Green Line LRT

Roads - Rails - Sidewalks - Bikeways
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TommyT
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Re: Green Line (Central Corridor LRT)

Postby TommyT » June 26th, 2014, 8:55 am

So I'll admit I've only ever had the need to ride LRT about 4 times since I moved here in 2006, and I always purchased a ticket. What I'm wondering is how do they count ridership for those with MetroTransit cards? Do you still have to scan the card somewhere like you do on the bus?

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Re: Green Line (Central Corridor LRT)

Postby Tcmetro » June 26th, 2014, 9:10 am

There are GoTo card scanners at each station. I also believe that all the trains are equipped with automatic passenger counters, which is basically a sensor that counts all boardings and alightings.

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Re: Green Line (Central Corridor LRT)

Postby mulad » June 26th, 2014, 9:41 am

Yeah, I call them "pedestal readers", though I'm not sure what the official name is. The new ones at the Target Field expansion and along the Green Line stations seem to be a slightly thinner (shallower) version than the old ones, but they all look basically the same:

Image
img_8420-edit by Mulad, on Flickr

In contrast, if you're buying a ticket with cash or credit card, or adding value to an existing transit fare card, you'd use a big ticket vending machine (TVM). However, as far as I can tell, you can't deduct from a fare card to pay for a ride with one of these [not my photo]:
Image
Metro Transit Ticket Vending Machine by TheTransitCamera, on Flickr

You're always supposed to tap your fare card whether starting a new journey or continuing with a transfer. That's different than using a mag-stripe ticket, where it gets inserted into the farebox on a bus, or you can just carry it with you on the train as proof-of-payment. I think they want people to always tap their cards at rail platforms so they can get a relatively reliable stream of data to compare against any automatic counters they may have, since the mag-stripe tickets don't get counted directly (except for tickets purchased at TVMs at the start of a trip).

There isn't a huge reason to have people tap their cards all the time other than to collect data, but it does give the benefit of telling you if your fare is still valid. A regular mag-stripe ticket has its expiration time stamped on it, but you can't just look at your Go-To card and know what the transfer window is. From that perspective, it's good to just tap it all the time, so you don't get caught paying a fine later.

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Re: Green Line (Central Corridor LRT)

Postby EOst » June 26th, 2014, 11:03 am

I was sitting in a Green Line train at Stadium Village that seemed to be stuck somehow. They got it moving after maybe 15 minutes, but it'll be a big delay down the line

The actual ride from there to Snelling was alright, only had to stop at lights twice. The surprising one to me was Cromwell, where we were stopped for at least a minute.

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Re: Green Line (Central Corridor LRT)

Postby MSPtoMKE » June 26th, 2014, 4:08 pm

mulad wrote:There isn't a huge reason to have people tap their cards all the time other than to collect data, but it does give the benefit of telling you if your fare is still valid. A regular mag-stripe ticket has its expiration time stamped on it, but you can't just look at your Go-To card and know what the transfer window is. From that perspective, it's good to just tap it all the time, so you don't get caught paying a fine later.
I don't know if it is only at the new stations, but recently when I have touched my GoTo card to a pedestal reader and have looked, it always tells me my transfer expires in 2.5 hours from that point, even if I had an existing transfer on the card from a previous trip. I don't actually get they extra transfer time that it tells me, however. So that seems like a glitch.
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Re: Green Line (Central Corridor LRT)

Postby mulad » June 26th, 2014, 5:16 pm

Interesting. I'll have to watch out for that and will send Metro Transit a note if I see anything. I think my transfers have been expiring properly, so it might just be a display issue. Also worth doing an extra read of the card before/after to see how that looks (I think you press the "B" button before tapping).

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Re: Green Line (Central Corridor LRT)

Postby Minneapolisite » June 26th, 2014, 9:00 pm

Today I rode the bike lanes from Koplin's to Prior and cut over to Fresonia (sp? Nice curvey residential street) to the Fairview Station. Train was 6 minutes late and went fast enough until East Bank where there was an announcement it would be there for 5 minutes, so I left and rode through campus to the ped-bike bridge along the riverfront trail into Downtown. Nice to have been able to take bike lanes/trails virtually all of the way. Gotta love multi-modal transportation: when one doesn't quite work out you can choose something else.

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Re: Green Line (Central Corridor LRT)

Postby mulad » June 27th, 2014, 8:08 am

According to F&C, the busiest stations in the first week were Nicollet Mall (9% of rides), East Bank (9%), Snelling (7%), and Central in downtown St. Paul (7%).

http://finance-commerce.com/2014/06/the ... reen-line/

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Re: Green Line (Central Corridor LRT)

Postby MinnMonkey » June 27th, 2014, 9:27 am

I don't get it. It seemed like the signaling issues was getting better all week, but today it was back to square one. Leaving downtown Minneapolis we needed to stop for signals at the following intersections:

- Church Street
- Union Street (should never need to stop here)
- Walnut
- Oak
- Ontario
- Huron
- 25th Ave
- Bedford
- Berry
- Eustis

I got off at Raymond.

The operator ended up going through at least 2 horizontal bars that I could see because they were not changing. Overall the trip was 40% longer than the schedule stated.

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Re: Green Line (Central Corridor LRT)

Postby David Greene » June 27th, 2014, 9:50 am

94 was closed for the President so I took the opportunity to travel along University from 3rd Ave. to Robert St. We met up with a train at Malcolm and we basically stayed neck-and-neck. We only stopped at Eustis but after the Raymond station we left the train in the dust. All of the signals were timed perfectly had the train not had to stop at the Raymond station (or anywhere else along the line). We had very few stops the rest of the way along University. In fact a westbound train stopped at the Rice St. crossover so we could go through.

It's abundantly clear that the signals are timed for cars, not trains.

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Re: Green Line (Central Corridor LRT)

Postby MNdible » June 27th, 2014, 10:01 am

Or, it could be that cars are benefiting from their imperfect attempt to better time the lights for trains. At this point, the only thing that's abundantly clear to me is that it isn't working like they want it to.

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Re: Green Line (Central Corridor LRT)

Postby VAStationDude » June 27th, 2014, 11:32 am

I just rode from Hennepin to Western. Ended up being two minutes behind schedule. Not disputing the poor experiences. I just had a great one. We did end up waiting way too long at Vandalia and Prior.

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Re: Green Line (Central Corridor LRT)

Postby mulad » June 27th, 2014, 11:36 am

I'm not sure how things should go on the UMN campus, but along University Avenue, it seems like the cars get a green wave that moves pretty fast, perhaps over 30 mph. With stops, the train would average 20 to 25 mph if it wasn't encumbered by signals. So really, the green wave along University should be set to match the train's average speed, and it would probably glide through nicely even if the signal priority system was broken.

When the signal priority system is working, it's probably okay to have cars normally getting a ~30 mph green wave, but things need to change as a train comes along, otherwise it will frequently miss cycles down the road. A train burns up about 45 seconds slowing, stopping, and accelerating again, compared to going straight through. For the far-side station platforms, I suspect the ideal would be for the train to pull through the intersection and arrive at the station just at the end of a green phase for cars. The 45-ish seconds lost at each stop can be given to cross traffic for the next couple of intersections ahead of the train, and then as the train departs the station, there should be a green wave set up to the next station (2 to 4 intersections down the street) that goes at about 25 mph or maybe slightly less. For cars that make it through the intersection at the next stop along with the train, it may be possible for them to get onto a green wave cycle down the line that continues at 30 mph.

My experience has very, very frequently been that the train makes it to an intersection 10 to 20 seconds too late for this to work right, and having a green wave for cars of 30 mph or a bit faster could easily make that happen. From the perspective of good urbanism and pedestrian safety, we probably want lights set up to encourage cars to go 20 to 25 mph anyway, so I don't know what the big problem is, aside probably from traffic engineers trying to hit certain level-of-service/speed targets for cars.

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Re: Green Line (Central Corridor LRT)

Postby mister.shoes » June 27th, 2014, 11:49 am

How much is this complicated by the fact that trains run both directions? You can't give both an eastbound and a westbound green wave simultaneously. Hrm, now that I think about it, the 10 minute headways should be more than enough time for those waves to overlap and reset.
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Re: Green Line (Central Corridor LRT)

Postby at40man » June 27th, 2014, 11:59 am

I'm not too familiar with traffic light technology, but it seems like if it were possible to network these signals all together, it would be a much better way to coordinate and time the signals appropriately. Does anyone know if these operate independently of each other or if they are linked?

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Re: Green Line (Central Corridor LRT)

Postby David Greene » June 27th, 2014, 12:46 pm

at40man wrote:I'm not too familiar with traffic light technology, but it seems like if it were possible to network these signals all together, it would be a much better way to coordinate and time the signals appropriately. Does anyone know if these operate independently of each other or if they are linked?
This is a classic question in computing: do you try to synchronize things globally for optimal performance or do you decouple them and let them run independently, reacting as local conditions change? Honestly, there is no right answer that works everywhere. It's a very problem-specific thing and I would not be surprised if the same is true for signal engineering.

The aspect I hadn't appreciated before is the pedestrian interaction. It's unpredictable and imposes a fixed delay on any signaling down University. It's easy to locally preempt crossing auto traffic. Not so with pedestrians. Some communication between ped signals and nearby traffic/train control seems necessary to reduce the unpredictability of the pedestrian component. You'd want the ped signal to be aware of the train far enough away to cover the time necessary to block University traffic, about 4-5 blocks on each side perhaps.

Incidentally, these kinds of challenges are *exactly* why PRT will never work in the real world the way its supporters claim.

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Re: Green Line (Central Corridor LRT)

Postby David Greene » June 27th, 2014, 12:52 pm

David Greene wrote:This is a classic question in computing: do you try to synchronize things globally for optimal performance or do you decouple them and let them run independently, reacting as local conditions change? Honestly, there is no right answer that works everywhere. It's a very problem-specific thing and I would not be surprised if the same is true for signal engineering.
I would not be surprised at all if the problem is NP-complete (i.e. not generally solvable by standard computers). It certainly has that feel to it. If it is NP-complete, then heuristics is one of the tools available but they are going to get you into pathological situations from time to time. They should be tunable to perform well generally, though.

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Re: Green Line (Central Corridor LRT)

Postby Didier » June 27th, 2014, 1:13 pm

This thread moves fast, so this might have been brought up already, but the University-Huron intersection is a total mess with the signaling. I ate an entire slice of Mesa pizza waiting for the eastbound light to turn green.

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Re: Green Line (Central Corridor LRT)

Postby mulad » June 27th, 2014, 1:21 pm

I think they must be networked together, based on the behaviors and sequencing I've seen, but that could just be from the detectors they use.

I mostly ponder the 5 stations from Snelling to Western, and for those, I think the ideal solution for bi-directional trains would involve getting the trains to arrive at the station almost simultaneously, passing through the intersection at the same time. That's helpful for cars too, since it minimizes the amount of time that the busy cross streets at Snelling, Lexington, and Dale would be held up. Trains have been meeting each other at those intersections by accident now because of the poor signal timing (they may not arrive at the same time, but they end up traveling through together once the light changes). For other scenarios, it seems like it's pretty hard for a pair of trains to avoid getting stuck at a light shortly after passing each other -- it all depends on how long you're willing to stretch, shrink, or rearrange phases.

I don't think the pedestrian phases are unpredictable -- they have a set amount of time, just like what's typical for cars. It's just that there's a limit to how far you can shrink them down, and that limit is bigger than what you'd have for cars. Setting the pedestrian signals to always activate would make them more predictable rather than less (though it probably narrows the window of time that a train has to pass through an intersection or series of intersections).

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Re: Green Line (Central Corridor LRT)

Postby nate » June 27th, 2014, 1:24 pm

It seems to me like the simplest system would be to equip the trains with signal-preemption devices that would only be used if it was running behind schedule. It isn't critical that the trains hit a green wave and fly through the line as fast as possible...it's that they stay on schedule and don't get bogged down stopping at streets like Mackubin.


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