The difference between 40 mph and 55 mph?

[gabe]

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.

Gabe

[nbrodar]

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.  

Nick

[CNW 6000]

The difference is 15 mph.

[eolafan]

The difference is 15 mph.

Ha, Ha, Jolly Joker!

[Anonymous]

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.

Gabe

Some of the factors that determine train speed:

1.  Method of operation.  FRA regulations require a block system of operation (manual or automatic) to exceed 49 mph for freight, 59 mph for passenger.  (Note -- you do not have to have signals, as is commonly assumed, to go faster than 49 mph, just a block operation per 49 CFR 236.0.  KCS, for instance allows 55 mph in dark territory on the L&A between Meridian, Miss., and Bossier City, La., because it uses manual block).

2.  Track class.  FRA permits 40 mph (freight) for Class III, 60 mph (freight) for Class IV, 80 mph (freight) for Class V.  The differences between class is how much money you want to spend.  Higher speeds have less tolerance for wide gauge, deviation from alignment, cross-level variation, runoff (variation from vertical alighnment), and condition of ties, ballast, rail, joint bars, and turnouts.  Size of rail is not prescribed.  A very good "users manual of track" is found at http://www.fra.dot.gov/downloads/safety/track_compliance_manual/TCM%205.PDF (143 pages, beware).

4.  Rail weight is something that goes hand-in-hand with high average axle loads and high gross ton-miles, not so much high speeds.  115-lb rail is perfectly good for high speeds.

3.  How fast do you really need to go?  Higher speeds require more fuel and greater expense for track and rolling stock maintenance.  For many lanes and types of freight higher speeds diminish profits.  There is no point in racing to the interchange and arriving at 1700 instead of 1800 if the connecting railroad only picks up once a day at 2400.  Chasing minutes out of the system is very hard because it is a "tail wagging the dog" type of iteration that tries to bend the performance of the entire system to the performance of a single element.

Railroads spend a lot of management time choosing the speed that gives the best results (profit) for the traffic mix given limitations on capital expenditure, demands for profits by the shareholders, etc.  As for historic cases, axle loadings were generally much lighter, labor costs were much lower, and passenger service demanded higher speeds.  In some cases track capacity and train-speed conflict difficulties mandated higher speeds for freight, too.  I do not have the book in question that you recall saying the ex-Erie main line in northern Indiana was still good for 110 mph in the 1980s and am skeptical that was indeed what the track was still good for.  Given the sketchy nature of that "fact" I would set it aside.

S. Hadid

[gabe]

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.

Gabe

Some of the factors that determine train speed:

1.  Method of operation.  FRA regulations require a block system of operation (manual or automatic) to exceed 49 mph for freight, 59 mph for passenger.  (Note -- you do not have to have signals, as is commonly assumed, to go faster than 49 mph, just a block operation per 49 CFR 236.0.  KCS, for instance allows 55 mph in dark territory on the L&A between Meridian, Miss., and Bossier City, La., because it uses manual block).

2.  Track class.  FRA permits 40 mph (freight) for Class III, 60 mph (freight) for Class IV, 80 mph (freight) for Class V.  The differences between class is how much money you want to spend.  Higher speeds have less tolerance for wide gauge, deviation from alignment, cross-level variation, runoff (variation from vertical alighnment), and condition of ties, ballast, rail, joint bars, and turnouts.  Size of rail is not prescribed.  A very good "users manual of track" is found at http://www.fra.dot.gov/downloads/safety/track_compliance_manual/TCM%205.PDF (143 pages, beware).

4.  Rail weight is something that goes hand-in-hand with high average axle loads and high gross ton-miles, not so much high speeds.  115-lb rail is perfectly good for high speeds.

3.  How fast do you really need to go?  Higher speeds require more fuel and greater expense for track and rolling stock maintenance.  For many lanes and types of freight higher speeds diminish profits.  There is no point in racing to the interchange and arriving at 1700 instead of 1800 if the connecting railroad only picks up once a day at 2400.  Chasing minutes out of the system is very hard because it is a "tail wagging the dog" type of iteration that tries to bend the performance of the entire system to the performance of a single element.

Railroads spend a lot of management time choosing the speed that gives the best results (profit) for the traffic mix given limitations on capital expenditure, demands for profits by the shareholders, etc.  As for historic cases, axle loadings were generally much lighter, labor costs were much lower, and passenger service demanded higher speeds.  In some cases track capacity and train-speed conflict difficulties mandated higher speeds for freight, too.  I do not have the book in question that you recall saying the ex-Erie main line in northern Indiana was still good for 110 mph in the 1980s and am skeptical that was indeed what the track was still good for.  Given the sketchy nature of that "fact" I would set it aside.

S. Hadid

I am sensing the presence of a powerful force that I have not felt in some time . . .

As for the book, it is the "Indiana Rail Road," in the section about Tom Hoback's employment history preceeding his purchase of the INRD.

Thank you for the very learned response.

Gabe

[jclass]

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)? 

[Anonymous]

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.

S. Hadid

[MP173]

Gabe:

I agree with your perception.

ed

[mackb4]

 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.

[MP173]

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.

ed

[jchnhtfd]

Gabe:

I agree with your perception.

ed

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!

[nanaimo73]

Gabe:

I agree with your perception.
 

the prose does have a very familiar ring to it, doesn't it?  Hmm...

I mentioned that to Chad two weeks ago, and he sent an email "over there" and got a no for an answer.

[timz]

That [Erie] line was rated at 110 mph!

By whom?

[ValleyX]

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.