Airport Check-in on the way there
Transit idea #2. Air travel is getting to be like hell, with searches and the need to get there so far in advance of the flight to be sure you will get through security that it cancels much of the benefit, turning 40 minute flights into 3 hour ordeals. High Speed train advocates point out the downtown-to-downtime time of the train on routes of 300-500km beats or is competitive with the plane, and it's true.
But this would not be true if they could check you in and through security while on the train, bus or ferry to the airport, and then said bonded carrier took the cleared passengers directly to their gates in the cleared section.
Imagine you board the special airport train downtown. Security personel and airline agents move through the car on the trip with wireless terminals, metal detector wands and an X-ray machine. Their machine moves down the aisle (a bit easier in a ferry than a bus I will admit, but it could be designed) and everybody behind them is cleared, everybody ahead of them waiting, until they get to the end, and the whole train/bus/ferry is cleared. Then, if not on a bus, you are dropped where you can transfer to special busses which drive around the inside of the terminals on that little road, dropping you at stops near your gate in the cleared area. Your checked bags were stuffed at the back of your train and are put on the right conveyers.
This was easier to work out before 9/11 but I still think it could be done. And many passengers would happily pay a fair bit extra for this, because the result -- by making use of the otherwise dead time heading to the airport -- would be to have a zero-time trip through check-in and security.
You could even insist on web pre-checkin to smooth the process. Even people who lived closer to the airport than downtown might find it worth the time to get this train.
The handicapped would need a way to get from ground level to the jetway
entry level. Probably require airport staff to escort them to elevators in such airports. Or they would (if the ADA allows this) be forced to use the existing system. Does the ADA forbid improvements for those who can climb stairs and keeping the status quo for those who can't?
It would also reduce congestion at the airport and the existing security stations and free up parking and reduce private car exhaust. A win all round, worthy of the cost of any extra security staff or machines.
Those without checked luggage could schedule to arrive at the gate 15 minutes before take-off the way we used to be able to do on short flights, if using a ferry or train with dedicated right of way. With checked luggage you would need to go earlier to give them time to rape that.
This kills the argument in California that a high speed train from SF to LA would be worthwhile compared to the current downtown to downtown time. You would get the best downtown to downtown time by putting in such rail just from the downtowns (and other places) to the airport, and using the time on the train to advantage.
Update: I have expanded on the idea on this page on transit checkin