General MBTA Topics (Multi Modal, Budget, MassDOT)

[F-Line to Dudley]

Re: Driven By Customer 'Service' Parte Dos

Because Paris put in a system that allows 85 second headways, which is an order better than any other state of the art system in the US...

....and thats still less than what you can do on the green line today. So yes, a downgrade.

Best youll find in north america, btw is 90 seconds in mexico City. I dont believe any signalling system in the US does better than every 3 minutes, although please correct me on that.

Lincoln tunnel, we're talking vehicle capacity for signals, not passengers. 700 vehicles.

And the Lincoln tunnel handles over 30,000 in the peak hour, as the buses carry on average 45 passengers each. So 50% more than what the green line is doing....



Find me a signalling system that lets the green line what it does today, that is, have a train enter the station simultaneously as another departs, like a bus can do. No signalling system will let two green line trains park inches apart in park st and load simultaneously.

What part of the system is designed for the headways you want it to have is so hard to grasp about this?

Want trains that can inch behind each other? Program the system to enforce a pause outside the occupied platform, then give the operator cart blanche to inch in as close as they need to capped at no more than 5 MPH. In other words...exactly what the employee handbook says they should be doing today. They can bump, but it's below the speed threshold that'll cause car damage or cause multiple injuries onboard. This Boylston crash was clocked at 2 to 2-1/2 times faster. Speed is the problem here, not proximity. Light rail is fundamentally different from heavy rail or RR's in that there's a lot more leeway on proximity. Different modes for different purposes.

There are well-designed PTC systems and there are poorly-designed PTC systems. But the one truism is that they have to be "designed" to task. That hasn't been done here yet, so neither the utopian nor the dystopian projections fit. It'll do whatever the traffic engineers tell it to do. And, yes, when it's designed with gaping flaws (hint: SEPTA's CBTC will be the most oft-cited on the FAIL end of the scale...but that's a whole other post) you get garbage-in/garbage-out. It's a good/bad engineering sliding scale, not a question of good/bad tech.

What's not clear is if the T even wants to get far enough to let the engineers tell them. If they're indicting the tech this early in the game, that's a decent leading indicator that the leadership isn't interested in solving--much less contemplating--a problem and are just fishing for narrative-fitting ammo.

This is silly.

We had two crashes within a few years of each other. It's called a statistical anomaly. Nothing's changed in the system that I know of that would make it the beginning of a trend. The Green Line's been running for a long time without PTC, and it will continue to run for a long time without PTC. Yeah, someone died. He was texting while driving a fucking train. They cracked down and it's unlikely to happen again. $700m is a ton of money that could be better spent elsewhere. The cost benefit isn't even close.

Ah, I see the last couple pages where you were kinda sorta beginning to entertain the notion of this being a complex issue that didn't fit a neat and tidy political narrative just kind of went out the window there, and you're back to doubling-down on talking points. At least you're being honest with yourself now.

The MassDOT board does not agree with you, BTW, since they copped in the article to being afraid of sanctions for not closing up the safety hole.

 

[massmotorist]

Re: Driven By Customer 'Service' Parte Dos

Ah, I see the last couple pages where you were kinda sorta beginning to entertain the notion of this being a complex issue that didn't fit a neat and tidy political narrative just kind of went out the window there, and you're back to doubling-down on talking points. At least you're being honest with yourself now.

The MassDOT board does not agree with you, BTW, since they copped in the article to being afraid of sanctions for not closing up the safety hole.

When I put more thought into something, or the facts change, so do my opinions. You said it was $327 million. It's now $700 million. And it just seems really silly to spend that much money on something that will keep operations/headways the same at best, and more likely degrade/roll back service, all in the interest of preventing very rare accidents.

But how rare are those accidents? We all remember the last two, but when was the last one before that? Serious question, because I don't know. But based on the information at hand, the cost-benefit on this strikes me as at least 10 times worse then the widely derided NHTSA backup camera rulemaking.

The MassDOT board can think what they want. I don't have a strong opinion about them or their governance (though it strikes me as kind of silly to have a board in the first place). But didn't the article say that they were the ones who "rebuffed recommendations" to approve the funding?

By the way - from NHTSA's own report:

Governmental Oversight of MBTA

Federal Transit Administration

A part of the DOT, the Federal Transit Administration (FTA) administers funding to
public transportation systems throughout the Unites States. Unlike administrations within the
DOT whose authority stems from the Constitution’s Interstate Commerce Clause, the FTA was
authorized using the General Welfare Clause. It therefore received from Congress no regulatory
authority. Title 49 United States Code Section 5334(b) specifically prohibits the secretary of
transportation from regulating the operation, routes, or schedules of a public transportation
system.

The primary enforcement mechanism available to the FTA is the ability to withhold
Federal funds from states that do not comply with the terms and conditions of its Federal
assistance agreement. In response to passage of the Intermodal Surface Transportation Efficiency
Act of 1991, the FTA implemented the State Safety Oversight Program, which placed the
responsibility for rail transit safety on the states maintaining public transit systems. The FTA has
established minimum safety requirements that all states and rail transit agencies must adhere to
in order to receive Federal funding. These requirements address the techniques that are to be
used to conduct inspections and testing, the required maintenance audits and inspection
programs, and the procedures to be used for employee training and certification.

Massachusetts Department of Public Utilities

The MBTA is subject to oversight by the FTA through the offices of the Massachusetts
Department of Public Utilities Transportation Oversight Division, which has developed and
implemented a System Safety Program Plan comprising 21 safety elements defined in Title 49
Code of Federal Regulations Part 659. The MBTA’s safety department is responsible for an
annual internal audit of compliance with a portion of the plan elements so that over a 3-year
period, compliance with all 21 elements will have been audited. The results of these audits are
provided as annual reports to the Department of Public Utilities.

The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, highway, marine, pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The NTSB makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and statistical reviews.

 

[omaja]

Re: Driven By Customer 'Service' Parte Dos

Lincoln tunnel, we're talking vehicle capacity for signals, not passengers. 700 vehicles.

And the Lincoln tunnel handles over 30,000 in the peak hour, as the buses carry on average 45 passengers each. So 50% more than what the green line is doing....

Vehicle throughput is irrelevant since one dispatch on the Green Line holds more than 10x the amount of people on one bus. Think about it this way: the Lincoln Tunnel only carries 50% more passengers but has to do so by making 1800+% more dispatches. Not exactly a model for efficiency.

But whatever the difference between the two, we're talking about the Green Line with its current technology. With moving blocks you'll be able to have more trains use current track real estate. Combine this with expanded three-car train operations and the Green Line could easily see a very dramatic increase in capacity.

Safety and avoiding $500K+ fender benders is obviously priority one, but the simple fact is the Green Line is not optimized to handle current traffic, let alone the annual increases it is seeing. There are two priorities for CBTC: safety and operational efficiency.

Find me a signalling system that lets the green line what it does today, that is, have a train enter the station simultaneously as another departs, like a bus can do. No signalling system will let two green line trains park inches apart in park st and load simultaneously.

CBTC can easily be set up for this type of operation. As Matthew pointed out, the RER effectively allows trains to do this already (if they were short enough, but since one occupies the whole platform, the second train has to be content with waiting a few seconds to enter): http://www.youtube.com/watch?v=1Hx3M_zSFaw.

When I put more thought into something, or the facts change, so do my opinions. You said it was $327 million. It's now $700 million. And it just seems really silly to spend that much money on something that will keep operations/headways the same at best, and more likely degrade/roll back service, all in the interest of preventing very rare accidents.

We're talking about a system that moves nearly the same amount of people as the Red Line per day. The Green Line is over 30 percent of the T's rapid transit ridership. That is a large segment of its operations to just ignore into oblivion. CBTC would improve operations by allowing for decreased headways and increasing the number of trains that can safely and efficiently operate. All the while we have the satisfaction of knowing that there's more than just one person's reflexes that can stop a really bad accident from happening.

Yes, it will cost money; but honestly what can we expect when they've deferred any sort of real maintenance or upgrades to technology and operations for God knows how long? The solution isn't to continue with the status quo until the whole thing fails completely. The number of delays because of switch problems, disabled trains, headway adjustments and the like are pretty common and only seem to become even more common and disruptive with each passing day.

 

[massmotorist]

Re: Driven By Customer 'Service' Parte Dos

We're talking about a system that moves nearly the same amount of people as the Red Line per day. The Green Line is over 30 percent of the T's rapid transit ridership. That is a large segment of its operations to just ignore into oblivion. CBTC would improve operations by allowing for decreased headways and increasing the number of trains that can safely and efficiently operate. All the while we have the satisfaction of knowing that there's more than just one person's reflexes that can stop a really bad accident from happening.

Yes, it will cost money; but honestly what can we expect when they've deferred any sort of real maintenance or upgrades to technology and operations for God knows how long? The solution isn't to continue with the status quo until the whole thing fails completely. The number of delays because of switch problems, disabled trains, headway adjustments and the like are pretty common and only seem to become even more common and disruptive with each passing day.

The MBTA itself says that it will increase headways. If they're saying that, it sure as hell won't decrease them.

Cost: $700 million. Less frequent trains
Benefit: Less accidents?

I agree with your statements about switch problems and disabled trains. And those are things whose state of repair and maintenance will continue to degrade if $700m is wasted on a system to prevent minor accidents that occur rarely.

 

[statler]

Re: Driven By Customer 'Service' Parte Dos

Is the T self(state) insured or do they carry private insurance to cover accidents like this. I think that would play a big role in determining if the $700M is cost effective.

 

[omaja]

Re: Driven By Customer 'Service' Parte Dos

The MBTA itself says that it will increase headways. If they're saying that, it sure as hell won't decrease them.

Cost: $700 million. Less frequent trains
Benefit: Less accidents?

I agree with your statements about switch problems and disabled trains. And those are things whose state of repair and maintenance will continue to degrade if $700m is wasted on a system to prevent minor accidents that occur rarely.

If you would read what F-Line has written at least two or three times now, you wouldn't be repeating the same thing over and over again. Yes, if they simply dump the current block setup into the new system, it would result in a decrease in throughput because the current system is not optimized for CBTC. Installing CBTC would allow them to rework the whole traffic engineering scheme to allow for increased capacity.

I don't understand how this is so difficult to understand. We're not going to see different results in Boston where everywhere else has seen capacity and operational increases. That one-off quote from a Wicked Local article was taken entirely out of context and isn't a good substitute for actual research and case studies from systems were CBTC has been implemented.

 

[novitiate]

Re: Driven By Customer 'Service' Parte Dos

If you would read what F-Line has written at least two or three times now, you wouldn't be repeating the same thing over and over again. Yes, if they simply dump the current block setup into the new system, it would result in a decrease in throughput because the current system is not optimized for CBTC. Installing CBTC would allow them to rework the whole traffic engineering scheme to allow for increased capacity.

I don't understand how this is so difficult to understand. We're not going to see different results in Boston where everywhere else has seen capacity and operational increases. That one-off quote from a Wicked Local article was taken entirely out of context and isn't a good substitute for actual research and case studies from systems were CBTC has been implemented.

But everyone else hasn't (see SEPTA for the obvious mistake), only certain systems that implemented things correctly. And even F-Line's posts seem to say that the MBTA has a history of botching these kinds of things (red line).

I don't think massmotorist's analysis is too far off, honestly.

 

[omaja]

Re: Driven By Customer 'Service' Parte Dos

I'm not familiar with the folly's of SEPTA's installation, but this is some interesting reading on the subject: San Francisco's CBA on CBTC.

http://www.fta.dot.gov/documents/CB...26-7005_2010_01_-_101025_final_draft1_(3).pdf

All in all: their primary CBA assumes fewer trains operated (and, thus, slightly higher wait times) and provides a NPV of $395 million over 30 years. Their secondary analysis concludes that CBTC provides a NPV of $300+ million based on decreased costs related to maintenance and operations, and decreased travel/wait times.

 

[F-Line to Dudley]

Re: Driven By Customer 'Service' Parte Dos

SEPTA is the poster child for doing this stupidly. But just by listing what they did stupidly it's easy to see how hard it would be to replicate their stupidity. SEPTA were high achievers to hit their levels of stupidity.


SEPTA light rail is very similar to the Green Line...streetcar feeders into a central subway. Their signal system was fixed blocks, stoplight-style wayside signals, human-controlled dispatching just like the Green Line. Their wayside signals were controlled through track circuits, which are magnetic pulses through the running rails...the signals change by reading the magnetic pulses. Just like Green.


Mistake #1: SEPTA just fed its block layout into the computer and didn't attempt to traffic engineer it. So of course the headways suffered. Case in point: know how on GL outbound every car has to stop at that red light between Boylston and Arlington right next to the old Boylston incline/re-railer work car storage pit? That's because the roof dips low there and the operator can only see a few feet ahead, so there's always a line-of-sight safety pause. Those aren't needed with automation, but the rest of the blocks are spaced for traffic flow around that pause...so, if we kept the blocks the CBTC would have to make every train stop there too. Silly, no?

Mistake #2: SEPTA didn't even replace its old block signals. It kept them live and unmodified rather than design the CBTC with a fail-safe mode. That means their operators have to obey both the computer and the old wayside signals. Say it's late at night and there isn't another train ahead of you for 3 or 4 stations. So what if the computer says it's full speed ahead...if there's a single wayside signal cycling through a yellow or red in the middle of that empty tunnel, they gotta stop for it. So not only do the operators have to watch twice as many signals and be even more hands-on than they were before, if the signals don't agree with each other they're forced to default to whichever one says "STOP" or "SLOW". This maimed their capacity moreso than #1. And increased maintenance cost a hell of a lot because they now have two systems and twice as much hardware to maintain.

Mistake #3: Even though every goddamn line on their system was powered by tried-and-true track circuits, SEPTA decided to use radio/GPS for its CBTC. In a subway, where maintaining radio reception is hard. So when deploying it they of course found dropouts everywhere around curves where the reception line-of-sight got broken, and had to spend for more RF repeaters to keep the system from dumping into safe mode when it lost reception. The end result was they managed to cobble together unbroken reception with enough repeaters, but it was shitty/static-filled reception at a lower data bandwidth. The whole point of CBTC is instantaneous 2-way communication between signals and train, so the extra network latency made that communication less-than-instantaneous. Meaning, trains couldn't be spaced as close because every command had to be safety-buffered for slow communication. The engineers warned them about this. Anybody with a cell phone could've warned them about this. But they went with the wireless bid anyway because GPS was 'something shiny'. There's rumors that the companies pitching the wireless tech may have been 'persuasive' to the board in other ways that got them adopting it over objections, but that was never proven.

Mistake #4: So you've got this wireless hi-tech solution with serious latency issues. And it's got to coexist with the old signal system fired by good ol' instantaneous track circuits. So what happens when the track circuits beat the garbled wireless reception to the punch? Conflicts galore between the two dueling signal systems. Meaning, they had to cut capacity even more to fudge the timing difference between the two systems.

Mistake #5: All of this was such a noose on on-time scheduling that they decided to make the CBTC extra-permissive for operator override. Basically, in most situations as long as they got under 8 MPH they were allowed discretion to ignore signals and inch on line-of-sight. That's a feature, not a bug for light rail...light rail is supposed to be more permissive. Unfortunately, they were under so much pressure to improve schedule-keeping that overrides became standard operating procedure. Meaning, operators got so used to plowing through on override that they got inattentive...they just leaned on the accelerator knowing the enforced speed limit would keep them out of trouble and waited for their own reflexes to deliver them to the platform on-time. Result: *BANG*...they started having (benign) rear-enders again, which made a lot of commuters very angry when this whole debacle was supposed to prevent it. They got chastised for allowing 8 MPH override instead of the 5 MPH standard most older cab signal systems (Red/Orange) allow, and for not forcing an auto-pause as "Are you sure? Yes/No?"-type reminder for the operators before starting override mode. The system became a crutch to condition more lazy human behavior by gaming the system. Regulators, shockingly, have a little bit of a problem with this.


Now, after all the damage has been done, they're finally considering some infrastructure upgrades to double up the dueling signal systems on the same track circuits and do enough nip-and-tuck engineering to eliminate the conflict points. But they long ago conceded that they're not interested in re-increasing headways, so they're not doing a lot of self-reflection on the lack of traffic engineering or the new bad habits their operators picked up (although I think they have made the manual override a little less pointlessly over-permissive).



These things will never ever happen if the T adopts CBTC, simply because its track engineering dept. is not staffed by idiots. SEPTA has a historically bad reputation for making skin-deep traffic engineering decisions and throwing shit at the wall on engineering schematics. So bad that vote after vote has been proposed in Pennsylvania to fragment the agency (esp. the commuter rail division) by mode because they habitually misunderstand basic things about train operation or traffic characteristics of each mode. I wouldn't trust the T to design a station or public space cleanly and without excess or mission creep, and their personnel decisions are habitually suspect. But they have a very good track engineering dept. and the rare times they actually get to spend money doing something forward-thinking with their own track infrastructure they execute the meat-and-potatoes well. BRT, because it's virtually undefined as a unique mode and thus extra-susceptible to "too many chefs" syndrome, is the only mode where committee politics and the pursuit of shiny things has really led them to make a lot of unforced traffic engineering errors.

It's reasonable to assume that for any Green Line CBTC:

-- It will be track circuit-based. None of this wireless BS.
-- It will replace the waysides (probably with a few years of coexistence during deployment). All of the current signal equipment is some distance through its rated 25-30 year lifespan. Stuff like wholesale replacement of all of the D line's signals are already unfunded mandates on the Cap Improvements plan. If replacement's a sunk cost, you displace the current system, not augment. Otherwise you're on the hook for paying for the same thing twice over 25 years. It's breathtaking even SEPTA was so stupid as to miss that point.
-- The replacement will involve less track hardware than what came before it. There's language about this in the individual unfunded mandate line items in the System Maint. chapters of the Cap Improvements plan. Stuff about "disabling unused switches", auditing their track charts to log all this stuff better. Even the CBTC-on-Blue study item...that's all about retiring the hundreds of mechanical trip arms, trip arm heaters, and unnecessary wayside signals. Very clear directives here...simplify and standardize what's out in the field so it gets easier, not harder, for the track gangs to stay on top of maintenance.
-- It will be centrally controlled. They don't want field offices or armies of dispatchers. Every signal project they've initiated in the last 15 years--Orange ATO, Fitchburg Line replacement, one-man ops on Red/Orange, giving CSX 9 figures to go away so they could bring Worcester Line dispatching in-house, even the collective bus GPS initiatives taken as a whole--are all designed to centralize more and more power in that Central Ops command room. Just like Charlie centralizes the fare system and the security cam era centralizes security. While I have no doubt the middle managers will find every way they can to pervert this into requiring more inspectors or more staff...the pull of gravity in the agency has been to get the oversight out of the field and into the command bunker. When you look at the money they've spent on other projects to further that goal, and the fact that Green Line signaling is one of the toughest remaining nuts to crack for centralizing ops...this isn't out-of-line at all with the agency's M.O.



Now, whether the board wants to do anything or is just fishing for excuses is a whole other matter. Whether they're honest about taking the one-time opportunity to enhance capacity while enhancing safety is another matter. The engineering dept. could always get private orders that "we ain't increasing headways", and "it wouldn't be the worst thing if capacity decreased and we had to get rid of the E" while the public gets strung out on insincere promises. But put in the hands of the engineering dept., I have little doubt it'll be designed exactly to-task.

What "the task" is...that's a good question. Because they can always get orders to kneecap the headways, while the public is told something else.

On the other hand, if they get outed for doing that shit...they don't get to claim poverty for the fix to "un-kneecap" it. The beauty of computers and virtual blocks is that you can reprogram the software to space the trains different instead of waiting 25 years for the money to show up to re-space the signals. That's where the Red Line ATO analogy doesn't fit. It'll cost a lot and require shovels-in-ground to undo the bad decision they made in 1987 with the RL signal blocks around Park/DTX. It wouldn't take any field workers whatsoever to fix that under CBTC, removing a powerful excuse from their arsenal.

 

[Arborway]

Re: Driven By Customer 'Service' Parte Dos

Is the T self(state) insured or do they carry private insurance to cover accidents like this. I think that would play a big role in determining if the $700M is cost effective.

The T is self-insured.

They made a big deal out of it when implementing forward-facing bus cameras in an effort to shut down the tons of crazy lawsuits they get every five minutes.

 

[winstonoboogie]

Re: Driven By Customer 'Service' Parte Dos

A few comments on the Green Line signal discussions:

The review of the potential for a new signal system for the Green Line presented to the MBTA Board was undertaken by the MBTA working with consultants, railway signal engineers
http://www.irse.org/default.aspx
(why do people here keep on calling them “traffic engineers”?) that are well aware of what state-of-the-art moving block CBTC systems are capable of. They made no assumptions about simply replicating the existing fixed-block locations. Why are people here assuming the review was simply assuming existing signal blocks?

But they were also well aware of what the present Green Line signal system is capable of. The present Green Line system is still to this day very impressive in the volume of trains per hour (tph) it can handle. In the peak, the scheduled through-put in the common trunk segment between Copley and Government Center is 48 tph while the actual number can fluctuate even higher when the system is recovering from routine delays such as equipment mechanical problems, or longer than average passenger dwell times. On top of that, there are speed restrictions required because of the tight curves at multiple locations in the original subway between Haymarket and Boylston. The through-put is also impacted by the close spacing of station locations, and the high volume of conflicting movements at the flat junction at Copley.

The existing Green Line signal system achieves this volume through the use of extraordinarily short signal blocks, sometimes only as long as a train length. For a system that was originally installed in phases between 1908 and the 1920s (the subway ran without signals before that) it is impressive that it can handle a greater volume than a modern CBTC system. The significant downside of course is the system is entirely dependent on operators being alert and following the rules. Whether or not that is more of a problem in the last 10-20 years vs.the previous 70-80 years of operation is a topic for another discussion.

The wiki article citation on CBTC has a key paragraph near the end: “When CBTC is applied to systems that previously ran under complete human control with operators working on sight it may actually result in a reduction in capacity (albeit with an increase in safety). This is because CBTC operates with less positional certainty than human sight and also with greater margins for error as worst-case train parameters are applied for the design (e.g. guaranteed emergency brake rate vs. nominal brake rate). “ End of wiki quote

Because of the short block spacing and the lack of automatic stop functions, the present Green Line signal system is a de-facto line of sight system (except at interlockings). Although using Wikipedia as a source for data always has to be taken with caution, the above quote does a pretty good job of quickly explaining why a CBTC installation should not be assumed to allow the same (and certainly not more) trains per hour on the Green Line. It always seems like a cliché to say that the Green Line is unique, but in the world of urban railway operations, it still is. Trolley subways are still fairly unusual in urban railway operations,
http://en.wikipedia.org/wiki/Premetro

and trolley subways running high volumes using tunnel segments dating from before WWII are even more unusual. SEPTA and MUNI are the two closest peers in North America, and both still do not schedule the same number of trains per hour as the present Green Line either before or after their CBTC systems were installed. The 1980 ATO system on MUNI could only handle 23 tph and required a complicated procedure of combining and breaking up trains of different branches at the surface portals. Their CBTC installation allowed them to end that expensive practice and operate separate trains through their subway at 35 tph. But that was a situation fairly unique to their operation, not a lot of lessons for any other operators, and their present system still couldn’t support what the Green Line operates now.

The report to the board did mention the opportunity to mitigate a lower tph number, primarily operating more three car trains (operating longer trains less often, a 3-car every 7 minutes on each branch instead of a 2-car every 5). While such an operation might be able to handle the present cars (not trains) per hour volume, it would not allow for much growth in capacity in the future. Under the present signal system, there is a potential to run 3-car trains at a 48 tph volume if you had enough cars and power system capacity. Under a CBTC system, you could not accommodate that future volume.

The board of course didn’t like the potential price tag anyway and told them to come back with something else.

 

[jass]

Re: Driven By Customer 'Service' Parte Dos

Thanks for the real numbers.

 

[choo]

Re: Driven By Customer 'Service' Parte Dos

A few comments on the Green Line signal discussions:

The review of the potential for a new signal system for the Green Line presented to the MBTA Board was undertaken by the MBTA working with consultants, railway signal engineers
http://www.irse.org/default.aspx
(why do people here keep on calling them “traffic engineers”?) that are well aware of what state-of-the-art moving block CBTC systems are capable of. They made no assumptions about simply replicating the existing fixed-block locations. Why are people here assuming the review was simply assuming existing signal blocks?

But they were also well aware of what the present Green Line signal system is capable of. The present Green Line system is still to this day very impressive in the volume of trains per hour (tph) it can handle. In the peak, the scheduled through-put in the common trunk segment between Copley and Government Center is 48 tph while the actual number can fluctuate even higher when the system is recovering from routine delays such as equipment mechanical problems, or longer than average passenger dwell times. On top of that, there are speed restrictions required because of the tight curves at multiple locations in the original subway between Haymarket and Boylston. The through-put is also impacted by the close spacing of station locations, and the high volume of conflicting movements at the flat junction at Copley.

The existing Green Line signal system achieves this volume through the use of extraordinarily short signal blocks, sometimes only as long as a train length. For a system that was originally installed in phases between 1908 and the 1920s (the subway ran without signals before that) it is impressive that it can handle a greater volume than a modern CBTC system. The significant downside of course is the system is entirely dependent on operators being alert and following the rules. Whether or not that is more of a problem in the last 10-20 years vs.the previous 70-80 years of operation is a topic for another discussion.

The wiki article citation on CBTC has a key paragraph near the end: “When CBTC is applied to systems that previously ran under complete human control with operators working on sight it may actually result in a reduction in capacity (albeit with an increase in safety). This is because CBTC operates with less positional certainty than human sight and also with greater margins for error as worst-case train parameters are applied for the design (e.g. guaranteed emergency brake rate vs. nominal brake rate). “ End of wiki quote

Because of the short block spacing and the lack of automatic stop functions, the present Green Line signal system is a de-facto line of sight system (except at interlockings). Although using Wikipedia as a source for data always has to be taken with caution, the above quote does a pretty good job of quickly explaining why a CBTC installation should not be assumed to allow the same (and certainly not more) trains per hour on the Green Line. It always seems like a cliché to say that the Green Line is unique, but in the world of urban railway operations, it still is. Trolley subways are still fairly unusual in urban railway operations,
http://en.wikipedia.org/wiki/Premetro

and trolley subways running high volumes using tunnel segments dating from before WWII are even more unusual. SEPTA and MUNI are the two closest peers in North America, and both still do not schedule the same number of trains per hour as the present Green Line either before or after their CBTC systems were installed. The 1980 ATO system on MUNI could only handle 23 tph and required a complicated procedure of combining and breaking up trains of different branches at the surface portals. Their CBTC installation allowed them to end that expensive practice and operate separate trains through their subway at 35 tph. But that was a situation fairly unique to their operation, not a lot of lessons for any other operators, and their present system still couldn’t support what the Green Line operates now.

The report to the board did mention the opportunity to mitigate a lower tph number, primarily operating more three car trains (operating longer trains less often, a 3-car every 7 minutes on each branch instead of a 2-car every 5). While such an operation might be able to handle the present cars (not trains) per hour volume, it would not allow for much growth in capacity in the future. Under the present signal system, there is a potential to run 3-car trains at a 48 tph volume if you had enough cars and power system capacity. Under a CBTC system, you could not accommodate that future volume.

The board of course didn’t like the potential price tag anyway and told them to come back with something else.

thanks for the info... great food for thought... what do you think of the riverside line as a way to relieve volume and increase tpm? there seems to be a split decision on that.

 

[omaja]

Re: Driven By Customer 'Service' Parte Dos

A few comments on the Green Line signal discussions:

The review of the potential for a new signal system for the Green Line presented to the MBTA Board was undertaken by the MBTA working with consultants, railway signal engineers
http://www.irse.org/default.aspx
(why do people here keep on calling them “traffic engineers”?) that are well aware of what state-of-the-art moving block CBTC systems are capable of. They made no assumptions about simply replicating the existing fixed-block locations. Why are people here assuming the review was simply assuming existing signal blocks?

Given the degree to which people are assuming the whole Green Line will implode if converted, one would only think that they would be doing something as foolish as overlaying CBTC using the current block layout. Seeing what was actually presented would be some fascinating reading for sure.

But they were also well aware of what the present Green Line signal system is capable of. The present Green Line system is still to this day very impressive in the volume of trains per hour (tph) it can handle. In the peak, the scheduled through-put in the common trunk segment between Copley and Government Center is 48 tph while the actual number can fluctuate even higher when the system is recovering from routine delays such as equipment mechanical problems, or longer than average passenger dwell times. On top of that, there are speed restrictions required because of the tight curves at multiple locations in the original subway between Haymarket and Boylston. The through-put is also impacted by the close spacing of station locations, and the high volume of conflicting movements at the flat junction at Copley.

The existing Green Line signal system achieves this volume through the use of extraordinarily short signal blocks, sometimes only as long as a train length. For a system that was originally installed in phases between 1908 and the 1920s (the subway ran without signals before that) it is impressive that it can handle a greater volume than a modern CBTC system. The significant downside of course is the system is entirely dependent on operators being alert and following the rules. Whether or not that is more of a problem in the last 10-20 years vs.the previous 70-80 years of operation is a topic for another discussion.

Certainly they may schedule upwards of 48 trains per hour, but is that what they're consistently doing? Headways during rush hour are 6-7 minutes on the branches which would give us around 38-40 trains per hour. Even if they are getting 48+ though, there are plenty of wasted trains being shoved through the system at peak hours because of short-turns at Park and horrible bunching (resulting in the first few trains in the bunch being well over capacity while everything coming along immediately behind gets underutilized).

Automation would allow for more regular, reliable scheduling with each branch hitting the intervals they should be along the Government Center-Copley stretch. Given that we'd eliminate a lot of bunching and other shenanigans, I don't think a small decrease in trains per hour (not exactly sure how much of a decrease we'd be talking?) would necessarily equate to worse service and more crowded trains/platforms - you'd just have each train averaging higher passenger loads instead of the current mess they're running.

The wiki article citation on CBTC has a key paragraph near the end: “When CBTC is applied to systems that previously ran under complete human control with operators working on sight it may actually result in a reduction in capacity (albeit with an increase in safety). This is because CBTC operates with less positional certainty than human sight and also with greater margins for error as worst-case train parameters are applied for the design (e.g. guaranteed emergency brake rate vs. nominal brake rate). “ End of wiki quote

Because of the short block spacing and the lack of automatic stop functions, the present Green Line signal system is a de-facto line of sight system (except at interlockings). Although using Wikipedia as a source for data always has to be taken with caution, the above quote does a pretty good job of quickly explaining why a CBTC installation should not be assumed to allow the same (and certainly not more) trains per hour on the Green Line. It always seems like a cliché to say that the Green Line is unique, but in the world of urban railway operations, it still is. Trolley subways are still fairly unusual in urban railway operations,
http://en.wikipedia.org/wiki/Premetro

and trolley subways running high volumes using tunnel segments dating from before WWII are even more unusual. SEPTA and MUNI are the two closest peers in North America, and both still do not schedule the same number of trains per hour as the present Green Line either before or after their CBTC systems were installed. The 1980 ATO system on MUNI could only handle 23 tph and required a complicated procedure of combining and breaking up trains of different branches at the surface portals. Their CBTC installation allowed them to end that expensive practice and operate separate trains through their subway at 35 tph. But that was a situation fairly unique to their operation, not a lot of lessons for any other operators, and their present system still couldn’t support what the Green Line operates now.

The Wikipedia article references a forum post from railroad.net about SEPTA... I don't think anyone would point to them as a shining of example of how to implement CBTC. It's also a bit disingenous to use one horrific implementation to make a generalization about being applied to multiple "systems" as the Wikipedia quote does.

As you note, though, Muni saw an increase in throughput. The two different CBAs in the document I linked to had 30/35 trains an 40/50 trains per hour (off-peak/peak) so I think we can assume that Muni is capable of running upwards of 50 trains per hour, otherwise there'd be no point to providing a CBA for such a scenario. Seems like operating at 36 trains per hour (10 minute headways on its six lines) is more a symptom of lower overall ridership/demand than it is the CBTC system's capabilities.

The report to the board did mention the opportunity to mitigate a lower tph number, primarily operating more three car trains (operating longer trains less often, a 3-car every 7 minutes on each branch instead of a 2-car every 5). While such an operation might be able to handle the present cars (not trains) per hour volume, it would not allow for much growth in capacity in the future. Under the present signal system, there is a potential to run 3-car trains at a 48 tph volume if you had enough cars and power system capacity. Under a CBTC system, you could not accommodate that future volume.

How do you figure? I find it hard to believe it would be possible, given how the T struggles to maintain its current schedule (and I use the term "maintain" loosely) of mostly 2-car trains, for it to support an all 3-car operation, car and power availability notwithstanding, with the same scheduling throughput. Aren't there several blocks that are only long enough for 2-car trains?

 

[Matthew]

Re: Driven By Customer 'Service' Parte Dos

While we're on the topic of switching to more 3-car trains, let me mention this Master's thesis I came across while doing some research:

MBTA Green Line 3-Car Train Operating Plans to Enhance Capacity and Reliability by Alexandra Malikova.

Might be of interest.

 

[winstonoboogie]

Re: Driven By Customer 'Service' Parte Dos

Certainly they may schedule upwards of 48 trains per hour, but is that what they're consistently doing? Headways during rush hour are 6-7 minutes on the branches which would give us around 38-40 trains per hour. Even if they are getting 48+ though, there are plenty of wasted trains being shoved through the system at peak hours because of short-turns at Park and horrible bunching (resulting in the first few trains in the bunch being well over capacity while everything coming along immediately behind gets underutilized).

Since an MIT thesis on Green Line operations was brought up in another message, I will refer to that as well.

Prior to the experiment with operating some three-car trains in Fall 2010, the Green Line peak headways for a portion of both the AM and PM peaks was every 5 minutes on the D and E, slightly shorter than every 5 minutes on the B (a 5/5/4 pattern) and slightly longer than every 5 on the C (5/6/6). If you stood on the platform at Copley outbound from 5 to 5:30 PM and counted the number of trains you saw each fay for that half-hour over a week, the average for the 30-minute observed period would have come out to about 24 trains. Since the scheduling of some three-car trains, there has been some reduction in that amount.

Automation would allow for more regular, reliable scheduling with each branch hitting the intervals they should be along the Government Center-Copley stretch.

Here is a direct quote from the MIT thesis referenced above
“Sources of most of the service unreliability include road traffic, longer than expected dwell times, vehicle malfunctions, and type of driver (slow or fast)”
All of those possible reasons for delay will still be there under an improved signal system. Much of the bunching takes place along the individual branches on the surface and continues into the signalized portion of the subway.

A further issue is the lack of layover space at the Government Center loop. Trains are scheduled to leave Government Center as soon as they arrive, as the loop cannot be blocked (especially since two lines use it). As a consequence, all of the crew recovery time for the B and D lines is located at the outbound end of the route (BC or Riverside). If a train falls behind schedule in the inbound direction, the only way to try and get it on time in the outbound direction is to loop it early at Park St. Giving dispatchers more real-time vehicle location data would make it easier to know when to intervene and make decisions to keep trains on schedule, but there could potentially be cheaper ways to generate this data for dispatchers than only by installing a new signal system.

The Wikipedia article references a forum post from railroad.net about SEPTA... I don't think anyone would point to them as a shining of example of how to implement CBTC.

The main point though is this sentence
“CBTC operates with less positional certainty than human sight and also with greater margins for error as worst-case train parameters are applied for the design (e.g. guaranteed emergency brake rate vs. nominal brake rate)”

There comes a point in a slow speed (because of other constraints), high-frequency operation when a CBTC system would not allow as close a spacing as line of sight. An extreme hypothetical example: CBTC would not have allowed for an operation like this had it existed 115 years ago:

http://www.flickr.com/photos/boston_public_library/5143673992/in/set-72157625136193751/

As you note, though, Muni saw an increase in throughput. The two different CBAs in the document I linked to had 30/35 trains an 40/50 trains per hour (off-peak/peak) so I think we can assume that Muni is capable of running upwards of 50 trains per hour, otherwise there'd be no point to providing a CBA for such a scenario. Seems like operating at 36 trains per hour (10 minute headways on its six lines) is more a symptom of lower overall ridership/demand than it is the CBTC system's capabilities.

Although the MBTA is scheduled (or was scheduled through Fall 2010) for 48 trains per hour during the busiest parts of the peak, the system has to be able to accommodate an even higher number when recovering from a delay. I have heard that in practice vs. theory, MUNI has found it difficult to schedule beyond 35 trains or so per hour on the 5 lines it runs (the K and T operate as a through service, in part because of capacity constaints). Note that MUNI metro is 100% high platform in the signalized tunnel (thus shorter dwell times), has longer station spacing in the subway vs. the Green Line, has higher operating speeds on relatively tangent track, and doesn’t have conflicting moves at flat junctions within the subway. All things that could dilute performance if an identical CBTC system to MUNI’s was installed on the Green Line.

How do you figure? I find it hard to believe it would be possible, given how the T struggles to maintain its current schedule (and I use the term "maintain" loosely) of mostly 2-car trains, for it to support an all 3-car operation, car and power availability notwithstanding, with the same scheduling throughput. Aren't there several blocks that are only long enough for 2-car trains?

I don’t think they have encountered too many problems operating them on the B and the D, but they do have concerns that too many 3-car trains in any one power section could blow a sub-station. That would require upgrades to the electrical system if they were to consistently operate more 3-car trains. The Heath St. loop can only hold a two car train, that would be a problem for operating them all the way on the E line. For the C line, the North Station turn-back would need the interlocking reconfigured so that a 3-car train changing ends would clear the interlocking. I also believe some of the platforms on Beacon St. might have to be extended to hold all of the doors on a three-car train.
A potential future operating scenario, with enough equipment and enough power avialable, would be to operate 3-car trains every five minutes on the B and the D and two-car trains every five on the C and E. I think the computer demand models for GLX service patterns make assumptions about three-car trains on the D Line.

 

[BostonUrbEx]

Re: Driven By Customer 'Service' Parte Dos

Boston to Cape rail service will include Buzzards Bay stop
MBTA passenger rail service will run from Memorial Day weekend to Labor Day


BOURNE COURIER
Posted Dec 10, 2012 @ 05:13 PM


BUZZARDS BAY —

Massachusetts Bay Transportation Authority weekend train service from Boston’s South Station to Hyannis - via a stop in Buzzards Bay - will start May 24 and continue to Labor Day.
Cape Cod Regional Transit Authority Administrator Thomas Cahir said late Monday afternoon the return of passenger rail service to the Cape – after nearly a 25-year absence - will involve five weekend trips and possibly a sixth return trip to Boston on Monday morning.
Cahir told the Bourne Transportation Advisory Committee that Gov. Deval Patrick has approved passenger rail resumption, and a name for the restored service likely would be selected Wednesday.
Cahir said the service needs 635 weekend riders to prove fiscally viable. He said the trains would include two bicycle cars. The overall idea, however, is tap dollars in the Boston market and attract visitors to Cape Cod as well as others to ride the train and thus avoid traffic backups at the canal bridges.
Passenger rail restoration to the Cape has proved to be an on-again/off-again experience over the past several decades. The last service was the Cape Codder in 1989; it was short-lived.
A weekend round-trip ticket will cost $30. The service will be widely marketed, Cahir said, and the Buzzards Bay stop will be coordinated with the Army Corps of Engineers. He said the weekend trains would be coordinated with the dinner trains and regional trash service that rule the rails now.
There will be passenger coordination in Hyannis for riders headed to island ferries and destinations down-Cape.
“This train is exciting,” Cahir said. “But the MBTA is not expanding; it still has deficit concerns. This will be somewhat similar to the Patriots/MBTA train. This is not high-speed commuter rail service. This is five trains a week over the weekends.”
Trains bound for the Cape will depart South Station at 5:10 p.m. on Fridays for stops at Lakeville and Buzzards Bay. The Saturday and Sunday departure times in Boston are set for 8 a.m.
Bourne Administrator Thomas Guerino said the rail service could prove valuable in that it could be marketed in conjunction with the planned 2014 festivities celebrating the Cape Cod Canal centennial observance.
Bourne Police Chief Dennis Woodside said a train could be safely accommodated if the Buzzards Bay stops at Main Street are consigned to three-to-five minute intervals; and not blocking Academy Drive longer than that.
Canal Region Chamber of Commerce Director Marie Oliva said Buzzards Bay parking issues or tangles that evolve near the restored Main Street rail station could easily be resolved.


Cahir said he remains convinced visitors and others would embrace travel to the Cape by train if they can be assured it is reliable, dependable and clean; and especially if their need to get around without a vehicle once they reach Hyannis is accommodated.
“This is another option for those who want to come down to the Cape,” he said. “To spend their money without their cars; no congestions at the bridges. And it should bring some economic benefits to the community.”
There will be no MBTA cherry-sheet assessment charged to Bourne for the Buzzards Bay stop, Cahir said.



Read more: Boston to Cape rail service will include Buzzards Bay stop - - The Bourne Courier http://www.wickedlocal.com/bourne/n...-will-include-Buzzards-Bay-stop#ixzz2EhAfaIVp

 

[JohnAKeith]

Re: Driven By Customer 'Service' Parte Dos

I went to get a new Charlie Card yesterday. The attendant misunderstood that all I needed was a new card, not to transfer my existing card's balance to a new card, and gave me a number to wait for a customer service agent. Therefore, I was able to enjoy myself while watching the assembled group of misfits surrounding me.

If you've missed having the Greyhound / Trailways bus station in Boston, you'll be overjoyed at the scene in the MBTA office.

 

[Ron Newman]

Re: Driven By Customer 'Service' Parte Dos

I was in and out of there in about 45 seconds when I had a ticket whose value I wanted to transfer to my card.

 

[Matthew]

Re: Driven By Customer 'Service' Parte Dos

You can get a new card at just about any convenience store or Star Market.