The development agency is soliciting expressions of interest in the project from private firms who would be expected to foot the entire bill, reaping an eventual profit from fares. Previous studies of one-seat ride options suggest that - depending on ticket price - roughly 11,000 riders would make the trip to and from Manhattan daily. 2,600 of the trips would be by airport workers.

Simultaneously, the MTA is polishing off a Manhattan-airport one-seat ride proposal, while the Port Authority is moving ahead with its own Air-train line to run between Jamaica Station and JFK. With all these projects in the mix, political and engineering challenges await any ESDC-forged partnership. The one-seat route would use LIRR main-line tracks from Penn to Jamaica station, then switch to Air-train tracks at Jamaica for the trip to and around the airport.

The ESDC envisions trains traveling from Penn Station every 12 to 15 minutes. A Port Authority spokesperson said current thinking there has the Air-train running with a 4-5 minute head-way and that "one-seat ride" trains from JFK, when and if they come on line, would be fit into circulation by taking up 4 of the 12 slots available per hour. Peak-hour line-sharing may be more difficult to negotiate on the LIRR main-line, especially with planned service expansion to Grand Central.

Air-train stations are to be built with on-platform doors, and the route involves turns too tight and grades too steep for typical heavy-rail cars. For all these reasons, a new, yet-to-be designed hybrid car would be needed for the one-seat system.

Given all these difficulties, ESDC's advertised time-line for a one-seat ride to JFK by 2004 seems wildly ambitious, leading some to wonder whether last week's announcement carries any weight. Jeffrey Zupan of the Regional Planning Association speculated that the ESDC could be simply "stirring the pot" in order to spur action by the Port Authority and MTA.

In the meantime, NJ Transit should be able to offer a ride from NY Penn Station to the Newark Airport monorail by early next year. Newark has become increasingly popular among NYC air travelers: since 1990, while JFK departures have increased by less than 4%, Newark trips have ballooned almost 30%.