In urban industrial areas I often see long stretches of tracks paved over with blacktop - exactly in the same manner as a grade crossing, but over much longer distances. This is common in alleys between buildings, at team tracks, loading docks, and so on.
My question is, does the black top over the track help preserve it, and thus make it last longer? Or, does track in this situation actually deteriorate faster than otherwise due to trapped rainwater under the pavement unable to evaporate quickly.
This is a matter I always ponder when I see old rail embedded in pavement. Has anyone here ever maintained a street railway by any chance?
I do not know the answer to your question, but to add to it: I have always wondered how blacktop-concrete right of ways withstood the movement of heavy freights.
When you are at a crossing watching a heavy train go by and look at the ties, there is quite a bit of up and down movement compared to when the car’s trucks are on top of a tie as compared to when they are not. I would think this would tear blacktop to shreds.
I am sure there is an obvious explanation as to why this is not the case; I just do not know it.
Gabe
…Railroad tracks are still on top of ties regardless whether passing over a road crossing or not…The ties continue under the rails at the crossings just as on the track at either end, etc…
I could only imagine what tracks on top of concrete or blacktop would do. You’d think the vibration alone would have the concrete crumbled in no time. I remember someone saying a while back in the concrete vs. wood tie debacle that the increase in noise/vibration with concrete ties alone was pretty noticable.
I actually believe that the railroad track doesn’t care what you put on top of it–it’s what’s underneath that counts. Passing trains will cause the track to settle and rise anywhere, and neither blacktop nor concrete paved right next to the tracks will stand up to too much of that. The pre-stressed concrete panels that many modern grade crossings have seem to hold up the best, and that would probably be the way to go for long stretches of tracks-with-pavement as well.
I [:(!]HATE asphalt unless it is under the ballast. That asphalt will considerably shorten the life of the timber ties underneath by holding in moisture. Asphalt also plays heck with fastenings, promotes rail cant and allows material to get wedged under the rail above the tie plates (not good)…
Asphalt does not flex (different section modulus) like track. This causes headaches, especially if either the track or the road surface sees significant tonnage. You can’t maintain & observe the condition of the track covered in asphalt. Maintaining an FRA legal flangeway in that black crap is a big pain in the patootie and gets worse if you introduce sand, ice & snow. Also your rail gets horribly baseworn in those conditions.
Poured concrete around railroads is even dumber. Track structure is dynamic, not rigid. State Highway Departments like Oklahoma’s don’t seem to understand this.
(Please don’t get me started on what I think of highway engineers when they get around railroads[V][V][V])
If at all possible, AVOID paving track under, especially around switches.
You want a signal system to work in that?[(-D][(-D][(-D]
When I was younger, I was visiting Springfield Illinois and got a real treat. The B&O (or C&O/Chessie, I forget, but the engine was B&O) local–which sadly no longer serves the town–was dropping cars off to a lumber yard.
Apparently, the lumber yard hadn’t accepted cars for several years, and the spur that led to the lumber yard was covered in asphault, as the highway department apparently thought the spur was defunct.
After considerable debate as to what to do, the local simply drove over the asphault. It was really cool. Apparently, the weight of the engine was enough to displace the asphault and when it was done, you could see the rail head, although it was very flush with the asphault.
My memory may be scewed a bit, as I was roughly 6 at the time. But it was as much excitement as a 6-yea
Unless, of course, you have a wheel dragging over them…
Still, that one didn’t come out too bad!
I recall a picture in Trains about some new trackage - Kansas City? The photo plainly showed a nicely laid strip of asphalt. I believe they did say that ballast, then track would go on top of it.
I know of a rail joint adjacent to a crossing that takes a beating. Not having seen the crossing installed, I can only imagine that it is more rigid than the roadbed on either side.
I know that bridges, with their rigid foundations, are a problem, too. Have seen the track a such a joint.
As for paving over, I imagine it depends a lot on what’s under - ie, how’s the drainage?
If you have something like an EpFlex rubber boot (standard on NS Asphalt X-ings) on the gage and field side of the rail acting as an interface seal, you have a chance.
http://www.poly-corp.com/transportation.asp
Asphalt or concrete poured up to the rail is just asking for nothing but trouble. Even with the rubber boots/ seal, the asphalt tends to roll-up and not stay smooth requiring asphalt grinding.
Two people mentioned asphalt as a good thing to have under the track ballast. That’s an interesting concept, and it’s got me scratching my head now. I have a hard time imagining how ballast on asphalt stays put since it’s on such a smooth, hard surface with nothing to grab onto. It seems like the pumping action of the track would eventually cause it to get forced out. Any thoughts on how the ballast will stay nice and solid on top of an asphalt foundation? Is an asphalt under-layer a new “best practice” for laying new track?
Thanx.
Around here, most of the bridges have ballast on them. Some wood trestles do not.
There was a Trains Mag article about a year or two ago showing a picture of BNSF laying new track out in the mid-west somwhere and they were laying 8 inches of asphalt as a sub-road bed, (Im not sure if that’s the right term for it) then laying ballast and tracks on top of it. A BNSF foreman mentioned that it was a new trick but had good resluts so far. Mentioned a a better, more stable bed for the ballast and helped with drainage. Also commented that the ballast evenutally gets pressed into the asphalt and helps to hold it all together. They also had a picture showing the whole process.
(1) You are putting down base course asphalt so that 3 1/2" ballast has something to bite into
(2) It very much is best practice, complete with it’s own AREMA citation…Championed by Dr. Rose in the College of Engineering at The University of Kentucky.
I’ve ntoiced the LIRR tracks in Penn Station have the rails fastened directly to the concrete. In addition the NYCTA subway uses an interesting arrangment of ties set in concrete. The Ties have a gaps or about 12 - 18 inceches cut in them an a concrete ditch runs down the center of the tracks.
I also remember seeing photos in “Trains” showing fabric being laid under the ballast. IIRC, it was in a late '70s or early "80s issue. Jay
And just to add a point or two – keep in mind that asphalt is very flexible; to MC’s point 1, that nice sharp ballast is going to dig right in and stay put.
One of the reasons it’s been taken on as a best practice (perhaps the main one) is that the asphalt layer helps keep moisture out of the subgrade, and helps keep the subgrade out of the ballast – it’s almost impervious to water, and is impervious to fine material. Being protected by the ballast, it oxidizes much less quickly than it would in air, and should keep its flexibility and self-sealing capabilites for years.
Another problem I’ve noticed is improper installation of the asphalt in that they dumped it en mass instead of placing it neatly between the ties first and then filling it up to the tops of the rail. A lot of those NS asphalt crossings are failing because of voids between the ties. (it was allowed to “bridge” the ties and not properly compacted.) It’s as bad as or worse than any pothole when that “bridge” collapses.
I believe that was in the Texas Panhandle, not far from Perryton or Canadian. It was part of a doubletracking project, as I recall. [:)]
The new high-speed railway from Munich to Nuremberg, built for speeds of up to 180 mph, uses concrete ties in a concrete roadbed. It supposedly holds up to stress much better than traditional ballast and tie roadbed. It is also supposedly much quieter. As for maintenance of track in streets, the light rail in many German cities is bolted to concrete ties in a ballasted roadbed, covered with sand and cobblestones between the rails. Asphalt is laid on the outsides of the rail, right up to and even with the railhead. These tracks require frequent maintenance.