A New York railroad uses lasers to stay on schedule | Hacker News Reader

A New York railroad uses lasers to stay on schedule

thedrive.com

108 pointstomohawk48 comments

This is not new tech. Lasers have been cleaning rails in Europe for years, mabey a decade or more. If anything, this is only new in the US. It is not unproven tech and those involved are being disingenuous in describing it as so.

2002

https://www.laserfocusworld.com/fiber-optics/article/1655239...

https://www.youtube.com/watch?v=Kh6U4QJmutA

"all thanks to pioneering laser technology that most railroads are too scared to try out."

No. Most railroads are not scared of lasers. Those with the business case for this tech use it. Those without do not. Maybe "most" American railroads don't use these things but the reasons behind that are probably more political than fear-based.

From 2014:

"North American freight railroads, in general, have accepted the degraded performance debris can cause. Most of the current solutions are not efficient for the amount of territory and service required. A road vehicle with rail wheels based cleaning system would be most useful, allowing one or two workers to concentrate on the worst locations and move between trouble spots quickly.

- Steven Belforti, Guilford Rail System"

https://www.newscientist.com/article/mg22429984-800-locked-o...

Anyone who lives on Long Island or takes the LIRR will let out a bitter laugh at this article.

> 90.7 percent of trains were on time in November, an improvement of 3.8 percent over last year

The metrics used by the LIRR were so disconnected from reality that the state actually passed a law this year mandating that they had to adopt meaningful standards.

https://www.newsday.com/long-island/transportation/mta-lirr-...

The entire LIRR system is plagued by cancellations and delays on a daily basis. There's nothing quite like standing on the train platform looking at the little digital sign that says, "the 7:08 to PENN is on time" while you look at your phone and see its 7:25 and the train is still nowhere in sight.

https://twitter.com/LIRR

Would be cool if they could blast a cloud of heat whenever going over a switch.

There are lots of remote switches that just have a big propane tank to keep them clear of ice.

Because switching shakes the train around, sometimes a block of ice from an ice storm 1000km away can dislodge and jam a switch until it’s clear or melts away.

>There are lots of remote switches that just have a big propane tank to keep them clear of ice.

Except the switch has to be in the correct position first to get a train over it. The rail lines in NY including the subway just use natural gas heaters on most switches.

In much of Europe electric heaters are used in much the same way. The American practice of using natural gas heaters always seems… crazy to many of us. (Especially in areas where there's already electrical supply!)

Electric makes sense if you've got a good clean source of power like nuclear, solar or wind. But if you're getting power by burning fossil fuels then it seems more efficient to use that heat directly rather than to use the heat to generate steam to turn a turbine to turn a generator to produce electricity, and then turn that electricity back into heat again.

For indoor heating, sure, but these are outdoor switches.

Propane/natural gas switch heating is like sitting in-front of a campfire, while electric would be like having a heating pad on your skin.

Or maybe the electric ones are just blowers too with one central heating point and a bunch of vents. Dunno.

Some of the electric heaters are blowers (https://www.rwy.com/products-rwy/track-heaters-accessories/e...) while others use heating elements in direct contact with the tracks (https://spectruminfrared.com/railroad-products-and-track-swi...).

I suspect any of these mechanisms, however they work, are going to be wildly inefficient. The very premise of melting ice outside in the winter on big pieces of metal exposed to the elements seems like a huge energy sink. Whether electric heating is sufficiently more efficient to offset the inefficiencies in power generation and transmission I couldn't say, but it's far from clear to me that the 'American method' of using propane is crazy.

Electric heating pad and tape usually have a pretty short lifespan; the kind you might get to prevent ice dams on old, poorly insulated eaves / roofs might maybe last 5 years if you have cold winters.

Higher grade industrial elements might last longer, but nat. gas is going to be significantly more cost effective in the US

Gas heated switches were common in Europe too. Operators switched not for cost or environmental reasons but ease of operation.

Gas is cheap in America and it's not like Russia can flip a switch and make us shiver.

Heating with fossil fuels is a lot more efficient than heating with electricity made from fossil fuels. Power plants have an efficiency of at most 60%, the rest is wasted heating the plant. Burning the fuel on-site converts 100% to heat where it's needed.

That would only be possible if the fumes come out at environment temperature.

Right, I forgot about that. Nevertheless the efficiency is a lot higher.

The European practice of using Russian natural gas at all while they are literally using that money to attack and annex other European countries seems crazy to us.

They’d rather not think about it.

Same in Chicago with Metra commuter rail, still lots of switching issues in the winter. Hard problem to solve, even with the liberal application of heat.

One of my favorite sights when I was commuting into Chicago - seeing a large section of switches a little North West of Oglivie lit on fire. I presume they use kerosene.

You may enjoy this: https://www.youtube.com/watch?v=z76ywZDXyPw

Wonder why they can't add these roof-scraping systems that semi trucks use: https://media2.giphy.com/media/Vrg6gYOK0AO6A/giphy.gif (on a long straight bit)

For dry leaves this would be fine I’m sure, but the problem is wet leaves which essentially turn to slime that would just be spread along the track by a system like that. If you’re in a locale where leaves fall in the autumn, next time you’re out on after a rainy day find some half decomposed leaves around a puddle and you’ll see. They break apart into a very slippery goo.

That test rig in the video looks like a low-tech electro-mechanical Dieselpunk version of SG-1!

Seems like they found a kickstarter promoter to do their video.

I noticed they needed eye protection in the lab.

I'd love to see how they avoid needing eye protection for people near the train tracks in the field (presumably some shielding and very careful laser alignment?).

I'd be particularly interested in whether the lasers are safe on overhead tracks near populated areas (certain MTA lines in New York are like this).

I imagine the laser undergoes significant decoherence in practice.

No one is doing quantum leaf removal. I think you mean dispersion.

Elevated tracks probably don’t have much of a problem with leaves falling on them due to their height. The NYCT does presently use “gel” trains on on-ground tracks, but I’ve no idea if they use them on elevated tracks.

There is a video about laser rust removal which is quite amazing. It doesn't even seem to hurt flesh as the operator intentionally runs it over their hand, around the 1 minute mark:

https://www.youtube.com/watch?v=ACGSzBXKONo

That’s amazing! Now if only there was something like this wood surfaces, I’d have a blast (no pun intended) working on my boat then!

Why don't they just put a leaf blower on the front of the train? Maybe a dumb question. Could be due to stuck wet leaves?

The leaves are often partially decomposed into a sticky slime that end up compressed to the tracks from what I’ve read elsewhere.

This. Actual dry leaves that can be blown off really aren't the trouble, it's wet ones that quickly turn into sludge and just get compressed into slicker and slicker slime that provides no traction.

The current solution in most of the world is essentially high-pressure jets of water to clean the rail; obviously you eventually reach a point where you don't have enough pressure to dislodge the goop.

What about a nylon brush?

My non-engineer guess is that a nylon brush would be shaved down pretty quickly by rail contact at typical train speeds, so that it would be ineffective at removing debris after a very short time.

Plus I imagine it'll apply nowhere near as much pressure on the track, so you'd end up needing a lot of brushes and then they'd all be wearing down quickly at 60mph or so.

The current system is to put sand on the rails for added traction.

Most places don't use sand alone to treat the rails after cleaning them, and haven't for a long time.

Sandite is used in many places, which essentially adds some sort of metal shot and antifreeze to the sand. The goal is essentially that this mixture will be interspersed with the leaf gunge that accumulates over the day and both provides better traction (sand, antifreeze) and helps any track circuits to continue to function even when the tyres are unable to make direct contact with the rail (metal shot).

Despite what others said about it wearing down, it’d also get clogged up pretty quickly. Otherwise you could potentially use something with more durability, like a steel bristled brush.

So the thing is, the leaves are only the problem insofar as they are the source of the oil. The leaves are pressed between wheel and rail and leave a film of oil, which a steel or nylon brush isn’t going to clear.

Yes, if you get the leaves off the rails, there should never be any oil, but if some slip by your back where you started.

Not as cool

Ah, thanks for the insight. Someone had to ask :)

It’s amazing that this isn’t a fire risk. In California they turn off the electricity when the wind blows during the dry season, and in NE we fire freaking laser beams at the leaves to eviscerate them.

The New York trains I remember would make sparks all the time; I would suggest any dry tinder near the tracks would be a risk either way.

California has electrical wires entangled with dry trees after years of drought. (Trees are tricky, since it takes years after installation for them to grow tall enough to reach the power lines. In the NE I've seen power outages caused by tree branches laden with ice from freezing rain sever power lines.)

Why don't the same crews who rake the forests also rake the train tracks? ;)

Most places aren't nearly as flammable as California. Where I grew up people don't think twice about making a camp fire, but apparently that seems next to inconceivable to some people in California. Hell, many places have too much fresh water, not too little. "Dry season" isn't even a concept in many parts of the world.

The LIRR doesn't run in areas conducive to catching fire. They literally use open flames to defrost the rails when it gets cold.

https://media.wired.com/photos/5932717eb8eb31692072f8f8/mast...

The east coast doesn't have a "dry season" in any sense California would recognize. If it did this system might not be needed: it sounds like the problem is wet leaves being compressed into lubricant slime where dry leaves would just be crushed to powder.

This seems like a Great idea.

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