Trackbed Maintenance Question

[Anonymous]

Have a question for anyone knowledgable about trackbed maintenance, specifically as it pertains to in and around paved gradecrossings. I've noticed at several of the local grade crossings on the CSX (ex B&O) main through town that there appears to be a significant dip or give in the rails in the short distance, maybe 10 feet or less, on either side of the grade crossing when a train is passing over. It would seem that the engine crews would feel a sensation similiar to going over a bump at these locations. Everything looks OK and level when there are no trains. It seems to me this condition could be relieved by placing extra ballast underneath the tracks in these areas. Is this play normal or desired for some engineering reason? Is there an accepted tolerance for this condition? I've seen enough of a jump that it is not inconcievable to be that this condition could cause a derailment, expecially on some of the faster traveling freights or Amtrak's Capiol Limited.

[mudchicken]

Get rid of the road crossing and the dips go away. Change in track modulus (stiffness of the rail ties ballast and sub-ballast changes when you hit a fixed object. The dynamic track structure has nowhere to spread out the force (weight and wheel impact load) so the track structure takes it out on the weakest element of the track structure, the ballast and sub-ballast. Mechanical action forces these two elements down and they stay down causing the dips & ballast pockets. The roadmaster and his track gang eventually come out and add ballast/tamp to correct the problem. If they don't, Mookie gets after them.

The only place asphalt belongs is under the ballast! [;)][;)][;)]

[kenneo]

MC

How do what appears to be steel reinforced concrete slabs do as road crossing material. Asphalt always been really bad surface for crossings and very much worse for street running. Wood planks, as troublesome as they are, have always been better. So has been gravel.

[mudchicken]

Less forgiving....if there are timber ties under the concrete x-ing planks, you get splinters and wobbly field side planks. Concrete gives you mudholes and rubber dust from the remains of the adze-pads, plus the ballast degrades quickly.

[kenneo]

QUOTE: Originally posted by mudchicken

Less forgiving....if there are timber ties under the concrete x-ing planks, you get splinters and wobbly field side planks. Concrete gives you mudholes and rubber dust from the remains of the adze-pads, plus the ballast degrades quickly.

They sure are putting a lot of them in around here on the ODOT owned parts of the P&W. Using (about) 130 lb rail on wood ties with Pandrel spikes. They are holding up much better than the rubber crossings.