Wednesday, September 18

Interlocking Walkthrough: POST

POST interlocking, a small and simple interlocking in Smithtown, is the subject of this week's interlocking walkthrough.   Split into two parts, POST 1 and POST 2 and located on either side of Smithtown station, POST interlocking and Smithtown station is used fairly regularly for meets on the Port Jefferson Branch.  There's almost always a meet here, from rush hours to weekday off-peaks, to all day weekends, POST interlocking fulfills a vital role in the single-track operation of the Port Jefferson Branch.



Like other Port Jefferson Branch interlockings, the two different parts of POST used to be known by different names.  From December 1963 until October 1977, the interlocking to the west of the station platforms was designated HARE interlocking, named after retired LIRR conductor James Hare.

When doing some research for this post, I noticed that there were two sets of "in service" dates listed for HARE interlocking.  The interlocking was in service from December 20, 1963 to August 26, 1981, then it was in service again from September 14, 1971 until it was renamed POST 1 on October 3, 1977.  For some strange reason or another there was a 20-day period in the late summer of 1971 where the interlocking was not in service.  I haven't a clue why the interlocking would have been taken out of service just to be put back in a couple weeks later, but I'll see if I can track down some answers and report back.

Nonetheless, on October 3, 1977, HARE interlocking fell victim to simplification, and the two minor interlockings to either side of the station were renamed POST 1 and POST 2.

POST interlocking, which originally went into service on December 20, 1963 along with HARE, was originally to the east of the station.  POST interlocking is named after retired signal department circuit engineer Howell B. Post.

The pair of interlockings themselves are simple in form.  On the west side of the station POST 1 contains a switch that allows trains from Kings Park and points west to come off a single track and go onto either of the station tracks.  POST 2 does the exact opposite and takes trains from the two station tracks and shoves them down into one track for the trip further east.

POST 1 is atypically set on a curve into the station.  The curve, which has a 40 m.p.h. speed restriction contrasts the more frequently seen 'one track swings into the other' layout of POST 2.  Otherwise, the speed limit is 65 m.p.h. for most of the Port Jefferson Branch between Huntington and Stony Brook.

From the very beginning of POST and HARE's existence on the LIRR their switches were remoted to DIVIDE tower in Hicksville where the movements through the interlocking are controlled there.

The signals at POST interlocking are still the older-style position light signals that are slowly fading away on the railroad.  To the west of the station in POST 1, the signals are on gantries.  To the east of the station I think they are dwarf signals (due to the proximity of the crossing), but I cannot be sure, it's been quite a while since I've been up this way on the LIRR.  You can see the signals that control POST 1 interlocking in the photo above.

That just about wraps up this week's interlocking walkthrough.  Join us again next week when we unravel the crazy and hectic QUEENS interlocking!

4 comments:

  1. Until the service mode of Huntington electrification and Port Jeff Scoots were fully implemented in May of 1972, Smithtown was the turn-back point of half the Port Jeff Branch weekday off-peak service: roughly 90 minutes up to there, then 3 hour intervals beyond, which was manual block railroad by the Port Jeff ticket agent also being block operator (which was the case through the 1980's).

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    1. Very interesting! Thanks for your continued insight, Mr. Versaggi!

      ~ Patrick @ The LIRR Today

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  2. Great article, but are you sure you have the correct photo? That looks like STONY 1 (at the west end of Stony Brook station) rather than POST 1. If it were POST 1 you would be able to see the Route 25 undergrade crossing just west of the platforms (which is also missing from your map), and the switch itself would be out of view around the curve.

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    1. Going back and looking at some satellite images of the two areas I think you're right. I haven't been out on that part of the Port Jefferson Branch in quite some time so when I found that picture on Wikimedia Commons with the caption 'POST Interlocking' I just went with it. Thanks very much for the correction, I've removed the original picture.

      Also, the Route 25 underpass wouldn't show up on the diagram. Those diagrams only show grade level crossings, not anything that goes above or underneath the tracks.

      ~ Patrick @ The LIRR Today

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