U.S. Sen. Charles Schumer was at Stewart Airport this morning to announce more funding for a study on how to link the Orange County airport to Metro-North Railroad’s Port Jervis line. The study will begin June 2, rather than in a year or so. Creating a rail link at Stewart would mean Manhattanites could jump on a train and get to Stewart once the Access to the Region’s Core project gets done. (the ARC tunnel will allow those “west-of-Hudson” rail lines to go directly to Manhattan’s West Side, so there’s no more changing trains in Secaucus.) Schumer’s been a big proponent for the ARC project, and a rail link to Stewart would certainly up ARC’s value.

So, here’s the question: Does this enhance or diminish the a commuter rail option for the Tappan Zee Bridge/Interstate 287 Project? The TZB/I-287 Project Team is due to announce this month what kind of public transportation option is planned for the 30-mile I-287 corridor between Suffern and Port Chester. That will also determine if the Tappan Zee Bridge would be rebuilt, expanded or replaced.

ARC has already caused the TZB/I-287 Project Team to take another look at forecasts for ridership of any public transportation system (options include commuter rail, bus rapid transit and some mixes along the corridor). Would a direct ride to Stewart on the Port Jervis line mean that there would be more or less demand for an east-west rail line across the Lower Hudson Valley?

Here’s one thought:  The TZ corridor project would already link whatever public transport method to the Port Jervis line. So, if that’s going to provide a one-seat ride to Stewart from Tarrytown, White Plains and Port Chester, that’s a real plus for the commuter rail option. Sure, a rapid bus to the train will get riders there, too, but that “one-seat ride” mantra is a powerful one.

Maybe what ARC takes away this rail link to Stewart will bring back. Nah, it couldn’t be that easy.