The Montauk Branch is the name given to the diesel trains that ran along the 80 eastern-most miles of unelectrified Montauk Branch that extends 115.8 total miles from Long Island City to Montauk. Service on the branch has two distinct personalities with relatively frequent generally hourly (but not quite clockface with a few two hour gaps in service) service from Patchogue and points west, additional service particularly during early mornings and evenings to and from Speonk, the location of the only yard in the middle of the branch. Service is very limited, with just 6 trains per day with increases on Summer weekends, run the remaining distance through the Hamptons to Montauk. The line is double tracked for it’s first 13 miles from Babylon to just after the Sayville Station and single-tracked with passing sidings the remaining 67 miles to Montauk.

How this branch receives service and where passengers need to connect to electric trains to reach Penn station also varies. There is roughly Hourly ‘Scoot’ service between Babylon and Patchogue, generally connecting to Babylon Branch electric trains (some are the regular half-hourly locals, some special expresses) to Penn Station. Some of these trains (particularly in the mornings and evenings) originate or terminate in Speonk where the only train yard between Babylon and Montauk is located, and some trains are through trains all the way to Jamaica. During peak direction rush hours, 2 AM trains (one originates in Southampton)and 1 PM train use dual-mode equipment and provide a one-seat ride between Speonk and Penn Station. On Summer Fridays there is an increase of 3 trains eastbound primarily designed to provide extra capacity for New Yorkers connecting to ferries to Fire Island. Two of these trains are added between Patchogue and Babylon, with the 5 days a week Montauk-bound train at a similar time now making fewer stops, with the skipped stops now served by the additional train. A third from Jamaica to Speonk, stopping at Babylon 1:21pm, fills a two-hour gap in service between 12:21pm and 2:21pm on the normal weekday schedule.

Service is much less frequent west of Speonk, for all of the branches Zone 16 stations (LIRR’s fare zone farthest from Penn Station). Off-season service between West Hampton and Montauk has just 6 trains per day, all service – except for one round-trip on weekdays that requires changing to/from an electric train at Babylon – provide through service to Jamaica, with one weekday rush hour trip extend to Hunters Point Avenue (and Long Island City in the AM rush hour only). Some of these trains skip stops between Babylon and Patchogue to provide faster trip times. The trains are not well spaced out throughout the day, on weekdays year-round it is impossible (unless you don’t mind getting back to New York City after 1:00am), to take a full day trip out to the Hamptons because there is a gap in service leaving Montauk between 2:48pm and 10:05pm. Conversely on weekends Hamptons residents who want to visit New York City must contend with a 9 hour gap in service leaving Jamaica between 12:10pm and 9:36pm, with the weekend schedule better designed year round to accommodate weekend visitors to the Hamptons from New York City.

The Long Island Railroad does provide extra seasonal service on the branch for people escaping New York City for summer weekend getaways (although none operated during Summer 2020 due to stay at home orders from the COVID-19 pandemic). On Fridays there are 4 additional afternoon trains that run to Montauk, with 4 trains (although one originates in Southampton) returning to Jamaica on Sunday afternoons. One of these trains is named the Cannonball, a name that has existed for this express service for over 100 years. The Cannonball leaves Penn Station (before 2013 it left from Hunterspoint Avenue and historically from Long Island City) and runs non-stop to Westhampton. The train used to run Eastbound only, but in 2013 a Westbound counterpart was added with a one-seat Sunday afternoon ride from Montauk into Penn Station (this train stops in Jamaica for connections). This train before the COVID-19 pandemic (through the 2019 season) included the up-charged Hampton’s Reserve Service which included reserved seats in C3 cars specially equipped with cup holders and train attendants providing at seat beverage and cocktail service. The Hamptons Reversed service was introduced in 2001 to replace the former all reserved Parlor cars that were provided with special train cars (with 2 by 1 seating and built-in bar areas) on the now all retired single-level push-pull diesel fleet. A train also leaves Penn Station at the same scheduled time as the Cannonball on Thursdays (it has never had reserved seats or other amenities) and for the 2021 season runs 10 minutes faster than the Cannonball because the Friday evening Cannonball has extra dwell time built into its schedule at intermediate stops for its heavy loads, short platforms at the stations in the Hampton’s require passengers to sometimes walk forward or back to reach a platforming door. On Monday mornings there is finally one additional westbound train from Montauk to Hunters Point Avenue.

Diesel Montauk Branch trains that run through to Jamaica from Babylon can take one of two routes via the Babylon Branch (the name given to trains on the electrified portion of the Montauk branch) or the Main Line. Trains that operate via the Babylon Branch all run non-stop between Jamaica and Babylon. Trains that run via the Main Line turn north just after Babylon, using the single tracked 6 mile long Central Branch to run north to the Main Line, joining what’s advertised as the Ronkonkoma Branch between Babylon and Bethpage. One Hunters Point Avenue-bound AM rush train stops at Mineola and Hicksville, plus two return trains, one is the middle of the night Montauk bound train that stops just after 1:00am at both stops, plus an additional Patchogue-bound train that stops at Mineola only at 3:19pm.

Originally diesel trains running between Long Island City and Montauk on this branch could run nearly completely separately from the Main Line (except for 2 miles around Jamaica) via the Lower Montauk Branch that ran on a line with grade-crossings with it’s own tiny low-level platform ‘flag stop’ stations at Penn Bridge, Haberman, Fresh Pond, Glendale and Richmond Hill (that actually had a high-level platform still visible from the J train subway near 121 Street). These intermediate stations closed in 1998, since it didn’t make sense to rebuild any of them into high-level platforms for the new C3 cars, and all passenger service on the Lower Montauk Branch (then provided by one AM train on the Oyster Bay Branch to Long Island City) ended just before Superstorm Sandy (it was scheduled in end in November) in 2012, since the costs and requirements of installing Passive Train Control (PTC) outweighed the benefits of keeping this station-less route in service. Freight service, provided by the New York and Atlantic Railway continues on the line to the present day. The need to provide high-level platforms at all stations also resulted in the closure of 3 additional Montauk Branch stations in 1998: Center Moriches, Quogue, and Southampton College.