Reverse tracking on metro north ?

[Juelz4309]

I had the pleasure of takin the metro north into work this morning (friday) from williams Bridge in the bronx becuse the 5 was suspended and i just didnt want to sit on the 2 local...so i walked down to the station and waited ...while i waited i noticed 2 trains comin down what would be the express uptown track!!! I dont ride metro north often so i dont know if this is common thing...so there were pretty much 3 tracks for manhattan bound service and 1 for northbound service...Considering there are no signals in visual sight it kinda freaked me out!!!..can someone explain how this works and why? thanks...

[lirr42]

Trains can run on any track in any direction, especially in the Bronx lately with the Bronx Right-of-Way Improvment project taking various segments of track OOS and making the rush hours all loopy, so what you've seen is perfectly normal.

 

Also, Metro-North does not use wayside signals in the way NYCT does.  MN trains run on a cab signal system where the signal indication is displayed in the cab of the train.  They have simple "go/no-go" signals at interlockings, but everything else is off the cab signals.

[QM1to6Ave]

Can you explain what cab signaling is in more detail? People keep mentioning it. Does it mean that cabs communicate directly with other cabs, much like a CBTC type system?

[Jsunflyguy]

Cab signalling is roughly analogous to the automatic wayside signals you can see on NYCTA or class 1 freight railroads out west. The locomotive/cab equipment detects codes relayed through the track that give certain indications. This technology came about in the 30's, it's still a fixed block, nothing revolutionary going on here. In reality it's just sending the indications that would be displayed on wayside signals straight into the locomotive.

CBTC is where two trains are aware of each others position as well as other features of the line and use that to constantly determine the safest speed creating a moving block (except in interlocking areas which are fixed blocks regardless) which can increase line capacity.

[bobtehpanda]

Can you explain what cab signaling is in more detail? People keep mentioning it. Does it mean that cabs communicate directly with other cabs, much like a CBTC type system?

 

CBTC usually involves cab signalling if a driver is involved, but cab signalling does not include CBTC.

 

The way I understand it, at a very basic level signals are not hoisted on wayside gantries or poles or what have you, but in the cab itself (recieved somehow through wayside equipment). This is because above a certain speed (which I believe the FRA has set at 79 MPH), seeing a signal clearly becomes very impractical. It also provides a continuous reminder to the driver as to what the last signal displayed.

[nostalgia]

Can you explain what cab signaling is in more detail? People keep mentioning it. Does it mean that cabs communicate directly with other cabs, much like a CBTC type system?

I preface my remarks that the information I'm writing may be out-of-date. The wayside signals have two aspects: red or flashing green. Red means stop and flashing green means proceed per cab signal indication. The cab has a number of lights. One of them will illuminate based on the traffic conditions. The lights have speeds. The first may be 0-15, second 15-30, third 30-45, and I don't know the rest. These cab signals replace the wayside signals of Approach (approach next signal not exceeding 30 mph prepared to stop at next signal), approach medium (approach next signal not exceeding 30 mph), etc.

 

Amtrak cab signals are clear, approach limited, approach medium, approach, and restricted. Operating rules define the maximum speed for each cab signal.

[lirr42]

Just to chime in quickly and build upon what others have said and I'll post more detailed stuff later in the week when I have more time.

 

Like what Mr. Nostalgia said, there are simple go-no go interlockings at interlockings and otherwise signal indications are transmitted into the train's cab.  In the cab, there are four indications that one could receive:

 

N  (Normal, MAS)

L  (Limited, usually 45mph or 60pmh)

M (Medium, usually 30mph)

R  (Restricting, usually 15mph)

 

M8's also have a second column of aspects that displays

80

60

30

S

[QM1to6Ave]

thank you guys for the explanation! Here I thought cab signalling was some brand new technology...apparently not lol, though it is a pretty smart idea. 

[lirr42]

The LIRR also uses cab signalling to some extent.  While they still have wayside signals along the way, cab signals/speed indicators in the cab also play a role in the process.

[Truckie]

For the most part the information given has been correct with some minor additions.

 

First and formost, on Metro North East of Hudson territory all wayside signals, correct term being interlocking signals, are placed at all interlockings and are basic go/no go signals with few exceptions.

 

The interlocking signals the ability to give three indictions:

 

1) Proceed Cab (flashing green) meaning proceed at cab signal indication. 

2) Stop (two steady red aspects) meaning stop.

3) Absolute Block Signal (alternating single green and two red) meaning proceed to the interlocking signal at restricted speed, slow speed with in the interlocking and MAS not exceeding 59 MPH outside of interlocking limits aproacing the next interlocking signal prepared to stop (more on this later).

 

Now on to the cab signal system.  There are currently 4 cab signal aspects:

 

Normal Cab: Proceed at MAS (maximum authorized speed).

 

Limited Cab: Proceed at Limited Speed (45 MPH passenger/25 freight)

 

Medium Cab: proceed at Medium Speed (30 MPH Passenger/15 freight)

 

Restricted Cab: Proceed at Restricted Speed (a speed that will permit stopping within 1/2 the range of vision, looking out for train, obstruction derail or switch improperly lined, looking out for broken rail, and not exceeding 15 MPH for the entire movement).

 

There are other aspects that are already installed (but not in use) on the M8's and slowly being installed on other equiptment that will be used for PTC.

 

The cab signal system is what is used to give an idea of the status of the next block.  There are electrical pulses sent through the rail that will tell the train what's ahead.  Example if the next block is occupied, then the cab signal should indicate a restricted cab.  If the next block is clear but 2 blocks ahead is occupied then the cab signal should be a medium cab, and so on.

 

Should there be any malfuntion of the cab signal system, then that's where an absolute block interlocking signal comes into play.

 

There is one location on the property that has standard Norac wayside signals (Clear, limited clear, etc).  That's at CP75 for (north of Poughkeespsie station) north direction travel.  This is where division post Amtrak is located.

[paulrivera]

Trains can run on any track in any direction, especially in the Bronx lately with the Bronx Right-of-Way Improvment project taking various segments of track OOS and making the rush hours all loopy, so what you've seen is perfectly normal.

 

Also, Metro-North does not use wayside signals in the way NYCT does.  MN trains run on a cab signal system where the signal indication is displayed in the cab of the train.  They have simple "go/no-go" signals at interlockings, but everything else is off the cab signals.

 I was just on an NH line train and my train went "reverse tracking" from Greens Farms all the way to Stamford, which also kinda caused the Stamford local to GCT to arrive on track 4 instead of 3 or 5. The announcer at Stamford said over the PA even said that it was a "once in a lifetime" event and that even he wishes he was on track 4 .