09-21-2017, 10:15 PM
Concrete is essentially rigid, which is great when you have a (relativley) lightweight vehicle on it. It doesn't need to flex.
A freight train, however, is very heavy. The tracks actually flex under the weight of the train as it rolls over. So too does the pavement.
Embedding tracks that would be suitable for a freight train to go over would require an astronomical amount of concrete. I can't think of anywhere where I've seen that done. It's just not an industry standard at all. This is why all the rail crossings along the spur lines use deck plates with the ballasted track continuing underneath, not embedded track.
You can rip up the pavement pretty easily and re-tamp, too - and then lay down more pavement over top. That can be done quickly and economically - like re-doing some drywall. It may appear like a lot of work, but it's actually pretty cheap, and all the tools are in place to handle it.
Another point is the transitions - going from ballasted to embedded (or back) is very tricky. Even for the LRVs, there's a complex foundation under the ballast that steps up, shallowing the ballast as it approaches the fully embedded section. If they didn't have that, there would be a very difficult to maintain transition between the "Spongy" ballasted track and the "rigid" embedded track. The significantly higher mass of a freight train would pummel that into a massive speed bump in no time.
A freight train, however, is very heavy. The tracks actually flex under the weight of the train as it rolls over. So too does the pavement.
Embedding tracks that would be suitable for a freight train to go over would require an astronomical amount of concrete. I can't think of anywhere where I've seen that done. It's just not an industry standard at all. This is why all the rail crossings along the spur lines use deck plates with the ballasted track continuing underneath, not embedded track.
You can rip up the pavement pretty easily and re-tamp, too - and then lay down more pavement over top. That can be done quickly and economically - like re-doing some drywall. It may appear like a lot of work, but it's actually pretty cheap, and all the tools are in place to handle it.
Another point is the transitions - going from ballasted to embedded (or back) is very tricky. Even for the LRVs, there's a complex foundation under the ballast that steps up, shallowing the ballast as it approaches the fully embedded section. If they didn't have that, there would be a very difficult to maintain transition between the "Spongy" ballasted track and the "rigid" embedded track. The significantly higher mass of a freight train would pummel that into a massive speed bump in no time.