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overclocked

Subway curves

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I didn't want to wake up the old thread, so here goes nothing

 

I always wondered why there are so many track curves in the New York City subway system? Correct me if I am wrong, but aren't those curves a limiting factor for average trains speed, which results in lower number of trains per hour?

If the city would build the subway today from scratch, would it be able/want to avoid having so much curves? So, what was limiting the early subway builders from building the truly rapid system? Were those the rights of land owners, the costs, difficulty of construction or some other causes of which I am not aware?

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I didn't want to wake up the old thread, so here goes nothing

 

I always wondered why there are so many track curves in the New York City subway system? Correct me if I am wrong, but aren't those curves a limiting factor for average trains speed, which results in lower number of trains per hour?

If the city would build the subway today from scratch, would it be able/want to avoid having so much curves? So, what was limiting the early subway builders from building the truly rapid system? Were those the rights of land owners, the costs, difficulty of construction or some other causes of which I am not aware?

 

Subway tracks follow the street. So if the street turns so does the line, and also the line would turn when it wants to switch to another destination. This is why there are so many turns in the subway, and no you can't build a subway without turns to bring people to their destination. Also again with the need for speed it isn't needed. We have express service, and we don't need faster since this is a subway not a high speed railroad.

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Subway tracks follow the street. So if the street turns so does the line, and also the line would turn when it wants to switch to another destination. This is why there are so many turns in the subway, and no you can't build a subway without turns to bring people to their destination. Also again with the need for speed it isn't needed. We have express service, and we don't need faster since this is a subway not a high speed railroad.

 

So basically we are limited to the 1811 grid design?

I agree that the subway without turns is impossible, but some early lines have curves that are worse then others, like BMT Broadway south of City Hall all the way to DeKalb Av.

I don't mean to offend, but I don't believe express service is faster, I see it as a cheaper way to bring more subway service and to relieve the crowding on those narrow platforms. In my opinion speed is an important factor for Rapid transit, which determines how many people it can serve. I would like to know is the curvature of Canarcie line is the limiting factors of TPH or there are other causes like lack of trains?

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So basically we are limited to the 1811 grid design?

I agree that the subway without turns is impossible, but some early lines have curves that are worse then others, like BMT Broadway south of City Hall all the way to DeKalb Av.

I don't mean to offend, but I don't believe express service is faster, I see it as a cheaper way to bring more subway service and to relieve the crowding on those narrow platforms. In my opinion speed is an important factor for Rapid transit, which determines how many people it can serve. I would like to know is the curvature of Canarsie line is the limiting factors of TPH or there are other causes like lack of trains?

 

The subway also has a lot of turns to avoid buildings as well. The Canarsie Line runs through several important buildings and so would need those curves so it won't harm them, and it is also needed for engineering reasons. Also it isn't curves that affect train service. What does is the signals, how many trains are available, how many trains are out, and the availability of transit workers that could operate the trains that determines TPH factor.

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The subway also has a lot of turns to avoid buildings as well. The Canarsie Line runs through several important buildings and so would need those curves so it won't harm them, and it is also needed for engineering reasons. Also it isn't curves that affect train service. What does is the signals, how many trains are available, how many trains are out, and the availability of transit workers that could operate the trains that determines TPH factor.

 

Thanks for clearing up the whole Canarcie business for me.

I don't see any real engineering reasons for why the Canarcie was built the way it was. It could have been built deeper or could have been moved. All the issues which I see as financial and political, but not engineering.

I can be wrong but all the other issues regarding TPH are fixable unlike the sharp turns at which no matter, all the trains have to slow down.

 

Or I am just spoiled by the subway systems which Soviets built for us;)

Afterall I grew up riding them.

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The Canarsie line is a mess because it was built in bits and pieces dating all the way back to the earlier Brooklyn elevateds to the middle of the 20th century.

 

As time went on planners learned from their mistakes and made the systems faster. That's why the IND has no grade crossings (the IRT has one at 142nd st junction and the BMT has one at Myrtle Junction) - all flying junctions, and why the tracks are generally straighter on those lines to permit higher operating speeds.

 

However in some cases you are limited by the terrain and geography of New York City. Taller buildings have deep foundations which must be worked around, etc. Likewise placement of entrances has to be compatible with the station planned below, which got easier once stations started including mezzanine levels, but when they didn't, sometimes curves were necessary.

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The Canarsie line is a mess because it was built in bits and pieces dating all the way back to the earlier Brooklyn elevateds to the middle of the 20th century.

 

As time went on planners learned from their mistakes and made the systems faster. That's why the IND has no grade crossings (the IRT has one at 142nd st junction and the BMT has one at Myrtle Junction) - all flying junctions, and why the tracks are generally straighter on those lines to permit higher operating speeds.

 

However in some cases you are limited by the terrain and geography of New York City. Taller buildings have deep foundations which must be worked around, etc. Likewise placement of entrances has to be compatible with the station planned below, which got easier once stations started including mezzanine levels, but when they didn't, sometimes curves were necessary.

 

Thank you, I had thought that newer lines were more thought through as they were built.

 

As a separate question why the majority subway wasn't build using "deep bore" methods, which would avoid the conflict with the buildings owners? High costs and low benefits? As the example to deep bore is IRT Fort George Tunnel under Washington heights.

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Thank you, I had thought that newer lines were more thought through as they were built.

 

As a separate question why the majority subway wasn't build using "deep bore" methods, which would avoid the conflict with the buildings owners? High costs and low benefits? As the example to deep bore is IRT Fort George Tunnel under Washington heights.

 

At the time the subway was being built the equipment for that wasn't in existence yet. The New York City Subway was built using the cut and cover method, and is radically different from most metro systems around the world.

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At the time the subway was being built the equipment for that wasn't in existence yet. The New York City Subway was built using the cut and cover method, and is radically different from most metro systems around the world.

 

The London Underground is older and deeper than the nyc subway, but london isnt built on solid bedrock as nyc is.

 

joe

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The London Underground is older and deeper than the NYC subway, but London isn't built on solid bedrock as NYC is.

 

Joe

 

I covered that in engineering difficulties as well. One of the many reasons why the Second Avenue Subway (Q)(T) is taking so long.

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As well as many of the other projects around. Using the available features or small connections have deemed easier than brand new builds. I doubt they would be building SAS if those tunnel portions on the UES weren't already there. Even still, I think below 63rd is still a myth as that is 100% new construction (even though there are a few station shells downtown as we all know).

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one thingwe all are missing is we do not at all spend the money and use the innovations as other counties, we are stuck on the line as far as construction and new ways of doing things we also dont have the support, people here dont like being inconveniced at all and if you put money in the way we will not ever get on the lever as other counties are on japan, London, Germany,

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Arguably the main reason for the curves is simply the city bedrock. The stone we've got below ground is structurally essential to the streets above and is incredibly difficult to move. The PATH, for example, the main reason it curves so much instead of going straight west to NJ is due to the rock below ground. When it was built, around the era of some of the subway lines, there was no technology to go through that type of rock, and it's too late today with the developments and buildings above.

 

Thank you, the much anticipated explanation is here.

 

Here we go again, "everyone else does blah blah and we don't".

 

We have the most advanced subway system in the world, every other system built after it is oboslite and should be rebuilt to OUR standards.

 

Why? Becuase we have EXPRESS TRACKS and a lot of them.

 

Let the MTA finish the CBTCRF-ATO system, and we'd be even more advanced.

 

So being cheap and providing extra service without digging another set of tunnels is advanced? It's smart at best and I wish no other country/city to have a redicule of "express" subway. The way I see this, express subway service is the sole priviledge of the New York City, because the service from the outer boroughs centers on the relatively narrow island of Manhattan, which physically can not hold all of the unwinded routes. Thus to bring all of the service(except Cross-Town) to Manhattan, both economic and practical solution was born; the express tracks. They do not slow down the other, local, lines and help relieve the crowds on the platforms. On other hand it reduces the surface area that otherwise two or more lines would be served by subway. It also creates bottlenecks when two trains from two lines switch to the single track.

E.g. downtown (:P and (D) trains arrive at the same time at 59th street, now one of the trains has to wait until the other clears, so if (D) goes ahead, the (:( stays. Assuming there is a downtown (C) train approaching 59th, since local track is occupied the (C) can't go further and has to stop in the tunnel.

If all the lines would be separate, this setting above would not ever happen.

 

At last where did you see the bashing, all I wanted to know what was the purpose of having so many curves in the system. I gave the example so the people would know where I'm coming from to answer it correctly, and they did.

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So being cheap and providing extra service without digging another set of tunnels is advanced? It's smart at best and I wish no other country/city to have a redicule of "express" subway. The way I see this, express subway service is the sole priviledge of the New York City, because the service from the outer boroughs centers on the relatively narrow island of Manhattan, which physically can not hold all of the unwinded routes. Thus to bring all of the service(except Cross-Town) to Manhattan, both economic and practical solution was born; the express tracks. They do not slow down the other, local, lines and help relieve the crowds on the platforms. On other hand it reduces the surface area that otherwise two or more lines would be served by subway. It also creates bottlenecks when two trains from two lines switch to the single track.

E.g. downtown (:P and (D) trains arrive at the same time at 59th street, now one of the trains has to wait until the other clears, so if (D) goes ahead, the (:( stays. Assuming there is a downtown (C) train approaching 59th, since local track is occupied the (C) can't go further and has to stop in the tunnel.

If all the lines would be separate, this setting above would not ever happen.

 

At last where did you see the bashing, all I wanted to know what was the purpose of having so many curves in the system. I gave the example so the people would know where I'm coming from to answer it correctly, and they did.

 

He was talking to Chris not you.

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Here we go again, "everyone else does blah blah and we don't".

 

We have the most advanced subway system in the world, every other system built after it is oboslite and should be rebuilt to OUR standards.

 

Why? Becuase we have EXPRESS TRACKS and a lot of them.

 

Let the MTA finish the CBTCRF-ATO system, and we'd be even more advanced.

The smartest thing I see is redundancy, which we are seeing less of now compared to when subway construction first started (refer to the reduction of 72 Street from a 3-tracked station to a 2-tracked station). When I rode the trains much more frequently than today (back when the (Mx) and (R) still ran together)), trains would sometimes get stuck going down 4 Avenue during PM rush. The entire express track would be backed up while the locals zoomed by (or the other way around).

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The original subways were planned to serve large numbers of people. However moving large numbers of people into and out of very deep stations requires the use of elevators or escalators. Think about the IRT subway stations at 168th Street, or 191st Street, or 190th Street on the A-line. There is just no way that most folks are going to walk 10 flights of stairs to reach the subway trains each and every day.

 

Building the stations closer to the surface allows much easier access to the stations and their platforms. The subways generally follow the streets because the streets are public property - just think about the ease of acquiring the property and property rights (easements, etc) for all of the land that the subways and their elevated lines use - especially in the core of the city that was well developed when the subways were built.

 

Ever wonder about Seventh Avenue South, and just how that street was built? It did not exist until the Seventh Avenue IRT subway was built - requiring an removal all of the buildings, commercial buildings, homes, and other structures in building that section of that subway line. Big bucks had to be paid to many many property owners, many families had to be relocated, etc. None of that is cheap.

 

Just building the subways and stations in many places required knitting the stations and tunnels among various basements, water tunnels, sewers, and other features underground. Building the subways was often damaging enough (to people, buildings, shops, commerce, etc.)

 

In addition the subways were created as replacements for the trolley and omnibus lines that criss-crossed the city about 100 years ago, as well as in several cases, replacements for the elevated lines. In addition at the time of the first IRT subway there were no "electric companies" - they had to build and operate their own electric power generators, and various electric sub-stations. The original power plant for the IRT subways was located at the Lenox Terminal train yard, the current home terminal of the #3 line.

 

For the early subway builders, there were a lot of things to consider. Look up the history about the building of the subway lines. It is fascinating.

 

Mike

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The original subways were planned to serve large numbers of people. However moving large numbers of people into and out of very deep stations requires the use of elevators or escalators. Think about the IRT subway stations at 168th Street, or 191st Street, or 190th Street on the A-line. There is just no way that most folks are going to walk 10 flights of stairs to reach the subway trains each and every day.

 

Building the stations closer to the surface allows much easier access to the stations and their platforms. The subways generally follow the streets because the streets are public property - just think about the ease of acquiring the property and property rights (easements, etc) for all of the land that the subways and their elevated lines use - especially in the core of the city that was well developed when the subways were built.

 

Ever wonder about Seventh Avenue South, and just how that street was built? It did not exist until the Seventh Avenue IRT subway was built - requiring an removal all of the buildings, commercial buildings, homes, and other structures in building that section of that subway line. Big bucks had to be paid to many many property owners, many families had to be relocated, etc. None of that is cheap.

 

Just building the subways and stations in many places required knitting the stations and tunnels among various basements, water tunnels, sewers, and other features underground. Building the subways was often damaging enough (to people, buildings, shops, commerce, etc.)

 

In addition the subways were created as replacements for the trolley and omnibus lines that criss-crossed the city about 100 years ago, as well as in several cases, replacements for the elevated lines. In addition at the time of the first IRT subway there were no "electric companies" - they had to build and operate their own electric power generators, and various electric sub-stations. The original power plant for the IRT subways was located at the Lenox Terminal train yard, the current home terminal of the #3 line.

 

For the early subway builders, there were a lot of things to consider. Look up the history about the building of the subway lines. It is fascinating.

 

Mike

 

Thanks MikeGerald, I was hoping you would look into the thread and help me out, and you did it. Thanks. One thing I failed to realize was that back home the deep stations are served by the long escalators, a feature that wasn't yet available in early XX century(and space consuming too). I came to the conclusion that elevators can not efficiently move people in and out of the station. Would I be wrong to say that the deep stations in NYC were/are not liked by the most?

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When we look at the outer boroughs, we must take into account geography as a factor as to why the subway lines are curved. For example, the Pelham Line in the Bronx is very curvy because it must match the shape of the Bronx's peninsula. Otherwise, it would just cut a diagonal across the borough and not outline its southern end. Many neighborhoods would be isolated if the Pelham Line cut a straight diagonal.

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Personally, I think it's better for a subway line to be curved as opposed to straight. IMO, if a line is straight, it doesn't serve as many people. It seems to me that straight lines are been built at the engineer's convenience and not in the public's interest.

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Personally, I think it's better for a subway line to be curved as opposed to straight. IMO, if a line is straight, it doesn't serve as many people. It seems to me that straight lines are been built at the engineer's convenience and not in the public's interest.

The key is balance and efficiency. To maximize utility, lines ideally curve at every possible opportunity to connect the most populated points. To maximize speed, lines should ideally be straight with connecting perpendicular lines to move people in the other direction. Somewhere between the two lies an acceptable plan.

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From an engineering and operations and operations planning perspective, routes should be slightly curved so as to facilitate properly serving neighborhoods with service patterns that reflect appropriate ridership patterns from areas of high population density to areas of high ridership demand.

 

However, the curves should not be so pronounced as to require significant reduction of operating speeds along the route. Station platforms, where possible, should be straight for increased visibility and customer safety. Flying junctions should be used at all times when crossing trains in service, as grade crossings for this purpose are cumbersome and slow. Switches should be provided periodically allowing for moves in all directions on all tracks. Sidings should exist for temporary storage of trains (ie work trains, when a revenue train must pass) but are not required for revenue service.

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Switches should be provided periodically allowing for moves in all directions on all tracks.

For turning back trains in the case of an emergency or construction, if I may add. And if possible, the default path of the trains should be as straight as possible so the tunnel or elevated structure should widen gradually well before any sidings in the middle.

 

Lines should also have a minimum of 3 tracks just like the lines built a century ago. Seeing how construction on the (L) and (G) is done is enough to justify such a configuration.

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