Red lights on the Green Line

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Re: Red lights on the Green Line

Postby BandM4266 » Thu Jun 20, 2013 8:24 pm

boblothrope wrote:
ExCon90 wrote:Signals timed to control speed are common all over the New York City Subway and PATH, and as TrainManTy commented it is perfectly possible to arrange them so that a train proceeding under control at the prescribed speed will see the signal clear up as it approaches, so that no stop is necessary. Apart from the other considerations mentioned, standing passengers, of whom there are many on the Green Line at all hours, find incessant stops and starts to be very irritating.


These always-stop signals are a big peeve of mine.

If the T cared at all about getting people to their destination with speed and comfort, they'd get rid of them right away. They're a major reason why the Central Subway often has stop-and-go traffic from end to end, even outside rush hour.

People driving on the Mass Pike don't have to deal with the delays and discomfort caused by stop signs. So why should transit riders?

It's a generally accepted road engineering principle that stop signs should not be used for speed control. In fact, the MUTCD expressly prohibits it. And most normal passenger rail systems are designed to keep the trains moving, especially in areas that are a capacity bottleneck (and if the Central Subway isn't one of those, I don't know what is).

I'm also not convinced that all-stop signals increase safety. They encourage drivers to speed between signals. And if drivers are blowing through red lights at grade and station timers, that's a bigger problem which won't be fixed by a stop signal band-aid.

There's also the issue of wasted electricity. Can you imagine how much the meter spins every time a Green Line train accelerates up to speed? Multiply that by the number of daily trips on the Green Line, *and* by the number of all-stop signals in the tunnel, and that's a whole lot of money and energy blowing up the stack.


This is exactly why I stated before that some people need a life! It's a peeve that a signal stops us for 8 seconds in our day! Why can't the T get us there with speed and comfort.
My question is what about safety? Would you rather a train not stop at one of these safety signals and come around a bend that obstructs an operators view and collide with a stopped train ahead? I wouldn't want it to, but all people think of is how to get somewhere faster without a thought to safety!
You explained why stop signs are not to be used for speed control! I don't fully agree about that! There is a at least 1 street that I know of in Lowell that has a stop sign halfway down the hill ( it maybe at an intersection for a small side street but for good reason), it is a good way to check that your brakes are working and that you won't be going down the hill where the road ends at a T intersection and beyond is woods! Well same on the MBTA portals it is a great way of checking that the brakes will operate properly on an incline!
I am not 100% sure about this but aren't the type 7 when in dynamic braking being used as a regenerative motor? Therefore creating power that is returned to the overhead wires to be used to power yet another car? So if so not much energy if any used!
I am open to learning about signal systems and other issues that I don't understand but when someone is complaining about safety vs time and speed that is my peeve
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Re: Red lights on the Green Line

Postby sery2831 » Fri Jun 21, 2013 2:24 am

boblothrope wrote:
ExCon90 wrote:Signals timed to control speed are common all over the New York City Subway and PATH, and as TrainManTy commented it is perfectly possible to arrange them so that a train proceeding under control at the prescribed speed will see the signal clear up as it approaches, so that no stop is necessary. Apart from the other considerations mentioned, standing passengers, of whom there are many on the Green Line at all hours, find incessant stops and starts to be very irritating.


These always-stop signals are a big peeve of mine.

If the T cared at all about getting people to their destination with speed and comfort, they'd get rid of them right away. They're a major reason why the Central Subway often has stop-and-go traffic from end to end, even outside rush hour.


The T cares about safety, that's the priority here.


boblothrope wrote:People driving on the Mass Pike don't have to deal with the delays and discomfort caused by stop signs. So why should transit riders?


Well last I checked the Green Line travels in the city at slow speeds. If we had random stop signals on the Commuter Rail to control speed, you would have a point here.


boblothrope wrote:I'm also not convinced that all-stop signals increase safety. They encourage drivers to speed between signals. And if drivers are blowing through red lights at grade and station timers, that's a bigger problem which won't be fixed by a stop signal band-aid.


First, by design the operators will not be able to achieve a speed that is greater than the limit between the stop signal and the station. And I am not understanding your comment about blowing red lights?
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Re: Red lights on the Green Line

Postby boblothrope » Fri Jun 21, 2013 4:24 pm

BandM4266 wrote:It's a peeve that a signal stops us for 8 seconds in our day! Why can't the T get us there with speed and comfort.
My question is what about safety? Would you rather a train not stop at one of these safety signals and come around a bend that obstructs an operators view and collide with a stopped train ahead?


My point was not about the 8 seconds. It's about the cascading delays which cause stop and go traffic in the entire tunnel, as well as passenger comfort and energy use.

No, I obviously don't want trains running red lights and rear-ending each other. But I don't think pointless stop signals are a good way to prevent that.
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Re: Red lights on the Green Line

Postby BandM4266 » Fri Jun 21, 2013 5:00 pm

boblothrope wrote:
BandM4266 wrote:It's a peeve that a signal stops us for 8 seconds in our day! Why can't the T get us there with speed and comfort.
My question is what about safety? Would you rather a train not stop at one of these safety signals and come around a bend that obstructs an operators view and collide with a stopped train ahead?


My point was not about the 8 seconds. It's about the cascading delays which cause stop and go traffic in the entire tunnel, as well as passenger comfort and energy use.

No, I obviously don't want trains running red lights and rear-ending each other. But I don't think pointless stop signals are a good way to prevent that.


Well between you and the original person that opened the thread that is the way you came across. Granted their maybe some pointless signals here and there but look at the age of the system. They probably didn't need all of these signs/signals but after some events they decided to add them. My guess would be the fact that to actually correct some of the issues would require a tunnel realignment (ex: Boylston -Arlington to reduce the blind curve), which by adding a signal/sign was by far the cheapest way of correcting a problem. I still believe that you can make it from point A to point B faster then if you where to take the bus.
About the energy use I still believe that it is not that bad as I do believe that the braking system is regenerative, rather then burning of the energy created through resistor grids. Someone that knows could correct me if I am wrong !
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Re: Red lights on the Green Line

Postby MBTA3247 » Sat Jun 22, 2013 8:16 pm

The Type 8s I know use dynamic braking (one of the side panels on the roof directly above the end door is labeled as such). Presumably the Type 7s also use dynamics vs regenerative.
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Re: Red lights on the Green Line

Postby Yellowspoon » Sun Jun 23, 2013 6:12 am

BandM4266 wrote: ... I am not 100% sure about this but aren't the type 7 when in dynamic braking being used as a regenerative motor? Therefore creating power that is returned to the overhead wires to be used to power yet another car? So if so not much energy if any used! ...
I am not 100% sure either, but I believe the types 7/8 use dynamic braking which is different from regenerative braking. With dynamic braking the kinetic energy is turned into electric energy and the electric energy is turned into heat with resistors. The electricity is not returned to the power grid because of the complexity of matching voltages and load. In cold weather, this heat could warm the passengers (I don't know if it does). In the summer, it's waste. The advantage of dynamic braking over friction brakes is that dynamic braking saves wear on the friction brakes.
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Re: Red lights on the Green Line

Postby GP40MC 1116 » Sun Jun 23, 2013 12:43 pm

boblothrope wrote:
BandM4266 wrote:It's a peeve that a signal stops us for 8 seconds in our day! Why can't the T get us there with speed and comfort.
My question is what about safety? Would you rather a train not stop at one of these safety signals and come around a bend that obstructs an operators view and collide with a stopped train ahead?


My point was not about the 8 seconds. It's about the cascading delays which cause stop and go traffic in the entire tunnel, as well as passenger comfort and energy use.

No, I obviously don't want trains running red lights and rear-ending each other. But I don't think pointless stop signals are a good way to prevent that.


It's been explained here more than once why the T has stop signals in strategic locations for safety related reasons. Therefore those signals are not "pointless"

If you don't like the 8 seconds delay, go hop in your car and see how much faster it gets you to your destination.
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Re: Red lights on the Green Line

Postby boblothrope » Mon Jun 24, 2013 12:31 pm

GP40MC 1116 wrote:It's been explained here more than once why the T has stop signals in strategic locations for safety related reasons. Therefore those signals are not "pointless"


Do you have crash statistics from before and after the stop signals went in?

I don't, but the general sense I have is that a rear-end accident happens every few years on the Green Line, and this hasn't changed as more and more stop signals are added.

If the safe speed for a stretch of track is 10 mph, make sure the drivers go 10. Not 0 and then 10.

GP40MC 1116 wrote:If you don't like the 8 seconds delay, go hop in your car and see how much faster it gets you to your destination.


I do whatever I can to avoid riding the Green Line. Telling people, "Yeah, riding our transit system is an awful experience, but hey, it's better than driving!" is not the way to improve quality of life in our city.

And please stop with the 8 seconds. I explained how the inefficient throughput of the signal system causes stop-and-go traffic for the length of the tunnel much of the time.
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Re: Red lights on the Green Line

Postby sery2831 » Tue Jun 25, 2013 1:57 am

boblothrope wrote:
GP40MC 1116 wrote:It's been explained here more than once why the T has stop signals in strategic locations for safety related reasons. Therefore those signals are not "pointless"


Do you have crash statistics from before and after the stop signals went in?

I don't, but the general sense I have is that a rear-end accident happens every few years on the Green Line, and this hasn't changed as more and more stop signals are added.


More and more stop signals have been installed? What are the recent additions? I am not aware of these.

boblothrope wrote:If the safe speed for a stretch of track is 10 mph, make sure the drivers go 10. Not 0 and then 10.


As I explained the stop is necessary to make the operator aware on how the train will brake/stop. Every train stops differently, between equipment and passenger load. This is the safest way to make this happen!

boblothrope wrote:And please stop with the 8 seconds. I explained how the inefficient throughput of the signal system causes stop-and-go traffic for the length of the tunnel much of the time.


So station stops do not factor into the stopping and starting?
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Re: Red lights on the Green Line

Postby Disney Guy » Tue Jun 25, 2013 10:37 am

(copied from another post)
One time ca. 1970 I was on a 3 car PCC train going from Boylston to Arlington at speed when the trolley poles of the first two cars went off in succession passing a certain spot and went bumping under the span wires overhead. Shortly thereafter a signal along the way was set to rest as red, and I suspect that is the one that has remained unchanged as red to this day.

I do think that most of these safety stops could be replaced with timing signals. As I recall, trains coming inbound from Science Park stop twice coming to the portal. At least one of these should be replaced with a timing signal.

I cannot dispute that several of these signals each result in an 18 second increase in travel time compared with having a yellow light at that location.

Here's a riddle: Why is there a single red signal before the double red interlock coming inbound in the Boylston St. subway approaching Copley Junction but not on the Huntington Ave. subway inbound approaching the same junction? Compared with single reds before the double red interlocks on both branches at Beacon Junction for the C and D lines inbound.
Last edited by Disney Guy on Tue Jun 25, 2013 4:05 pm, edited 3 times in total.
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Re: Red lights on the Green Line

Postby CRail » Tue Jun 25, 2013 10:52 am

boblothrope wrote:Do you have crash statistics from before and after the stop signals went in? I don't, but the general sense I have is that a rear-end accident happens every few years...and this hasn't changed...

You can't refer to a statistic while explaining you don't have said statistic.

boblothrope wrote:Telling people, "Yeah, riding our transit system is an awful experience, but hey, it's better than driving!" is not the way to improve quality of life in our city.

"Quality of life" is such a BS concept, only used as an excuse to justify a personal opinion towards something as a legitimate issue. Life's "quality" is based entirely on one's attitude which is controlled from within. It cannot and should not be put on one's environment to fix what only can be fixed by self control. Plus, it's all relative. Talk to the people who have been involved in the collisions which occurred, and see what they say about a safety measure's impact on their "quality of life."

To be honest, I think the safety stops are unnecessary too. As I've explained, think there are better ways. Simply eliminating the stops, however, is not one of them.

boblothrope wrote:And please stop with the 8 seconds. I explained how the inefficient throughput of the signal system causes stop-and-go traffic for the length of the tunnel much of the time.

I've never experienced this. What causes congestion in the central subway is dwell times tied with speed restrictions. Safety stops certainly don't improve the situation, but they also certainly don't cause it.
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Re: Red lights on the Green Line

Postby newpylong » Tue Jun 25, 2013 10:56 am

How about the outbound stop signal between Boylston and Arlington on the hill? Isn't that to prevent a fully loaded trolley from not being able to stop going into Arlington? How about they reduce the speed limit of the track leading up to the station instead of stopping? It doesn't seem like the only avoidable stop signal to me...
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Re: Red lights on the Green Line

Postby CRail » Tue Jun 25, 2013 11:58 am

The theory is if your brakes have failed, you have more time to figure out what to do than if you realize your brakes failed 50 feet away from the car ahead of you, or even closer to a sharp curve. It's not for speed control, it's to ensure the operator still has control.
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Re: Red lights on the Green Line

Postby sery2831 » Tue Jun 25, 2013 1:08 pm

CRail wrote:The theory is if your brakes have failed, you have more time to figure out what to do than if you realize your brakes failed 50 feet away from the car ahead of you, or even closer to a sharp curve. It's not for speed control, it's to ensure the operator still has control.


THIRD time this was explained in this thread!
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Re: Red lights on the Green Line

Postby newpylong » Tue Jun 25, 2013 2:48 pm

A slower speed limit makes more operational sense to me, unless, as indicated by another poster that motormen are not trusted. What is the difference between making that stretch 20 mph instead of 40 mph with a stop in the middle? They are going to crank it back up to 40 after the stop right up to Arlington anyway...

Does central get something on the board when those signals are passed without permission or when they aren't showing a permissive signal?
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