Comment by iso1631

Or perhaps take that large railway car, put a few together, and run then on or through the ground direct from the airport to a few downtown locations every couple of minutes. The efficiency per person would be ridiculously high (20,000 an hour), and I suspect the individual end-to-end speed would be faster than by air

15 minutes for JFK to West 34th Street is just 14 miles. That doesn't include any boarding/off boarding process, which are far faster in a train than anything, including in a taxi.

That's about the distance from Heathrow to Paddington which also takes 15 minutes.