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> a very large percentage of the rail lines are built either on elevated tracks near populated areas, or underground for sections This is absolutely not true i

> a very large percentage of the rail lines are built either on elevated tracks near populated areas, or underground for sections This is absolutely not true in France, where the TGV mostly takes regular lines to exit the suburbs of every city it goes through. > It appears in the US many of these plans rely upon lower costs where the train is built on the ground. So they end up building tons of small bridges, regrading roads, moving wires, moving drainage, communication equipment etc as the train interacts with existing infrastructure Building elevated is a shit-ton more expensive

xt00 3y ago
Yea the costs for sure will vary a bunch -- but just searching around a bit I found this: https://pedestrianobservations.com/2012/09/25/relative-costs-of-transit-construction/ https://pedestrianobservations.com/2012/09/25/relative-costs... That cites some Danish study about elevated vs. non-elevated costing roughly 2-2.5X. Really my point to highlight is that building on the ground ends up in reality being far more complicated than piling up ballast and sleepers on the ground and mounting tracks to that and assuming you don't have many roads. Of course if you are crossing vast areas with virtually no roads or infrastructure, yes use the cheapest option, but in the areas where its just one complicated crossing after another, then you end up with tons of "mitigations" as they call it costing tons of money -- and when that is properly factored in, the cost difference is far less than expected. That's great that France has the TGV mostly on the ground as they exit the suburbs of every city -- whats the typical configuration of the crossings for roads? Does the road basically go in a small tunnel under the crossing or does the track become elevated temporarily? Or do they actually allow cars crossing the tracks at grade?

xt00 3y ago

Yea the costs for sure will vary a bunch -- but just searching around a bit I found this: https://pedestrianobservations.com/2012/09/25/relative-costs-of-transit-construction/ https://pedestrianobservations.com/2012/09/25/relative-costs... That cites some Danish study about elevated vs. non-elevated costing roughly 2-2.5X. Really my point to highlight is that building on the ground ends up in reality being far more complicated than piling up ballast and sleepers on the ground and mounting tracks to that and assuming you don't have many roads. Of course if you are crossing vast areas with virtually no roads or infrastructure, yes use the cheapest option, but in the areas where its just one complicated crossing after another, then you end up with tons of "mitigations" as they call it costing tons of money -- and when that is properly factored in, the cost difference is far less than expected. That's great that France has the TGV mostly on the ground as they exit the suburbs of every city -- whats the typical configuration of the crossings for roads? Does the road basically go in a small tunnel under the crossing or does the track become elevated temporarily? Or do they actually allow cars crossing the tracks at grade?