> To prevent this, a big part of railway maintenance involves digging out all the stones, washing them to get rid of sand and soil, and putting them back.
This is called "ballast cleaning" if anyone wants to do a search:
- Removing the ballast from a section at a time to do the cleaning means that the rails and sleepers are floating in the air (~1:30 to 2:35)
- They're doing all this work, including transferring waste to another train, underneath catenary wires. low clearance!! (3:40 to 5:20)
Also important to note, they aren't so much washing the stones (though that may be part of the process), they're sieving (grading) the stones to remove everything that's under a specific size (looks like they're removing everything that passes a ~25mm/1" sieve, but scale in a video can be deceiving). Rail ballast is very uniformly graded, i.e. every piece of aggregate is about the same size. Vibrations over time will cause edges of the stones to chip and wear down, with these chips contaminating the ballast. It also leads to rounding of the aggregate, so there's less interlock between the particles.
I'd never considered how much "it helps to have rail, to replace rail" impacted the process -- but it makes sense as everything is incredibly heavy! (Rails, sleepers, aggregate)
From that perspective, of course you'd excavate and clean the track ballast while you're also on the same track. And same with sleeper and track replacement.
We don't see any tank wagons, and there would be no other possible water supply, so I don't think they are washing the stones. Given it gets rained on anyway, I doubt there would much benefit.
I don't know much about the earliest car roadways, do you have a link with some info?
Granular gradation is still a major part of modern roadway construction, there are just certain standards that are very typical so they get used without too much thought required. For some applications a visual inspection is enough, but there's generally some standard proportion of sieve analysis required (eg. 1 test per 10000tonne produced), along with proctor tests (to determine maximum dry density) and frequent nuclear densitometry. I've even seen loads of aggregate get rejected due to the large aggregate being too oblongated.
When you get into concrete or asphalt mix design, the aggregate standards can be even more strict - chemical makeup of the stone can be important to avoid alkali-silica reaction; minimizing fines increases the strength of asphalt mix but creates a tougher riding surface; etc etc etc.
The next video in my feed explained a more complete rehab, including replacement of the sleepers (ties) and rails while allowing the adjacent track to stay in service. F’n amazing.
Unreal. I was stood on the platform two days ago wondering why tracks have ballast and how it was kept so clean, and today I'm watching the most incredible process and machinery that answers my question. I have a totally new respect for train tracks now.
I worked for different parts of the national railway company of my country (France) for four years (circulations management and scheduling mostly - briefly on a CBTC system and the first studies on autonomous driving). It’s hard to understand how complicated it is to keep trains running if you haven’t experienced it.
Aviation and Space has a lot of challenges, but also a lot of flexibility.
Planes, for example, can share the same geographic location -- just at different altitudes; e.g. 25000 ft vs 33000 ft vs 45000 ft., etc. After a certain altitude there isn't anything. No clouds, no birds, just air; set your auto-pilot and go. Takeoff and Landing can be hairy, and you gotta worry about mountains, but that's about it. A basic radar makes it easy to see, and not hard to broadcast by radio.
Same basic idea for space. Gotta get out of orbit and not get cooked by radiation, but otherwise there is a whole lotta empty, and it's not hard to see what's going on with things like radar.
On the ground it ain't so simple. Someone stuck on a rail, avalances, bridge collapses, hills vs inclines, snow / ice / rain / high-winds, and no ability to multiplex, so scheduling gets even harder since there are only so many ways into or out of a location. Trains full of high explosives or toxic chems drive right through downtown areas, often multiple times a day. From a crime and security perspective, airports are locked down pretty hard, while most people could probably just drive to a siding near them and fuck around; you can derail a train with a $400 block of steel you can order online. Communication and signal loss is also way more complicated, esp. if you're going through a mountainous or remote area.
Yikes, that guy just sitting underneath the moving gantry loaded with tons of sleepers... And then the other fellow crawling in between the wheels of the whole machine _while it is moving_... Do they not have something like OSHA wherever this was filmed??
Also, disappointing they didn't actually show the new railstock being laid, just the ballast and sleepers :/
That's a quality job. I've been in a station when a Caltrain ballast replacement train came through. Caltrain just had a hopper car full of ballast rock dumping on new rock. A railroad tie was being pushed by the wheels of the hopper car to smooth the ballast. I was amazed that didn't result in derailing the hopper car. It was really low rent. I assume they followed up with a ballast tamper at some point, but it wasn't part of the ballast dump train.
Caltrain outsources much of their maintenance of way work, and it shows.
Here's a video of that operation.[1] Yes, they really did level the ballast by putting a spare railroad tie ahead of the wheels of the hopper car. This was before the upgrade to concrete ties.
That was 23 years ago, but still looks low-rent. Here's how Brightline & the Florida East Coast Railroad are doing it in Florida for their double-track (mostly) expansion to Orlando.
Note that the ballast hoppers have a solar panel on them to charge a battery, which runs a motor to actuate the hopper doors. Much better than a couple of guys with a wrench.
"Here is 1000 miles of railway. Each yard of that railway has 1000 lbs of crushed rock under it. Your job is to pick it all up, put it through this sieve, and put it back. I will employ you for $1 a month for 50 years to get the job done. Do we have a deal?"
No-one asked, but ... I worked at a power station one Summer, my job was to clean the filters at the bottom of the cooling tower. The filter was a stack of plastic bricks; each brick about 1m x 1m x 2m that were a mesh of orthogonal perforated plastic panels with a spacing of maybe 8cm or so. The filter was stacked about 5 "bricks" deep. We washed the bricks under a running hose of about 20cm diameter, standing in water all day; shaking out the mud. The bricks were heavy because they were full of what seemed like river mud. The detritus from the bricks fell down into the pond below the cooling tower, about 20m beneath us. Small skid-steer cat loaders dug out the pond.
I had a runner's build and was being paid £2.70 an hour (late 1990s); the other guys had weight-lifter builds and were on >£10 (they travelled around the country doing the same job, there wage was good money for low-skilled work at the time). I found out that the agency were being paid about £10 for me ... stood in dirty water all day, with the fall risk, the low wage, ... wasn't great. Then I had to quit because of injury after a few weeks. Knee was never the same.
That's not a filter, that's structured packing to give the water a large surface area to evaporate from.
Or possibly used as a drop catcher with spray nozzles underneath; either way the gas stream hits the surface without excess wasteful turbulence.
The workers seem to be wearing the amount of PPE that I'd want if I was just walking along downwind, but nowhere near the amount I'd want if I was working in the thick of things 8 hours a day. I wonder what their lung disease rates are like.
The ones I see are wearing N-95 masks or equivalent. I'm no expert, but based on what I've learned since early 2020 I'd say that's plenty, provided they only use them for one day and toss them out.
Steam locomotives, at least, used total loss lubrication. Their brakes were made of asbestos. And a good preservative for railroad ties was creosote. Never mind the stuff they spray to keep vegetation at bay. So even I would probably be wanting to wear an N95 mask if exposed to dust from that stuff all day.
In this case it's a high speed line which will never have seen a steam locomotive, and where most trains will use dynamic braking (returning the power to the electricity grid, or else dumping it into resistors).
This is called "ballast cleaning" if anyone wants to do a search:
* https://www.youtube.com/watch?v=zNFUgTJR6jw
* https://en.wikipedia.org/wiki/Ballast_cleaner