This method has some merit. A spot can be fixed in 12 hours + replace any bad ties while the subgrade is being mitigated. Appears not as many personnel needed. Also, workers can stay from active tracks more often. Watch the link in the article to see the whole operation.
DavRail: Mud Spot Remediation Completed in Record Time - Railway Track and Structures
I watched the video and I understand this is to save labor due to automation but what exacly are all those folks on the higher elevated track doingâŚexactly?
Not impressed by the video.
Youâre looking at a few things here. The equipment is operated on adjustable caterpillar treads clear of the track, so longer âpanelsâ of track can be lifted at one time (here, just twice as long as â39ââ jointed rail panels). Apparently what they seem to be saying is that each lifted panel is carried back a la Rcrane to where a bunch of ties and OTM are pre-positioned so the existing ties drop in between, allowing the panel remediation to be made during the time the ballast and subgrade are being restructured, cement-injected, or whatever to get rid of the chronic wet spot. I sorta assumed that the old ties were left in place until the new ones were spiked or clipped in place, to maintain geometry. The panels are then lifted and run back, and conventional track alignment and field welding done to complete the job.
In theory you could do top-down alignment with a rig like this, but it would require more consistent vertical adjustment precision than I see provided here.
The idea that you would have to cut the track into 39â sections without this equipment is absurd. How long a piece of track you can pick up and move is not a function of what kind of equipment you use - as long as it is something that can hold the load while moving in the desired direction - itâs how many pieces of the equipment are home hooked up. Excavators (track hoes) are nice because they can move in any direction. Sideboom cranes work great if youâre going to move the track section longitudinally, which is also where you would use the Davrail centerlift system, and derailment contractors keep scads of those on standby anyways. Front-end loaders work fine too, if youâre moving the disconnected track sideways.
As an example, we had a subgrade remediation project not unlike the one shown in the video last fall, except the problem area was longer and deeper. A derailment contractor had no problem picking up a 400â track section in a single piece and moving it longitudinally down the track out of the way, and then bringing it back 18 hours later. Took about 30 - 45 minutes for each move, out of a 28-hour window. Mostly sidebooms, a couple excavators at the ends.
The big advantage that I see for the Davrail system is where you have no access along the side of the track for equipment, such as if youâre working on a steep fill or on the middle of three tracks. But those projects are still going to be challenging for other reasons (like getting material in and out) and you may need to build access anyways.
For lifting low-quality track with cut spikes, like what was shown in the video, the Davrail equipment has one other advantage: it is less likely to twist the track as it lifts or moves it. Cut spikes put off relatively little torsional resistance (i.e. the donât keep the track from twisting around an access running down the centerline of the track), which is fine because thatâs not something that happens in regular service. If the wood has lost its ability to hold the spikes, then you can get into a bad situation where a.) a big portion of the ties simply fall off when you lift the track panel, as shown in the video, which b.) makes the track even flimsier so that c.) any twisting action can cause even more of the ties to fall off. The center lift could help prevent part (c) of that sequence by minimizing twisting.
Or, you can go through and replace the worst ties and double-spike the rest BEFORE the day of the big window. (Thatâs also what you should do before a production undercutter comes through.)
Dan