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Comment by kposehn | Hacker News Reader

> The low density of Charlotte means a transport network like Munich’s is not viable, but the city could take its pre-existing light rail network and join it up to the extensive network of railroad lines around the city that are currently used only for moving freight.

This is not a feasible option due to the vast difference in crashworthiness standards between US freight rail and other system types such as light rail. The FRA actually prohibits allowing these two types on the same network of tracks at the same time. However, they could use a line along the right-of-way were it big enough to accommodate another set of tracks.

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This actually changed fairly recently in 2018 and European rolling stock, including tram trains are allowed under alternative compliance regulations.

Older American regulations favor pure buff strength. European regulations tend to emphasize making collisions impossible by using signalling and automatic emergency stop braking, and then crumple zones and other safety technologies. And the US has ended up adopting similar signalling regulations anyways with PTC, so now it is perfectly fine to allow European rolling stock. We already emphasize safety technologies over buff strength in US car regulations.

https://railroads.dot.gov/regulations/federal-register-docum...

Interesting - I wasn't aware this covered tram-trains. I was under the impression it only granted the exception to lighter off-the-shelf EU equipment like Stadler FLIRT or Siemens Desiro.

It's the same safety regime - the way tram-trains work (the only way they can work really) is by being compliant with the regulations that apply to regular trains.

In quite a few cases, old rail right-of-ways near cities are large enough for an extra track or few. Because, back in the heyday of American railroads, they either had another track or few, or they expected to.

The biggest issue is often bridges. Retaining the land that additional track(s) were on is fairly cheap. Building and maintaining rail bridges is not.

And building the light rail bridges for a transit system is not cheap. It's just less horribly expensive than building bridges which you could run strings of 220-ton freight locomotives over.

Funny reason there used to be double tracks almost everywhere that is now single tracked: while the government granted the property to the railroads, they still excised a tax over the portion of that land used by the railroads, so in the 70s when companies were going bankrupt left and right they tore up their own infrastructure to reduce the tax burden. Hell of a fuckup.

Not exactly...

To really be usable - by revenue-generating trains - track has to receive regular maintenance. Which costs money. If your RR is desperately short on both revenue-generating trains and money, then it's kinda obvious that you cut the no-longer-necessary expenses.

And railroad rails are steel, generally weighing 100+ pounds per yard. Scrap steel sold for far fewer dollars per ton in the '70's - but you get about 200 tons per mile of unused track that you tear up.

Hadn't considered the scrap value. Yea that might be a nice cash injection for a failing railroad.

Is there a reason you couldn't build new light rail trains to a higher level of crashworthiness than they are currently? I don't know the full details, but that's how tram-trains in Sheffield, UK were allowed access to the main railway network.

Unfortunately no. The main difference is mass - US trains are vastly heavier than anything in the UK so by the time you make a tram crashworthy it isn't a tram any longer.

That said, I believe the FRA did allow lighter designs such as the Siemens FLIRT for commuter lines so the rules are definitely less onerous.

After a couple train crashes the FRA mandated PTC signalling everywhere, and in a world in which trains come to an automatic stop unless explicitly authorized to operate in the next segment, the old buff strength rules are not as important.

Also, the old buff strength rules were not great at keeping people alive. 25 people died in the Chatsworth train collision that led to the PTC mandate, which compares poorly to a similar crash between two trains in Germany which killed 12. There is a reason why buff strength has not been the criteria for automobiles for decades.

https://en.wikipedia.org/wiki/2008_Chatsworth_train_collisio...

https://en.wikipedia.org/wiki/Bad_Aibling_rail_accident

It’s done in various places. NJ Riverline is an example. There are a bunch of others.

The bigger problem is the freights just have no interest in sharing the tracks with passenger trains, and requiring heavier and more expensive passenger trains is a convenient way to price the project to death.

How does this work for say, the New York and Atlantic Railway which runs freight trains on the same tracks as the Long Island Rail Road? There are stations where a freight train passes through while a passenger train is behind it.

The LIRR is heavy rail rather than light rail.

I don’t know the regulations but that’s probably why.

You're correct. LIRR trains are built to a much heavier standard and thus are allowed on the same tracks as freight rail.

Does the locomotive weigh half a million pounds and have no passengers? Then it’s heavy rail.

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