, I cannot determine the difference between the Wabash main of a 65 mph speed limit and some of the 40 mph track I see around Indiana. In many instances (INRD being a good example) the rail head is actually heavier on the INRD than it is on the Wabash. I am fairly certain the Wabash rail head is 120 lbs, whereas much of the INRD is 136 lbs (also largely welded).
To further complicate the picture, I was reading a book about a shortline that bought the old Erie main in Northern Indiana. That line was rated at 110 mph! according to a book about the INRD (this was back in the late 70s-early 80s). Surely, given the neglect of the Erie, it could not have been in better shape than the current INRD?
Also, there are a lot of old ties on the Wabash main. The Wabash main seems to have some more ballast, but not what I would think would be a noticeable difference. Finally, if the curves on the old Wabash main are super-elevated, it is lost on me.
What is the difference between rail rated at 40 mph and rail rated at 65 mph.
The main difference is how often the track must be inspected. The faster the max authorized speed, the more often the track must be inspected.
Rail weight, ballast depth, and tie spacing are also factors.
In addition, higher speeds are tougher on the track. While physically the track may be able to handle 65 mph trains, the railroad may limit the speed to 40 mph to ease the maintance burden.
Could a higher speed limit be employed on a specific route to increase the line’s capacity to move traffic? (higher speed allows more “throughput” per hour)?
Yes, and it’s done, but not without a lot of due diligence and long thought because (a) there are usually heavy costs involved to upgrade the track structure, (b) it has to be certain that the increase in speed limits will actually be realized and not lost in terminal delays and meets, (c) that the economic payoff makes the investment more profitable than, say, U.S. Treasury bonds. At some point the line becomes limited by curvature, and the economic cost to reduce curvature is usually prohibitive with the exception of a few key bottlenecks, e.g., the tight curves at Vicksburg, Miss., on KCS.
There are numerous recent examples of this sort of process:
UP (ex-SP/RI) Golden State Route, El Paso, Texas to Topeka, Kansas
UP (ex-MP, ex-TP), Fort Worth to El Paso, Texas
UP (ex-KP), Topeka, Kansas to Denver, Colo.
BNSF (ex-Frisco), Avard, Okla., to Enid, Okla.
KCS (ex-MidSouth, ex-IC), Meridian, Miss., to Bossier City, La.
As you can see these are lines that either fell on hard times due to decline in traffic or decline in the financial health of the owner, or lines that were of little strategic value historically that gained value due to changes in traffic patterns and the results of mergers. In none of these cases were there significant alignment changes; the work consisted of out-of-face rail, tie, and ballast replacement; replacement or installation of signaling; and siding extension and installation.
There is a big cost difference in making a track upgraded for higher speeds.We had some 50mph crossovers replaced here on the Kenova District (NS),and they dropped the speeds to 40mph.I asked a MOW boss why they done that .He told me that upgrading the crossovers to the 50mph limit would have cost $17,000.00 more .Where he got the figure,I haven’t a clue.And one other thing that the railroads done was take the “lift” or “elevation” (where one rail is higher than the other) out of the track.I was told the rail doesn’t wear as bad when the track has the “lift” taken out.[:)]
I guess it is kinda like comparing a high maintennce woman to a high speed railroad…both costs lots of $$$. Is it worth it? Only the person financing can tell.
the prose does have a very familiar ring to it, doesn’t it? Hmm…
There is one point to be noted in the 40 vs. 55 – the forces on everything are doubled at 55 over 40. Twice as far to stop. Twice as much impact on the rail. Twice as much lateral force on curves. etc. No wonder the increased speed takes much more maintenance!
I think that the Erie, during its last days, had freight speeds of 40 MPH for manifest freight and 50 MPH for piggyback freight such as the NY-99’s. This was the case west of Marion, to the best of my knowledge.