Uncivil_Engineer
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I really hope they're taking the 225' platform length requirement into account as part of the BU Bridge-Packard's Corner stop consolidation.
General MBTA Topics (Multi Modal, Budget, MassDOT)
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I really hope they're taking the 225' platform length requirement into account as part of the BU Bridge-Packard's Corner stop consolidation.
They are. I believe they are designed with the possibility of 3 car trains in mind, and I assume the amount of things that have been future proofed for 3 car trains is why they went with 112' cars. Longer could replace the current fleet more easily and give a small capacity increase, but would make any further capacity increase near impossible.
I'll add that Warren St/Allston St/Griggs St are in the area of Comm Ave Phase 3/4. If the MBTA and Boston continue to coordinate in regards to these phases, there like will be consolidation and improvements there. Eliminate Allston St and you have taken care of 2 platforms on the list. Eliminate or renovate Griggs to get rid of 2 more. BC should be fixed as part of the work on the yard, then you only have 4 platforms at 2 stations (Sutherland, Blandford) left with issues.
Joel N. Weber II
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A three 116' car train would be 348' long. I think at least some of the platforms can accommodate that.
Joel N. Weber II
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http://www.archboston.org/community/showthread.php?p=310020#post310020 notes that the Blue Book reports B having roughly similar ridership to D, and C and E each having roughly half the ridership of B or D.
If the goal is to run the same headways on each branch and have capacity for the current ridership, it might make sense to be thinking about running 2 x 116' trains on B and D and 1 x 116' trains on C and E.
However, it looks like they're making decisions based on construction difficulty: apparently Heath St is the only E branch station that can't handle 225' trains (although I really want to see Mission Park and Riverway rebuilt to provide accessible platforms that don't dump passengers into a travel lane, and Fenwood Road and Back of the Hill eliminated), the D branch only has three stations that need lengthening, and B and C have lots of platforms that need lengthening.
From an ADA perspective, I do not think they should be waiting 12 years to fix the B and C platforms. Any platform that's not fully accessible for low floor cars should start getting rebuilt to some approximation of the future standards as soon as practical; perhaps on the C branch that's going to mean waiting for all door boarding infrastructure, but if they're not working on this on the B branch now it shows an antipathy toward wheelchair users. (My understanding is that they think the Type 7 cars interfere with platforms built for Type 8 level boarding, so if the platforms are improved while the Type 7s are still around, they'll have to be built too low for level boarding, and then raised when the Type 7s go away.)
I didn't see that in the slides, but it seems like building a Green Line yard at Needham Junction along with converting the Needham stations from commuter rail to Green Line is the obvious solution.
They could keep running them on the less crowded branches, or ship them to Mattapan or Lowell, or use them for a Riverside to Kenmore train that turns around on the Kenmore loop if Needham takes Riverside's slots to Park St.
Joel N. Weber II
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Re: Park St loop
I've been assuming that as long as there's no Pleasant St Incline service, the number of trains per hour that a platform at Boylston can handle should be the same as the number of trains per hour that a platform at Government Center can handle, and if you have adequate facilities for turning trains around north of Park St, there's no reason to turn trains around at Park St.
During the Lechmere shutdown for Green Line Extension construction the only options for turning trains around will be Park, Government Center, and North Station, and turning one branch around at Park will make lots of sense to try to minimize the problems associated with that shutdown.
If Dudley service happens and C or E needs to turn on the existing Park St loop, it might be possible to permanently assign the Type 9s to the C branch if the 9s can go through the Park St loop and the 10s can't, and if the C branch ends up turning at Park St to free up capacity at Government Center for Dudley trains. But Google Maps seems to think Park to Cleveland Circle is a 37 minute trip one way, so for 6 minute headways you need at least 13 trainsets for probably not enough recovery time and no spares; if the goal is to run 2 car Type 9 trains on the C branch, then 24 Type 9 cars wouldn't be enough. The E branch is only 28 minutes each way, which means 10 trainsets might be able to cover it with minimal recovery time, but then you might be committing to not extend the trains to Hyde Sq. Or maybe some of the Type 8s could be kept for a very long time, but it sounds like most people think that isn't really a good approach.
I suspect that the best way to make 116' cars work with Dudley service might be to have the C or E branch change ends on the northbound fence track at Park St, at which point that crossover the FMCB is looking at spending millions on to allow trains on that track to proceed to Government Center probably becomes worthless.
I've been assuming that as long as there's no Pleasant St Incline service, the number of trains per hour that a platform at Boylston can handle should be the same as the number of trains per hour that a platform at Government Center can handle, and if you have adequate facilities for turning trains around north of Park St, there's no reason to turn trains around at Park St.
During the Lechmere shutdown for Green Line Extension construction the only options for turning trains around will be Park, Government Center, and North Station, and turning one branch around at Park will make lots of sense to try to minimize the problems associated with that shutdown.
If Dudley service happens and C or E needs to turn on the existing Park St loop, it might be possible to permanently assign the Type 9s to the C branch if the 9s can go through the Park St loop and the 10s can't, and if the C branch ends up turning at Park St to free up capacity at Government Center for Dudley trains. But Google Maps seems to think Park to Cleveland Circle is a 37 minute trip one way, so for 6 minute headways you need at least 13 trainsets for probably not enough recovery time and no spares; if the goal is to run 2 car Type 9 trains on the C branch, then 24 Type 9 cars wouldn't be enough. The E branch is only 28 minutes each way, which means 10 trainsets might be able to cover it with minimal recovery time, but then you might be committing to not extend the trains to Hyde Sq. Or maybe some of the Type 8s could be kept for a very long time, but it sounds like most people think that isn't really a good approach.
I suspect that the best way to make 116' cars work with Dudley service might be to have the C or E branch change ends on the northbound fence track at Park St, at which point that crossover the FMCB is looking at spending millions on to allow trains on that track to proceed to Government Center probably becomes worthless.
I'm beginning to think there's no real excuse for giving E priority over B. B has the larger issues with capacity. And if we're really just looking at Sutherland & Blandford vs Heath St, I would argue that Sutherland & Blandford would be easier to lengthen the platforms since Heath St will likely require a complete redesign and seizing land from the VA hospital parking lot.
millerm277
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Some opinions regarding the current discussion:
- Warren/Allston/Griggs may be close together, but that stretch is fairly high ridership. If you close two of those, you're going to make Warren and Harvard two of the busiest surface stops in the system.
- In the current (pre-AFC 2.0) world, that likely doesn't make for many benefits, as you'll have a very long line of people waiting to pay/tap in. Post AFC 2.0, that may be different.
- Warren/Allston/Griggs may be close together, but that stretch is fairly high ridership. If you close two of those, you're going to make Warren and Harvard two of the busiest surface stops in the system.
- In the current (pre-AFC 2.0) world, that likely doesn't make for many benefits, as you'll have a very long line of people waiting to pay/tap in. Post AFC 2.0, that may be different.
Joel N. Weber II
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Re: Green Line door configuration and platform lengthening
I think if the T decided today that they wanted to get B, D, and E rebuilt for 225' platforms by December 2022, and tomorrow the legislature gave them money to get it done, it wouldn't be at all difficult.
The Heath St VA land question is an interesting one. Before I'd seen their presentation this week, I'd been assuming that longer Green Line trains were going to require the T to get some of the VA's land. Page 84 of https://cdn.mbta.com/sites/default/...018-05-07-fmcb-green-line-future-capacity.pdf shows a proposed straight line parallel to a part of South Huntington that stays just to the north of the existing track loop (and I guess the parking lot it goes through is probably a T parking lot?). But when I try to pick roughly the endpoints shown in T's illustration using the Google Maps Measure Distance tool, it seems to be roughly 170' long, which would be enough for 1 x 116' but not 2 x 116'.
Given the concerns with the tight curve at the existing Heath St loop, having a way to run 1 car 116' trains that eliminates the loop without having potentially difficult land acquisition issues is potentially worth something, but I also hope they will work with the VA to explore whether a longer platform with some sort of land swap deal would make more sense. (And there might be value in trying to locate the station closer to the VA's front door, but on the other hand doing that would make the station less convenient for residents of Heath St.)
I'm not sure why 225' is being treated as the magic number for platform length. 2 x 116' is 232', so if 225' is the magic number, then 7' of the length of a 2 x 116' train will be past the end of the platform. Given that the doors aren't expected to be at the end of the Type 10 cars, that's probably fine, but depending on the exact placement of the doors, it might turn out that there might be more than 3.5' from each end of the train to the edge of the first door. And even with the Type 7/8 trains, when using a platform on the right side of the train there's no door at the back of the train meeting the platform so somewhat less than 225' ought to work for a three car train.
If the doors end up 7' from the end of each car, 232' - 2 x 7' works out to 218', at which point roughly half of the supposedly too short platforms on page 19 of the capacity PDF might suddenly become acceptable if we're just looking at length and ignoring any potential ADA issues. If the doors can be kept at least 9' away from the ends of the train cars, the entire D branch becomes acceptable as is. If the doors end up at least 11' away from the ends of the train cars, then perhaps Boylston eastbound would not need any reconstruction. If the doors end up at least 12.5' from the end of the train, it looks like for 2 x 116' trains, the only stations needing construction would be Heath St, Boston College, eastbound Blandford St, and a bunch of C branch stations.
If we end up with 12.5' of non-door space at the end of a train, then 5.333' of first doorway (which I believe is the width of the new Red and Orange Line doorways), then 16' of not doorway, 5.333' of second doorway, then 16' of not doorway, 5.333' of third doorway, then 16' of not doorway, 5.333' of fourth doorway, then 16' of not doorway, 5.333' of fifth doorway, then 12.5' of non-door space at the far end of the train, I believe that adds up to 115.666'. Perhaps that means that 12' 8" from the end of the car to the first doorway might be desirable. And if the cab is 4' - 5' long, that arrangement would nicely center the doors on the passenger areas while limiting the need to lengthen existing platforms. (Although it also looks like the different section sizes may lead to the doors not being that evenly spaced.)
They do seem to have assumed that the doors would go directly adjacent to the cab, but it's not clear if there's any reason for that other than habit from when the motorperson has been expected to monitor fare payment.
The existing Boston College station apparently isn't even long enough for 150' two car trains, at 138' westbound (where it discharges passengers) and 130' eastbound (where maybe it does front door boarding only?). Does it turn out to be long enough for the doors that are in use to line up next to the platforms?
Page 10 of the PDF shows a photograph of the Clinton St underpass that seems to have a railing that suggests it has a staircase. Could / should they rebuild that as a wheelchair ramp while rebuilding the bridge?
I think if the T decided today that they wanted to get B, D, and E rebuilt for 225' platforms by December 2022, and tomorrow the legislature gave them money to get it done, it wouldn't be at all difficult.
The Heath St VA land question is an interesting one. Before I'd seen their presentation this week, I'd been assuming that longer Green Line trains were going to require the T to get some of the VA's land. Page 84 of https://cdn.mbta.com/sites/default/...018-05-07-fmcb-green-line-future-capacity.pdf shows a proposed straight line parallel to a part of South Huntington that stays just to the north of the existing track loop (and I guess the parking lot it goes through is probably a T parking lot?). But when I try to pick roughly the endpoints shown in T's illustration using the Google Maps Measure Distance tool, it seems to be roughly 170' long, which would be enough for 1 x 116' but not 2 x 116'.
Given the concerns with the tight curve at the existing Heath St loop, having a way to run 1 car 116' trains that eliminates the loop without having potentially difficult land acquisition issues is potentially worth something, but I also hope they will work with the VA to explore whether a longer platform with some sort of land swap deal would make more sense. (And there might be value in trying to locate the station closer to the VA's front door, but on the other hand doing that would make the station less convenient for residents of Heath St.)
I'm not sure why 225' is being treated as the magic number for platform length. 2 x 116' is 232', so if 225' is the magic number, then 7' of the length of a 2 x 116' train will be past the end of the platform. Given that the doors aren't expected to be at the end of the Type 10 cars, that's probably fine, but depending on the exact placement of the doors, it might turn out that there might be more than 3.5' from each end of the train to the edge of the first door. And even with the Type 7/8 trains, when using a platform on the right side of the train there's no door at the back of the train meeting the platform so somewhat less than 225' ought to work for a three car train.
If the doors end up 7' from the end of each car, 232' - 2 x 7' works out to 218', at which point roughly half of the supposedly too short platforms on page 19 of the capacity PDF might suddenly become acceptable if we're just looking at length and ignoring any potential ADA issues. If the doors can be kept at least 9' away from the ends of the train cars, the entire D branch becomes acceptable as is. If the doors end up at least 11' away from the ends of the train cars, then perhaps Boylston eastbound would not need any reconstruction. If the doors end up at least 12.5' from the end of the train, it looks like for 2 x 116' trains, the only stations needing construction would be Heath St, Boston College, eastbound Blandford St, and a bunch of C branch stations.
If we end up with 12.5' of non-door space at the end of a train, then 5.333' of first doorway (which I believe is the width of the new Red and Orange Line doorways), then 16' of not doorway, 5.333' of second doorway, then 16' of not doorway, 5.333' of third doorway, then 16' of not doorway, 5.333' of fourth doorway, then 16' of not doorway, 5.333' of fifth doorway, then 12.5' of non-door space at the far end of the train, I believe that adds up to 115.666'. Perhaps that means that 12' 8" from the end of the car to the first doorway might be desirable. And if the cab is 4' - 5' long, that arrangement would nicely center the doors on the passenger areas while limiting the need to lengthen existing platforms. (Although it also looks like the different section sizes may lead to the doors not being that evenly spaced.)
They do seem to have assumed that the doors would go directly adjacent to the cab, but it's not clear if there's any reason for that other than habit from when the motorperson has been expected to monitor fare payment.
The existing Boston College station apparently isn't even long enough for 150' two car trains, at 138' westbound (where it discharges passengers) and 130' eastbound (where maybe it does front door boarding only?). Does it turn out to be long enough for the doors that are in use to line up next to the platforms?
Page 10 of the PDF shows a photograph of the Clinton St underpass that seems to have a railing that suggests it has a staircase. Could / should they rebuild that as a wheelchair ramp while rebuilding the bridge?
Re: Green Line door configuration and platform lengthening
I think that line is just the Google Transit view, not a proposal. I was surprised that unlike all the other ones they mention with some detail in the presentation (Riverside showing proposed track locations, etc.), Heath St is just an aerial screenshot. I wonder if they are purposefully not showing options to not get abutters upset about a "plan" that doesn't actually exist yet. It would also be interesting to see if extending the E to Hyde Square and using Barbara St as a stub end station would be easier (less costly or more beneficial) than a land swap with the VA, especially considering how well the state is faring with another federal agency for a land swap (USPS at SS).
I think that line is just the Google Transit view, not a proposal. I was surprised that unlike all the other ones they mention with some detail in the presentation (Riverside showing proposed track locations, etc.), Heath St is just an aerial screenshot. I wonder if they are purposefully not showing options to not get abutters upset about a "plan" that doesn't actually exist yet. It would also be interesting to see if extending the E to Hyde Square and using Barbara St as a stub end station would be easier (less costly or more beneficial) than a land swap with the VA, especially considering how well the state is faring with another federal agency for a land swap (USPS at SS).
Joel N. Weber II
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Re: Heath St / Hyde Sq
Now that you've pointed that out, I can see that the Google Maps satellite view with the Transit option turned on shows pretty much that line, which would explain where that line comes from and why it wouldn't make much sense for them to be talking about 225' platforms and then proposing something shorter.
Misinterpreting that line did still cause me realize that there's another possible alignment that might be worth considering, but it also seems to be the case that the MBTA's very recent presentation isn't listing Heath St as one of the tighter curves, even though EGE's MIT thesis did mention the Heath St curve as somewhat tight IIRC.
If it were possible to build a new east side of S Huntington sidewalk on top of the grass in front of the VA Medical Center, it might be possible to use the existing sidewalk space for a northbound track, the parking lane for an island platform, and the bike lane and a bit of a travel lane for the southbound track, and given that the street view images suggest that that part of the street is sort of in a low point, maybe a roof over the station could provide a bicycle path. Perhaps the north end of such a platform could be just to the south of the existing loop, and the loop could then turn into a pedestrian walkway to Heath St.
Barbara St is narrow enough that I suspect trying to get part of the parking lot just to the north of Perkins St would be a better choice in terms of not disrupting what's there. Also, in the narrow section of Centre St that seems to be used as the excuse for not continuing the E branch past Hyde Sq, most of the buildings are one story retail; if they could be rebuilt as 10 story mixed use retaining first floor retail, and moved back 20' to 40' from the street in the process, we might be able to widen the street enough to extend the trains further south someday.
But a Hyde Sq extension doesn't eliminate the need to have a modern platform somewhere near VA / Heath St, and if it's done right the new platform can be designed to work initially as a terminus but then continue to function if the E branch is later extended south.
Now that you've pointed that out, I can see that the Google Maps satellite view with the Transit option turned on shows pretty much that line, which would explain where that line comes from and why it wouldn't make much sense for them to be talking about 225' platforms and then proposing something shorter.
Misinterpreting that line did still cause me realize that there's another possible alignment that might be worth considering, but it also seems to be the case that the MBTA's very recent presentation isn't listing Heath St as one of the tighter curves, even though EGE's MIT thesis did mention the Heath St curve as somewhat tight IIRC.
If it were possible to build a new east side of S Huntington sidewalk on top of the grass in front of the VA Medical Center, it might be possible to use the existing sidewalk space for a northbound track, the parking lane for an island platform, and the bike lane and a bit of a travel lane for the southbound track, and given that the street view images suggest that that part of the street is sort of in a low point, maybe a roof over the station could provide a bicycle path. Perhaps the north end of such a platform could be just to the south of the existing loop, and the loop could then turn into a pedestrian walkway to Heath St.
Barbara St is narrow enough that I suspect trying to get part of the parking lot just to the north of Perkins St would be a better choice in terms of not disrupting what's there. Also, in the narrow section of Centre St that seems to be used as the excuse for not continuing the E branch past Hyde Sq, most of the buildings are one story retail; if they could be rebuilt as 10 story mixed use retaining first floor retail, and moved back 20' to 40' from the street in the process, we might be able to widen the street enough to extend the trains further south someday.
But a Hyde Sq extension doesn't eliminate the need to have a modern platform somewhere near VA / Heath St, and if it's done right the new platform can be designed to work initially as a terminus but then continue to function if the E branch is later extended south.
Joel N. Weber II
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Re: Green Line Type 10 door width
Page 35 of the capacity PDF has detailed dimensions of the proposed cars.
The second and sixth segment are each 4326 mm long, which is a bit more than 14'; I don't see any clear obvious reason why they couldn't have 64" doorways if that would match what the Red and Orange lines are going to end up with, although ~3' for the door to slide into plus ~5.5' for the doorway plus ~5.5' for the other door to slide into plus non-door space may be tight if that ~5.5' of non-opening space needs to accommodate both a 4' long wheelchair area and an articulation joint. (Having the floor painted with a wheelchair area that blocks the door might work, except that I suspect there would be some passengers who will feel entitled to harass wheelchair users for blocking the door in that case, unless of course the door is just permanently made narrower so that the wheelchair users aren't superficially appearing to be blocking the doors.)
If we assume that the section lengths and wheel sizes and locations have been carefully chosen and need to be what is proposed and then try to fit doors into whatever space is left, the third and fifth section probably really can't have doors: the 7th result at https://www.google.com/search?q=lrv+wheel+diameter says 610mm / 24" to 710mm / 28" wheel diameter is likely, and page 35 of the capacity PDF says the two axles in each truck will be 1900mm apart, which is about 6.23'; a doorway between the wheels would therefore have to be a bit less than 2' wide, which is probably not worth having at all, and the 2824 mm long third and fifth sections with the trucks are 9.26' long, which means they have about 1.5' from the axle center to the end of the section, which is barely more than the wheel radius.
The proposed center section is 2802 mm which is 9.19'. If you want the doors to be one leaf sliding in each direction, there isn't space for a 64" doorway to have doors that slide all the way open. However, some elevators have doors with two leaves that go at different speeds in the same direction, and if that sort of design could be reliably implemented in an LRV, with a total of four leaves that are 16" each, such that we'd only need 16" on one side and 16" on the other side for the door to disappear into when opened, that would only require 96" or 8', which conveniently is less than 9.19'.
In the first and last segment, it looks like 64" doorways would be tricky; the wheels are in the way on the part near the center of the train. I think there's a chance it might be possible to have a 32" leaf that slides toward the center of the train that is parallel to the sides of the train at the truck in that segment, and extend the tapered segment at the front to the point where the two 32" leaves would meet, such that the two leaves would not be parallel to each other, and the leaf towards the end of the car would slide through the tapered section to open. Making that work would would involve narrowing the cab a bit, and reallocating about 1' of the train's length that is being proposed for the operator cab to the passenger area (and I don't know whether that would lead to too little space for the operator, but anticlimber to back of cab seems to be 7' as currently proposed which seems quite generous), and while the door / wall / roof would be tapered at that closest-to-the-end leaf, the train would need to have a non-tapered exterior floor next to that leaf to meet the platform.
Page 35 of the capacity PDF has detailed dimensions of the proposed cars.
The second and sixth segment are each 4326 mm long, which is a bit more than 14'; I don't see any clear obvious reason why they couldn't have 64" doorways if that would match what the Red and Orange lines are going to end up with, although ~3' for the door to slide into plus ~5.5' for the doorway plus ~5.5' for the other door to slide into plus non-door space may be tight if that ~5.5' of non-opening space needs to accommodate both a 4' long wheelchair area and an articulation joint. (Having the floor painted with a wheelchair area that blocks the door might work, except that I suspect there would be some passengers who will feel entitled to harass wheelchair users for blocking the door in that case, unless of course the door is just permanently made narrower so that the wheelchair users aren't superficially appearing to be blocking the doors.)
If we assume that the section lengths and wheel sizes and locations have been carefully chosen and need to be what is proposed and then try to fit doors into whatever space is left, the third and fifth section probably really can't have doors: the 7th result at https://www.google.com/search?q=lrv+wheel+diameter says 610mm / 24" to 710mm / 28" wheel diameter is likely, and page 35 of the capacity PDF says the two axles in each truck will be 1900mm apart, which is about 6.23'; a doorway between the wheels would therefore have to be a bit less than 2' wide, which is probably not worth having at all, and the 2824 mm long third and fifth sections with the trucks are 9.26' long, which means they have about 1.5' from the axle center to the end of the section, which is barely more than the wheel radius.
The proposed center section is 2802 mm which is 9.19'. If you want the doors to be one leaf sliding in each direction, there isn't space for a 64" doorway to have doors that slide all the way open. However, some elevators have doors with two leaves that go at different speeds in the same direction, and if that sort of design could be reliably implemented in an LRV, with a total of four leaves that are 16" each, such that we'd only need 16" on one side and 16" on the other side for the door to disappear into when opened, that would only require 96" or 8', which conveniently is less than 9.19'.
In the first and last segment, it looks like 64" doorways would be tricky; the wheels are in the way on the part near the center of the train. I think there's a chance it might be possible to have a 32" leaf that slides toward the center of the train that is parallel to the sides of the train at the truck in that segment, and extend the tapered segment at the front to the point where the two 32" leaves would meet, such that the two leaves would not be parallel to each other, and the leaf towards the end of the car would slide through the tapered section to open. Making that work would would involve narrowing the cab a bit, and reallocating about 1' of the train's length that is being proposed for the operator cab to the passenger area (and I don't know whether that would lead to too little space for the operator, but anticlimber to back of cab seems to be 7' as currently proposed which seems quite generous), and while the door / wall / roof would be tapered at that closest-to-the-end leaf, the train would need to have a non-tapered exterior floor next to that leaf to meet the platform.
Joel N. Weber II
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Re: Green Line proposed platform length
I think the MBTA's proposed design actually requires a 209.8' platform if the operator can consistently line up the front of the front door with the front of the platform and the ends of the train that don't have doors are allowed to go beyond the end of the platform if I did the math right.
Specifically, 34656mm * 2 gives 69312mm from coupler face to coupler face for two cars.
Subtracting 34046mm anticlimber to anticlimber of one car from 34656mm coupler to coupler of one car gives 610mm
End door center is listed as 2833mm, and subtracting half of the 914mm doorway width from that gives 2376mm anticlimber to edge of door.
Taking the 69312mm from coupler to coupler of the pair of cars and subtracting the 610mm to convert that to the anticlimber to anticlimber distance and then subtracting the 2376mm twice gives 63950mm, which is 209.8'.
That suggests it might fit everywhere in the central subway and everywhere on the D branch; the Heath St platform length is still an issue, though, as is Boston College, Blandford, and (by about 3') Sutherland westbound, plus some C branch stations.
And if the door leaf in the tapered section approach turns out to be usable, and if you ignore the trigonometry of the tapered 32" leaf not actually taking up quite a full 32" of the car length, 4773 - (1900 / 2) - (710 / 2) is 3468mm from the anticlimber to the nearest edge of the nearest wheel if you assume a 710mm diameter wheel, and then subtracting 1626mm of doorway yields 1842mm from anticlimber to doorway, which requires roughly a 65018mm aka 213.3' platform (and that .3 probably overestimates the precision because I skipped the trig along with the space that would be taken up by the wheel cover if it's a relatively large wheel). It looks like Boylston eastbound and St Mary's in both directions are the platforms that would have to be lengthened for the 64" doors at ends approach but not for the car dimensions the T has proposed.
I think the MBTA's proposed design actually requires a 209.8' platform if the operator can consistently line up the front of the front door with the front of the platform and the ends of the train that don't have doors are allowed to go beyond the end of the platform if I did the math right.
Specifically, 34656mm * 2 gives 69312mm from coupler face to coupler face for two cars.
Subtracting 34046mm anticlimber to anticlimber of one car from 34656mm coupler to coupler of one car gives 610mm
End door center is listed as 2833mm, and subtracting half of the 914mm doorway width from that gives 2376mm anticlimber to edge of door.
Taking the 69312mm from coupler to coupler of the pair of cars and subtracting the 610mm to convert that to the anticlimber to anticlimber distance and then subtracting the 2376mm twice gives 63950mm, which is 209.8'.
That suggests it might fit everywhere in the central subway and everywhere on the D branch; the Heath St platform length is still an issue, though, as is Boston College, Blandford, and (by about 3') Sutherland westbound, plus some C branch stations.
And if the door leaf in the tapered section approach turns out to be usable, and if you ignore the trigonometry of the tapered 32" leaf not actually taking up quite a full 32" of the car length, 4773 - (1900 / 2) - (710 / 2) is 3468mm from the anticlimber to the nearest edge of the nearest wheel if you assume a 710mm diameter wheel, and then subtracting 1626mm of doorway yields 1842mm from anticlimber to doorway, which requires roughly a 65018mm aka 213.3' platform (and that .3 probably overestimates the precision because I skipped the trig along with the space that would be taken up by the wheel cover if it's a relatively large wheel). It looks like Boylston eastbound and St Mary's in both directions are the platforms that would have to be lengthened for the 64" doors at ends approach but not for the car dimensions the T has proposed.
Re: Green Line proposed platform length
Why are we designing trains of the future with operators?
Why are we designing trains of the future with operators?
TallIsGood
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Equilibria
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Re: Green Line proposed platform length
I doubt you can legally operate an automated train at a reasonable speed where people can run across the tracks.
I doubt you can legally operate an automated train at a reasonable speed where people can run across the tracks.
Re: Green Line proposed platform length
Cool we can have Waymo operating autonomous taxis all over Phoenix with no regulation but heavens forbid a train on a track get automated in 2021
Not like the tech hasnt existed for over 50 years
Cool we can have Waymo operating autonomous taxis all over Phoenix with no regulation but heavens forbid a train on a track get automated in 2021
Not like the tech hasnt existed for over 50 years
DominusNovus
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millerm277
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Re: Green Line proposed platform length
I don't believe anywhere in the world is running automated trains/trams on lines that aren't grade separated.
I don't believe anywhere in the world is running automated trains/trams on lines that aren't grade separated.
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This discussion about turning radii, vehicles, stations, yards, etc is important and will get lost in this general MBTA thread. Can someone please move all the green line vehicle & modernization discussion to the Type 10 thread so it is properly archived for reference?
Thanks.
Thanks.