July 2014 Union Strike

A tentative deal between the MTA and LIRR Unions to avert a July Strike has been reached. See this post for more information.

Wednesday, August 7

Interlocking Walkthrough: MS (JJD)

MS Interlocking on the Montauk Branch consists of a pair of switches that make up a passing siding just east of Mastic Shirley.  MS, which stands for Mastic-Shirley, is located in Shirley, NY 62.5 miles from Long Island City by rail.  Here's a birds eye view of the location.

When doing some research for this post I found out that MS interlocking is not actually called MS anymore.  On May 18, 2009 the interlocking was renamed to JJD interlocking in honor of former LIRR president James J. Dermody.  Since it is more widely known as MS interlocking (and the name MS itself is much more descriptive than JJD), I will continue to refer to it as MS for the sake of clarity.

This interlocking is fairly simple in nature.  Much like DUKE interlocking on the Port Jefferson Branch, there is a switch just east of the station that allows trains to go onto the passing siding, which is located to the north of the tracks.  There is another switch at the end of the siding that allows trains to return to the main Montauk Branch track to continue east twoards either Speonk or Montauk.

MS (JJD) is split into two separate interlockings, like many other passing sidings on the railroad.  MS 1 (JJD 1) lies at the west end of the siding and MS 2 (JJD 2) controls the switch on the east end.

A train waiting on the passing siding at MS (JJD) interlocking.
The new color light signals are visible in the photo.
(Photo credit: YouTube user jkrspecnet)
The signals at MS (JJD) interlocking were recently replaced.  A couple years ago the LIRR upgraded the signals at PD, MS (JJD), and SK interlockings to the new color light signals that they've been installing.  These signals are similar to the ones that were put in at AMITYVILLE and WANTAGH interlockings a couple years ago.

The passing track at MS (JDD) is a couple feet lower than the mainline track for some reason, but it doesn't seem to hinder train operations in any sense!

MS (JJD) interlocking as we know it today was first put into service in February 1980 as MS interlocking.  For the first couple decades of its existence it was controlled from PD tower east of Patchouge.  However,  on May 6, 2006 the LIRR closed and razed PD tower and control over MS interlocking was remoted to BABYLON tower, where it is currently controlled from today.  On May 18, 2009 the interlocking was renamed to JJD.

The passing siding at MS (JJD) interlocking is actually used quite a bit every weekday.  Normally trains 2701 and 2702 meet around 2:30am, trains 2706 and 2707 will meet here around 12:50pm., and trains 2736 and 2743 meet around 2:12pm weekdays.  On summer Fridays trains 2708 and 2709 will run into each other here around 3:49 as well. 

MS (JJD) has three scheduled meets on Weekends: trains 8701 and 8702 meet here around 8:30am, trains 8719 and 8738 meet at the siding around 9:00pm, and trains 8740 and 8745 pass at the sidings around 12:15 in the morning.  On summer Sundays there is an additional meet that is held here, train 8707 (the lone Bridgehampton start) passes by train 8736 around 4:00pm here.

Below is a video from YouTube user jkrspecnet (with excellent commentary, I might add) of 2706 and 2707's meet at MS (JJD) interlocking.

East of here there are two noninterlocked sidings at MO (Center Moriches) and PT (Eastport) but they are not currently used at all in LIRR service.  The next interlocking is SK interlocking, the very last one on the Montauk Branch.  West of here there is a passing siding at Bellport, but the next interlocking is not until PD near Patchouge.


  1. Last sentence seems to have a typo: Bellport is not east of Speonk/Mastic Shirley (it is west of Speonk/Mastic Shirley)

    1. I should correct my last comment about the siding in Bellport being "unused". it possibly is also used on occasion by LIRR work trains, as there is a small LIRR equipment storage yard located on the south side of the tracks to the immediate west of the Bellport Station platform.

  2. Just found your excellent web site today. Thanks for including my video (and still photo from same) of the midday trains at Mastic-Shirley. Strictly an amateur at this, but I enjoy making videos of LIRR trains primarily for my grandchildren to watch, but post them on YouTube for public viewing and (hopefully) enjoyment. Please feel free to use any of my LIRR YouTube videos as you see fit.

  3. One more comment about the MS interlocking usage. Actually there is one scheduled meet on weekends that I am familiar with. I frequently ride Train 8738 from Jamaica to Speonk Saturday or Sunday evenings. Train 8738 meets Montauk to Jamaica Train 8719 at Mastic-Shirley. Usually, Train 8719 is on the passing track as we leave Mastic-Shirley station for Speonk and pass by it. Two weeks ago, however, Train 8719 was running late and we had to wait on the passing track for about 10-15 minutes until Train 8719 went by us.

  4. One further note about noninterlocked siding MO in Center Moriches. This is often used by LIRR work trains to unload ties, ballast, etc. Here's a YouTube video I made on August 16, 2013 of a work train with MP15AC Work Engine #171 and 7 gondola cars unloading ties: http://www.youtube.com/watch?v=LYICI1zqe0M

    Also, there is a similar unused siding at Bellport Station.

    1. Here's the corrected link to the work train video at the noninterlocked siding MO in Center Moriches on August 16, 2013:
      LIRR Work Train in Center Moriches

  5. Here's a video of Trains 2736 and 2743 at the MS interlocking yesterday afternoon October 11. This was the final run in 2013 of Train 2736. (hope this link works)

    1. Excellent video! The HTML coding for the comments can be tricky, but here's a working link to that video.

      ~ Patrick @ The LIRR Today

    2. Thanks for making the link work. Note the switch being thrown at 4:03.


Stay updated with The LIRR Today on Social Media!