Edit: if you’re referring to Brightline West, construction hasn’t even started.
I just rode it last week, and it actually took 3 hours, not 3.5.
Most of the NEC corridor from DC to NYC has a speed limit of 125mph; from NYC to New Haven, it's generally 70mph (!), from New Haven thence to about Kingston generally 90mph, and from there to Boston it's mostly 150mph. Given the density of the corridor, Amtrak should be trying for 150-220mph speed limits, but even 125mph is generally agreed upon to be the lowest end of HSR.
A surprisingly easy way to make the train go faster would be to redesign the switching sections before large stations to allow trains to go faster through them. You can probably cut around 10 minutes out of the entire length with an investment of less than $100 million just by doing that.
In the UK and Europe, 125mph (~200 km/h) is considered the top speed limit of conventional rail. Legally, operating speeds beyond that require full in-cab signalling, positive train control, upgraded safety and structural requirements, and whatever else is required for HSR. Further, all the trains operating on a section of line need to be upgraded to those standards if any of them are to run at speeds > 125mph.
The UK does have some sections of conventional line that are capable of > 125 mph running, and even have done so in the past, but this is no longer allowed.
I’m not sure if the US has similar rules, but it wouldn’t surprise me if so!
> ”A surprisingly easy way to make the train go faster would be to redesign the switching sections…”
Yes, generally speaking, fixing the low-speed bottlenecks will typically yield the biggest benefits for the cost in terms of overall journey time.
So maybe it'd be a few billion at least. Not to say they shouldn't try. But I expect it'll be over budget and behind schedule, it would never happen like Brightline where they broke ground ASAP and just kept building until it was done.
(This doesn’t make the situation any less embarrassing.)
