Interlocking Preview: ESA

Today, we'll take a look at one of the LIRR's two new interlockings slated to go into service once East Side Access is completed.  The two brand new interlockings that will help ferry trains to and from the LIRR's new station deep under Grand Central are to be called ESA and PLAZA.

ESA, short for East Side Access will be on the Manhattan side of things, deep underneath Park Avenue.  This interlocking will take trains from the two new tunnels currently being built, and align them to platform at one of the eight new tracks at Grand Central.  PLAZA will be the other interlocking, that one will be located in Queens, but we'll get more on PLAZA once we get that far in the Interlocking Walkthrough's.

ESA will basically consist of three parts: the crossover cavern, the upper/lower level split, then the split into the individual platforms.

Fashioning a diagram for ESA was quite challenging, as considering it doesn't exist yet and I'm a mere commuter and non-railroad employee, I'm not exactly sure as to what the layout would be.  But after combing over lots and lots and lots of project documents I'm fairly certain it will look something like this.  Now the crossovers might be flip-flopped or the upper level tracks might swing to the side instead of the lower level ones, but this is the gist of it.

I made the diagram much bigger, much more dramatized with the lines and crossovers and all.  If you click on the diagram with the center button of your mouse or right click the image and open it in a new tab, you can zoom in and view the layout closer up.

Here's the diagram for what ESA would look like.  I didn't put any milepost information in, but you could expect the bumper blocks at the station to be around MP -2.0 (hehe, negative mileposts!):

Part 1: Crossover Cavern
The first "part" of ESA interlocking you reach when coming towards the station from Queens is the Crossover Cavern.  The Crossover Cavern is the first place where the two tunnels, that have been virtually completely separate in their own little circular holes up to this point, meet up.

In this Crossover Cavern is a pair of crossovers (no kidding!) so that an inbound train can switch over to platform at the tracks in the east station cavern (303-304-403-404) and trains leaving platforms from the west station cavern (301-302-401-402) can switch back to the outbound track for the trip to Queens.  These guy's will be mightily busy as every single train set that comes into or out of GCT will have to change tracks on either their way in or way out.

Part 2: Upper Level/Lower Level Split
The actual station itself will consist of two giant station caverns, a west station cavern and an east station cavern.  Each of those caverns will have two levels, enough to fit four tracks and two platforms, one on top of each other.  So essentially there will be an "upper level" with two tracks in the east cavern and two in the west, and a "lower level" with two track in the east cavern and two in the west cavern, directly underneath the respective ones in the upper level.

To accommodate this, there will be a split in the two tracks just before the station.  A lower level track will swing off to the outside of each track, and the two remaining middle tracks will stay straight into the upper level.  The lower level track then goes off to the side and descends the small incline to get to the lower level.

The diagram above shows where these two lower level tracks swing off to the outside.  Then there is a red dashed line that shows where the lower level tracks are removed from the diagram out to the right so you can see them (the two red platforms will be directly underneath the two upper level platforms in real life, and imaging it that way would make them impossible to see).

Part 3: Station Tracks
Next each of the four tracks (the two lower level tracks that swung out to the sides above and the two upper level tracks that stayed straight) split into two tracks each, and platform to either side of one of the platforms in the station caverns.

So, for example, if I'm on an inbound train to GCT, I pass through the crossover caverns and don't change tracks, and I stay straight and don't go off to the side on the lower level track, my train then goes down a little bit more before there's another crossover that would split me to the either side of one of the platforms, to either track 301 or 302 in this case.

The station tracks will be numbered 301-304 and 401-404 (unless they go 200-203 and 300-303, or something like that, which I'm not sure), but for all intents and purposes now, let's just say 301-304 and 401-404 (I'm sure the signs for which tracks are which will be the last things the LIRR is thinking about now, so let's not nitpick the point, please). 

The 300-series tracks would be the upper level tracks, and the 400-series tracks would be the lower level tracks (keeping with Grand Central's existing numbering style).  Tracks 301-302 would be in the west cavern on the upper level, tracks 303-304 would be in the east cavern on the lower level, tracks 401-402 would be in the west cavern on the lower level, and tracks 403-404 would be in the east cavern on the lower level.  Just like this:

 

Now if these track numbers are going to be the ones seen on all the signs sometime down the road remains to be seen,  but for illustrative purposes, just go along with it for now.

So you can basically picture each pair of tracks in the next to the four platforms above will merge into one track.  Then the upper and lower track from the respective caverns will merge into one, then finally the east and west cavern tracks will exchange tracks at the crossover cavern before finally continuing out to Queens.

So that just about wraps up this ESA interlocking preview.  It's far too early to tell anything about speed limits, towers, or signals, but it's probably a good bet that the whole shooting match would be controled either from JCC (Jamaica Control Center int the AirTrain building) or PSCC (the folks who control everything in and around Penn Station, including HAROLD interlocking where the trains from GCT will eventually join the rest of the LIRR.  GCT won't have a western neighbor, because all the tracks will be stub-ended and will end in nice, pretty bumper blocks in front of a wall painted by some silly artist as part of the MTA Arts for Transit racket.  To the east, trains will next approach PLAZA, then HAROLD before making their way to their eastern destinations. 

If you have any questions or would like further clarification, don't hesitate to contact me.  I'll try to help as much as I can, but keep in mind I'm only a lowly passenger who's doing all this off the top of his head, so bear with me and don't get mad when any of it turns out to be false!