Atlantic Terminal at the end of an underground passageway from the Barclays Center? Not for suburban train passengers

From the ever-arena-boosting Net Income, in Nets Daily, Could Atlantic Terminal Lure Isles?:

We haven't seen NHL commissioner Gary Bettman wandering around Atlantic and Flatbush in a construction helmet, carrying a measuring tape. Things have calmed down a bit regarding an Islander move to Brooklyn.

Still, there are some out there, like the Brooklyn hockey fans the Daily News found Tuesday, who want to see the Isles move 22 miles to the west despite a smaller capacity and questionable sightlines.

In the calculus, however, one thing isn't getting a lot of attention: the Long Island Railroad's new Atlantic Terminal, at the other end of an underground passageway from Barclays Center. Opened in 2010, it accommodates 25,000 LIRR passengers daily, many of whom switch in Brooklyn for subway rides to the Financial District. Some are suggesting that a return trip in the evening, with time out for a hockey game, could be a big lure for the Islanders and their fans.

One reason why it hasn't gotten a lot of attention is that the "underground passageway" is only for subway riders, not suburban train passengers.

That means those Long Islanders coming from work in New York City could get to the arena from the subway. However, they couldn't get to the LIRR from the arena. Nor could Long Island fans coming from home get to the arena from the LIRR.

From the Final EIS

Brooklyn Borough President Marty Markowitz in 2006 commented on the Atlantic Yards Final Environmental Impact Statement (FEIS):

The FEIS should examine the creation of a thru-ticketing arrangement for LIRR riders which enables them to pass through the paid zone for the subway to reach the Urban Room without payment of a subway fare. Otherwise, project generated trips via the LIRR would be required to use the existing entrance to LIRR’s street level concourse on Flatbush Avenue.

The Empire State Development Corporation responded:

MTA NYC Transit has indicated that a through-ticketing arrangement for game days is not feasible with current MetroCard technology. In addition, it would not be practical to physically separate LIRR passengers walking through the paid area from subway passengers due to space and circulation constraints within the station. For the purposes of the traffic and pedestrian analyses in the DEIS, it is assumed that all of the LIRR demand would occur on sidewalks and crosswalks connecting the project site with street-level entrances to the LIRR’s Atlantic Terminal.

That would mean a walk outside. It's about one-fifth of a mile--certainly doable, but not the same as an underground walk.