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Old 05-16-2018, 07:13 AM   #121
Arlington
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Re: TransitMatters Regional Rail Plan

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We actually aren't recommending bilevels. Bilevels increase dwell time dramatically. We are currently working on explaining how we can have enough capacity with flats only in a capacity appendix.
flats offer more and wider doors? (and, once moving faster, doing more turns per shift can offer same capacity) is that it?
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Old 05-16-2018, 08:52 AM   #122
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Re: TransitMatters Regional Rail Plan

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flats offer more and wider doors? (and, once moving faster, doing more turns per shift can offer same capacity) is that it?
For dwell time, yes. For general capacity, we believe we can run trains frequently enough to boost capacity on the lines even with eliminating bilevels.
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Old 05-16-2018, 09:43 AM   #123
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Re: TransitMatters Regional Rail Plan

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We actually aren't recommending bilevels. Bilevels increase dwell time dramatically. We are currently working on explaining how we can have enough capacity with flats only in a capacity appendix.
I think it depends. The current MBTA bi-levels arent great because they have poor circulation.

The ones RER uses in Paris are much better. Doors are twice as wide, and there are twice the staircases.
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Old 05-16-2018, 09:55 AM   #124
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Re: TransitMatters Regional Rail Plan

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I think it depends. The current MBTA bi-levels arent great because they have poor circulation.

The ones RER uses in Paris are much better. Doors are twice as wide, and there are twice the staircases.
Paris RER dwell times are actually far above ideal standards.
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Old 05-20-2018, 12:26 PM   #125
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Re: TransitMatters Regional Rail Plan

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Problem with putting the batteries in the trucks is that a battery pack that can power a commuter rail coach any reasonable distance is going to be kind of big, and powered trucks don't have a whole lot of extra space.
At https://teslamotorsclub.com/tmc/thre...teries.115796/ I explore this in detail; 6' long x 4' wide x 30" tall inside the wheels, plus 6' long x 1' wide x 30" tall on the outside on each side for each train axle would have about the same total volume as 4 Tesla Model S battery packs capable of storing 4 x 100kWh = 400kWh, and I think with a compact suspension design a railroad truck probably could be made with space for that.

Also, while for some reason my memory was convinced I'd seen 3 MPH/s as the rate of acceleration for some Metro North cars, the best reference I could find today was http://www.railroad.net/forums/viewt...?f=16&t=158567 which claims 2 MPH/s. Does anyone have other data that might help to confirm how well the best North American commuter trains currently accelerate? Can TransitMatters cite a source for the rate of acceleration of their preferred overhead power option? (If 2 MPH/s turns out to be the best Metro North can do, it looks quite possible that a fully loaded Tesla Semi might be able to accelerate faster than a Metro North EMU train using overhead power.)
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Old 05-20-2018, 01:24 PM   #126
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Re: TransitMatters Regional Rail Plan

You're still forgetting the space taken up by the motors, which aren't small. If you've ever looked at a powered truck without a railcar on it, there is no space left.
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Old 05-20-2018, 06:51 PM   #127
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Re: TransitMatters Regional Rail Plan

That 400kWh of battery pack takes up about 90 cubic feet (when estimating based on Model S pack size; using the larger model 3 cells and changing the overall shape might reduce the size). http://www.evwest.com/catalog/produc...roducts_id=476 lists one Tesla Model S motor at about 5.9 cubic feet, so 4 Tesla motors might be somewhere around 23.6 cubic feet. (It would be ideal to find Model 3 numbers instead of Model S numbers, but those numbers seem to be harder to come by.) Also, that photograph suggests that the motor is not exactly rectangular, so maybe if it fits inside a rectangular box roughly 5.9 cubic feet its actual volume might be even smaller.

Also, you might not need the full 90 cubic feet / 400 kWh of batteries per axle; the comment on Alon Levy's blog post claimed 1.1 megawatt hour is needed for a Providence to Boston trip for a 320 ton train, and if that train consists of four 80 ton cars, each of the 16 axles on the train only needs about 69 kWh of batteries connected. There's also the question of whether you get adequate acceleration, but it looks like the 300 mile range Tesla Semi may accelerate just as well as the 500 mile range version, and if 2 MPH/s is good enough for Metro North it might be good enough for a minimal battery powered train too; if the 800kWh estimate for the 500 mile range Tesla Semi turns out to be accurate, then 160kWh per axle might provide enough batteries to achieve 2 MPH/s. (And that assumes each Kawasaki bilevel car with batteries added would weigh 160,000 pounds; since they'd actually weigh a bit less, the battery packs could probably be downsized a bit further. Also, if the goal is reduced to 2 MPH/s, downsizing to three Tesla Model 3 motors per truck instead of four ought to work, and perhaps some trucks could even get only two Tesla Model 3 motors.)

If you look at the gasoline engine in a 1960s Chevy sedan, can you conclude that a smaller gasoline engine could not possibly work in a 2018 Toyota Camry?
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Old 05-20-2018, 08:49 PM   #128
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Re: TransitMatters Regional Rail Plan

Joel: can you please use the thread starter to start a battery-electric Transit thread and stop posting on TransitMatters' thread?

It is trivially true that anything that TM proposes will be to the exclusion of other tech and modes--but, just as it would not be fair to beat a dog for being the wrong sort of cat, it is wrong to beat up on a fast, cheap, off-the-shelf kit of cat(enary) parts for not being pioneering tech.

I could hijack this thread to sing the virtues of e-bikes as the solution for Zone 1A, AVs, or e-navettes, or whatnot but none would give the TM team the respect they've earned of taking their proposal seriously on it's own terms--a proposal that MA and RI politicians can focus on for immediate planning and procurement cycles.
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Old 05-21-2018, 08:36 AM   #129
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Re: TransitMatters Regional Rail Plan

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Joel: can you please use the thread starter to start a battery-electric Transit thread and stop posting on TransitMatters' thread?

It is trivially true that anything that TM proposes will be to the exclusion of other tech and modes--but, just as it would not be fair to beat a dog for being the wrong sort of cat, it is wrong to beat up on a fast, cheap, off-the-shelf kit of cat(enary) parts for not being pioneering tech.

I could hijack this thread to sing the virtues of e-bikes as the solution for Zone 1A, AVs, or e-navettes, or whatnot but none would give the TM team the respect they've earned of taking their proposal seriously on it's own terms--a proposal that MA and RI politicians can focus on for immediate planning and procurement cycles.
Yes please! If this forum had an ‘agree’ button, I’d use it right now. Hell, even if we just kept hijacking this thread for NSRL, it would still be hijacking, and that is something that is on their agenda.
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Old 05-21-2018, 12:30 PM   #130
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Re: TransitMatters Regional Rail Plan

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Originally Posted by Arlington View Post
Joel: can you please use the thread starter to start a battery-electric Transit thread and stop posting on TransitMatters' thread?

It is trivially true that anything that TM proposes will be to the exclusion of other tech and modes--but, just as it would not be fair to beat a dog for being the wrong sort of cat, it is wrong to beat up on a fast, cheap, off-the-shelf kit of cat(enary) parts for not being pioneering tech.

I could hijack this thread to sing the virtues of e-bikes as the solution for Zone 1A, AVs, or e-navettes, or whatnot but none would give the TM team the respect they've earned of taking their proposal seriously on it's own terms--a proposal that MA and RI politicians can focus on for immediate planning and procurement cycles.
Thank you!

The battery stuff belongs in either one of the general transit pitch threads (I'd recommend the crazy pitches) or perhaps its own thread, but it is tiresome to see it mucking up this thread.
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Old 05-21-2018, 07:37 PM   #131
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Re: TransitMatters Regional Rail Plan

Without going back to the batteries discussion (and I agree with the request others have made to move that to a separate thread), could I raise my earlier questions about electrification again? Basically just better understanding the pros and cons of third rail vs catenary.

I'm not raising it to try to argue against the current proposal-- I just want to better understand the background.

As I say, there seems to be a large fleet (and presumably suppliers for said fleet) of commuter rail EMUs not far from us. I assume there are very good reasons for not going the route that they have, but I just don't know what they are (beyond the obvious point of not reinventing the wheel).

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Question about electrification in general, and then applied to the T:

Why does Metro-North use third-rail electrification instead of overhead catenary? What are the pros and cons associated with third-rail for regional/intercity systems?

I assume that third-rail does not make sense for the MBTA's Commuter Rail, simply because the infrastructure is already in place for overhead for a sizable fraction of the system, and so there's no point in reinventing the wheel.

(That said, would third-rail be cheaper on a per-mile basis, since it's a rail close to the ground, and not something that requires hundreds of masts be put up?)

I guess, lurking in the back of my mind, is the long-term question-- would third-rail be a better long-term investment than overhead? I seem to recall that one of the (many) reasons for handwringing over Indigofying the Fairmount Line was that there aren't many commercially available EMUs in the US. I assume that assumes overhead electrification, because clearly there are plenty of EMUs down in the Tri-State area that could be used up here, if we had third-rail-- right?
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Old 05-21-2018, 08:46 PM   #132
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Re: TransitMatters Regional Rail Plan

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Originally Posted by Riverside View Post
Without going back to the batteries discussion (and I agree with the request others have made to move that to a separate thread), could I raise my earlier questions about electrification again? Basically just better understanding the pros and cons of third rail vs catenary.

I'm not raising it to try to argue against the current proposal-- I just want to better understand the background.

As I say, there seems to be a large fleet (and presumably suppliers for said fleet) of commuter rail EMUs not far from us. I assume there are very good reasons for not going the route that they have, but I just don't know what they are (beyond the obvious point of not reinventing the wheel).
I hear ya and it's something we discussed at length when forming the proposal. Third rail is simply dangerous for a couple of reasons: at crossings and at grade ROWs (trespassers can get more easily electrocuted). It also introduces maintenance issues regarding general maintenance of the rail, but also weather-related concerns like the need for 3rd rail heaters, which also need regular maintenance. Overhead catenary just made more sense for MA's commuter rail situation and it does align with global precedents. 3rd rail for Regional Rail systems is the anomaly. Most use overhead.
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Old 05-21-2018, 09:38 PM   #133
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Re: TransitMatters Regional Rail Plan

The big issue with third rail is the operating voltage- because it's so close to the ground, it can only operate at around 750V. This means substations every mile and significantly more transmission loss vs overhead wire, which can operate at 14kV easily.
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Old 05-22-2018, 06:28 AM   #134
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Re: TransitMatters Regional Rail Plan

3rd rail was a better choice only in tunnels with low overhead clearances (NYC Park Avenue tunnel) and 100 years ago in an era of lighter wooden cars and when DC hadn't yet lost to AC and most RRs generated their own rather than tapping the grid. The long term penalty of 3rd rail is worth it if it saves you enough money on enough smaller diameter subway tunnel.

New England's High voltage 60Hz AC requires more clearance above, but is lightweight, and delivers high power safely and without need of converters to DC (NY Central/Grand Central) or 25Hz.(Pennsylvania RR). Our wire is world class and ready for upgrading.
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Old 05-22-2018, 12:10 PM   #135
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Re: TransitMatters Regional Rail Plan

Quote:
Originally Posted by Riverside View Post
Without going back to the batteries discussion (and I agree with the request others have made to move that to a separate thread), could I raise my earlier questions about electrification again? Basically just better understanding the pros and cons of third rail vs catenary.

I'm not raising it to try to argue against the current proposal-- I just want to better understand the background.

As I say, there seems to be a large fleet (and presumably suppliers for said fleet) of commuter rail EMUs not far from us. I assume there are very good reasons for not going the route that they have, but I just don't know what they are (beyond the obvious point of not reinventing the wheel).
As others have said -- centenary for safety, easier transmission. Also worth noting, the off the shelf EMUs generally are designed for overhead transmission wires, so it's a good choice for standardization of equipment purchases. Then consider that one of our lines already has cat strung, and it becomes a fairly obvious choice.
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