Urban areas are just a small minority of where the tracks need to go, as such if the train goes half the speed in the urban area we are still okay on overall trip time. In fact I suspect (read I don't know because it hasn't really been tried) that HSR should probably do a bunch of stops in the urban areas anyway so it won't get up to speed.
Re:Getting High-Speed Rail Wrong
by bobthepanda on Friday May 14, 2021 @11:42PM
(#27162132)
When I say "urban area" I mean the continuous built up urban area into the suburbs. American sprawl means that metropolitan areas are much further spread out than their European or Asian counterparts, to the point where most of Boston-Washington is sprawl and very little of it is farmlands.
In any case when you start building HSR it becomes progressively harder to eke out savings and the highest come from urban area speedups. Going from 50 to 100MPH cuts a lot more time than going from 150MPH to 200MPH. And the former simply doesn't work in the median of a highway.
The rail solution to that would probably be a tunnel. A tunnel is a cheaper affair with just two tracks than if it has to be wide enough for two tracks and six to eight highway lanes.