This has to be a joke.
To load a train moving at 200 mph you would need 3 miles of platform track for every 1 minute of passengers moving between the platform and train. Do you honestly see 300 people including elderly couples and families with strollers and toddlers moving between the platform and the train in under 1 minute? You would need miles of platform track to do this safely.
And guess what guys? There are virtually no express rails left in the US. So retasking those for this idea is not happening. Why do you think the trains running today between Boston, NY, Chicago and a dozen other cities run hours slower than trains with steam engines did during WW II. Our brilliant government ripped up thousands of miles of track and sold it for scrap metal in the 1970s while they were busy expanding the highway system.
Because of those facts you just added hundreds of millions, possibly billions, to the setup cost of the HSR system to build hundreds of miles of additional high-speed rails and the power grid for them and to build the platform trains. Your per passenger operating costs just went through the roof.
For what? Gaining a few hours on a transcontinental trip?
This kind of ill conceived, poorly thought out idea is why HSR in the US is a joke.
