Jump to content

Attention: In order to reply to messages, create topics, have access to other features of the community you must sign up for an account.
Nick

headway shortened to 90 seconds? or not and are trains somewhat tailgating?

Recommended Posts

3 hours ago, Deucey said:

So even if (MTA) can achieve 30 TPH on certain lines, where are they gonna get the extra trains necessary, since the orders for new cars now are basically replacement for existing livery?

By ordering them? It ain't rocket science, and at the rate they're installing CBTC we'll be ordering the next set of cars by that time anyways.

I don't know where the RPA says 30TPH is the best you can do with CBTC, because we already run 30TPH today, on the Queens Boulevard Express. But we all know the RPA is off their rocker.

Share this post


Link to post
Share on other sites

18 hours ago, bobtehpanda said:

I don't know where the RPA says 30TPH is the best you can do with CBTC, because we already run 30TPH today, on the Queens Boulevard Express. But we all know the RPA is off their rocker.

If 30 is the best we can get with CBTC, then it's a spectacular waste of money (it's not, though). 30 tph is the existing limit with block signalling; CBTC can get that up to 36-40, terminal capacity permitting.

Share this post


Link to post
Share on other sites
On 4/23/2018 at 8:37 PM, Nick said:

The headway is typically 2 minutes 24 seconds to 3 minutes as of last September, at least where the system uses fixed-block signaling (almost the entire system still using it), although I don't know if that typicality was a minimum or an average. "CBTC can run 40 trains per hour per line, or a train every 90 seconds. Due to physical limitations in the system, the best the subway can hope to see with a CBTC system is probably around a train every 120 seconds, or 30 trains per hour; still, that’s an improvement over today’s subway, which typically runs only 20 to 25 trains per hour." This is according to Rich Barone, of the Regional Plan Association, according to The Village Voice, September 7, 2017 (https://www.villagevoice.com/2017/09/07/meet-the-century-old-technology-that-is-causing-your-subway-delays/ (as accessed 4-22-18)).

The L line has CBTC and the #7 line is being fitted with it, according to the same Voice source, so I don't know if the #7 has shorter headways yet. I just took the L twice in the pm rush hour and the actual headways were sometimes about a minute.

In answer to my opening post, we mostly do not have 90-second headways, if we have any besides on the L, but trains may be switching tracks so that same-minute arrivals are not likely dangerous.

The entire system was designed for a maximum capacity of 40tph, or maximum service level of about 34-36 tph. Years of signal mods and timer installations have reduced that to as low as 20 maximum in some areas. Some lines where capacity is critical (Queens Boulevard being a good example) have been modded in a way that preserves service levels, but others (Concourse, 4th Avenue, Fulton being good examples) have seen their capacity severely affected by all these changes. And to be clear, these changes aren't junctions. This is normal, straight track having capacity slaughtered. 

  • Upvote 2

Share this post


Link to post
Share on other sites
1 hour ago, RR503 said:

The entire system was designed for a maximum capacity of 40tph, or maximum service level of about 34-36 tph. Years of signal mods and timer installations have reduced that to as low as 20 maximum in some areas. Some lines where capacity is critical (Queens Boulevard being a good example) have been modded in a way that preserves service levels, but others (Concourse, 4th Avenue, Fulton being good examples) have seen their capacity severely affected by all these changes. And to be clear, these changes aren't junctions. This is normal, straight track having capacity slaughtered. 

125th to 59th southbound on the (A) today took me 12 minutes. I'm guessing there was a (D) up ahead, but even still, that's absurd, and with trains going that slow, you're never going to get the maximum potential capacity out of any track.

  • Upvote 3

Share this post


Link to post
Share on other sites
On 4/13/2018 at 2:49 AM, bobtehpanda said:

As far as power supply goes, you also have to keep in mind that the Victoria Line was designed from the outset in the 60s to be a very high-capacity line. The (L) was designed in the 1910s.

Paris line 1 opened for service in 1900, and is on 34 tph after the upgrade.

It's projected to hit 42 tph once all the new rolling stock is deployed.

So it's certainly possible to get contemporary performance from 100 year old lines.

Maybe then, the issue with the L isn't technical... it's money and/or how wisely the system operator spends it. Paris line 1 upgrade cost just $700m. That was new signalling, new rolling stock, and platform edge doors.

Share this post


Link to post
Share on other sites

for the record we are NEVER ALLOWED TO KEY BY A SIGNAL WITHOUT PERMISSION, UNLESS ITS AUTHORIZED KEY BY!

Share this post


Link to post
Share on other sites
14 hours ago, I Run Trains said:

for the record we are NEVER ALLOWED TO KEY BY A SIGNAL WITHOUT PERMISSION, UNLESS ITS AUTHORIZED KEY BY!

That's understandable, but even of someone did, the T/O could clearly see if there was a train in front of them.  

As an example of use, if there is a train stopped half way in the tunnel leaving the station (or fully outside iof the station), why couldn't the next train at least pull the first car ( or more) into the station to let people out instead of waiting an HOUR or so for a "rescue" train?

Share this post


Link to post
Share on other sites
3 hours ago, N6 Limited said:

As an example of use, if there is a train stopped half way in the tunnel leaving the station (or fully outside iof the station), why couldn't the next train at least pull the first car ( or more) into the station to let people out instead of waiting an HOUR or so for a "rescue" train?

They often do exactly that. 

They just are given explicit permission by RCC to do so with "extreme caution and restricted speed"

Share this post


Link to post
Share on other sites
On 6/7/2018 at 12:07 PM, N6 Limited said:

That's understandable, but even of someone did, the T/O could clearly see if there was a train in front of them.  

As an example of use, if there is a train stopped half way in the tunnel leaving the station (or fully outside iof the station), why couldn't the next train at least pull the first car ( or more) into the station to let people out instead of waiting an HOUR or so for a "rescue" train?

Actually One of the rules is If we cannot fully make it into he station we can pull at least the first car in. we can not go half way into the station because they fear that people will attempt to jump off the train between the cars. If there is a situation where another train is stuck, and i can pull at least the first car into the station, i can Key every signal ONLY WITH PERMISSION! 

Share this post


Link to post
Share on other sites
On 6/7/2018 at 3:19 PM, itmaybeokay said:

They often do exactly that. 

They just are given explicit permission by RCC to do so with "extreme caution and restricted speed"

Correct!

  • Thumbs Up 1

Share this post


Link to post
Share on other sites
2 hours ago, I Run Trains said:

Actually One of the rules is If we cannot fully make it into he station we can pull at least the first car in. we can not go half way into the station because they fear that people will attempt to jump off the train between the cars. If there is a situation where another train is stuck, and i can pull at least the first car into the station, i can Key every signal ONLY WITH PERMISSION! 

Hell I've considered doing that between stations even.

Share this post


Link to post
Share on other sites
5 hours ago, I Run Trains said:

Actually One of the rules is If we cannot fully make it into he station we can pull at least the first car in. we can not go half way into the station because they fear that people will attempt to jump off the train between the cars. If there is a situation where another train is stuck, and i can pull at least the first car into the station, i can Key every signal ONLY WITH PERMISSION! 

Keying signals - is that actually exiting the cab and manually turning a key to turn a red green or yellow?

Share this post


Link to post
Share on other sites
22 hours ago, Deucey said:

Keying signals - is that actually exiting the cab and manually turning a key to turn a red green or yellow?

A key by is where the T/O exploits the train stop drive-down feature by pulling close to the signal. The signals were designed so that two red signals (with exceptions) are between a train and its follower, the red signal directly behind the train will have the Trip-arm *DOWN* while the rear-most red will have the Trips *UP*. The Double-Red system was adopted in the IRT days to simplify some complexities such as sorting out how a train could pass a signal, replace it (turn it red) without tripping itself, in the traditional single block method.

Anyway, because the signal and the track circuits are offset from the signals by a few inches a train can pass the insulated joint and occupy the track circuit in advance of the Signal this activates the drive-down feature and lowers the Trip-arm allowing the train to pass. There are also hooks on the roadbed that allow the first T/O to clamp down the Trip-arm so the next train  does not have to inch up to the signal looking for the sweet-spot and can pass at a higher, although still slow speed. 

As far as actual keying I'm not aware of any automatics that still have this feature, although anything is possible I suppose.  On home signals there is a lever where if the signal cannot clear to a normal indication for whatever reason the tower can activate the call-on feature and the T/O would pull up to the signal and turn the lever hanging about a foot in front of the signal (those yellow boxes handing off the double headed signals. 
 

  • Thanks 3
  • Upvote 2

Share this post


Link to post
Share on other sites
13 hours ago, Jsunflyguy said:

A key by is where the T/O exploits the train stop drive-down feature by pulling close to the signal. The signals were designed so that two red signals (with exceptions) are between a train and its follower, the red signal directly behind the train will have the Trip-arm *DOWN* while the rear-most red will have the Trips *UP*. The Double-Red system was adopted in the IRT days to simplify some complexities such as sorting out how a train could pass a signal, replace it (turn it red) without tripping itself, in the traditional single block method.

Anyway, because the signal and the track circuits are offset from the signals by a few inches a train can pass the insulated joint and occupy the track circuit in advance of the Signal this activates the drive-down feature and lowers the Trip-arm allowing the train to pass. There are also hooks on the roadbed that allow the first T/O to clamp down the Trip-arm so the next train  does not have to inch up to the signal looking for the sweet-spot and can pass at a higher, although still slow speed. 

As far as actual keying I'm not aware of any automatics that still have this feature, although anything is possible I suppose.  On home signals there is a lever where if the signal cannot clear to a normal indication for whatever reason the tower can activate the call-on feature and the T/O would pull up to the signal and turn the lever hanging about a foot in front of the signal (those yellow boxes handing off the double headed signals. 
 

179 Lower relay still has the manual release for keying by a automatic signal...

Drives me nuts when i have to go down there for my relay lol...

Share this post


Link to post
Share on other sites
On 4/12/2018 at 9:49 PM, bobtehpanda said:

It's not really an unfinished job. You have to keep in mind that when this CBTC was first conceptualized for the (L) it was not for growing usage, but rather as a test track for the technology. The projections for (L) service requirements never anticipated anything like the rapid gentrification of Williamsburg to ENY occurring. And installing a power system is at best tangentially related to upgrading signalling.

As far as power supply goes, you also have to keep in mind that the Victoria Line was designed from the outset in the 60s to be a very high-capacity line. The (L) was designed in the 1910s.

That is true.  We forget that this was designed over 100 years ago and it's only been in the last 10-15 years that (L) ridership has skyrocketed.

What they SHOULD do once the (L) comes back into Manhattan is have all trains be nine cars since all stations were built to handle eight-car trains of 67' BMT Standards. It would be a tight fit having the edges of nine-car trains just outside the stations (as such would be 540' and the stations are mostly I believe 536'), but nine-car trains on the (L) are likely doable and add capacity without much else needing to be done other than perhaps adding a few feet at 8th Avenue.

Share this post


Link to post
Share on other sites
12 hours ago, RTOMan said:

179 Lower relay still has the manual release for keying by a automatic signal...

Drives me nuts when i have to go down there for my relay lol...

I don't know why they don't get rid of that already. It's only that one and one on the Dyre line, unless it's been replaced already. Will 179th be upgraded as part of the Queens signal project? They installed the manual release because of the wall collision down there years ago, but now with the 10 second delay in keying by, you wouldn't need the lever to make sure you stop all the way.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use.