The Great Neck Pocket Track is an important piece of rail infrastructure (argued to be the most important infrastructure piece). The pocket track is what gives the Port Washington Branch a good boost during rush hours.
The Port Washington Branch, like most branches of the LIRR, is double-tracked for a lot of its length, however, that double tracking is reduced to a single-track line at NECK interlocking, just east of Great Neck. This single tracked line is probably the worst bottleneck in the entire system. By substantially limiting the amount of trains that can get to Port Washington and turn back west and vice versa, the single track segment could paralyze the entire line if not for the pocket track.
The main problem here is Port Washington Yard. Basically, the LIRR doesn’t have enough room in Port Washington to store the amount of trains needed, and NIMBY’s won’t let them add any more. So basically, once the yard fills up, the LIRR has no choice but to run trains back west, but how do you do that if the line is single-tracked? Well, they have to stop eastbound service to allow enough time to let some of the pressure off the yard. If the LIRR could boost capacity to include even just an additional 2 yard tracks in Port Washington yard, it would help a lot, but they can’t, so, we’re stuck with what we have.
The pocket tracks allows the LIRR to split the line into two segments: Main St to Great Neck and Great Neck (or Bayside) to Port Washington. By running some trains express along the portion between Flushing and Bayside/Great Neck during rush hours as “outer zone” trains and having some trains terminate at Great Neck as “inner zone trains” not only does it fulfill capacity, but it also distributes the loads, and allows for smart terminal management. The thing is, without the Great Neck Pocket Track, the LIRR would have to cut 16 trains from the schedule and make all the trains local!
As you can imagine, that wouldn’t end well. But then, The Great Neck Pocket track steps in to save the day. The pocket tracks allows the LIRR to get trains out of the way and turn them back west in order to not clog up Port Washington yard. So, the pocket track is in a great location, it allows for trains to turn without being in the way of thru-trains to Port Washington, and it allows the busier stations west-of Great Neck to get the full advantage of double tracking.
I’ll be talking much more about the Port Washington Branch soon, so stay tuned!