Tunnels!

Roads - Rails - Sidewalks - Bikeways
StandishGuy
Block E
Posts: 21
Joined: January 29th, 2021, 4:24 pm

Re: Tunnels!

Postby StandishGuy » March 26th, 2021, 9:54 am

In my comments above, I meant Dallas rather than Houston. Here's an article about their $1.7 billion subway tunnel for DART LRT: https://www.dallasnews.com/news/transpo ... as-subway/

By the way I Googled a few stats to compare Dallas & Minneapolis:
Dallas
* Total Population: 1.34+ million
* Population Density: 4,000 per square mile
* Downtown Population: 12,000+
Downtown Workers: 135,000+

Minneapolis
* Population: 435,000+
* Population Density: 8,000 per square mile
Downtown Population: 50,000+
* Downtown Workers: 200,000+

Not saying it makes definitive financial or transit sense to construct a transit tunnel in downtown Minneapolis, but maybe the Met Council should study it- especially if less transit friendly places are moving forward.

alexschief
Foshay Tower
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Location: Philadelphia

Re: Tunnels!

Postby alexschief » March 26th, 2021, 10:32 am

I think it already does. My understanding is that a train every 2.5 minutes (so, 10 minute frequency on two lines) is the absolute max they can get through the downtown stoplights, hence the Blue Line frequency dropping slightly when the Green Line opened in 2014. So I guess it depends on how you define "at capacity" - all the seats being full on a given number of trains per day? All the seats being full and some number of people standing?
FTA defines "at capacity" by calculating (well, the transit authority makes the calculation and submits it to FTA for review) the amount of space per passenger at peak hour and direction. Essentially if you have under 5.7 square feet per passenger at peak, you are considered to be at or approaching maximum capacity, and are eligible for the program.

Don't take these numbers as the gospel, but I did some quick measurements of Metro Transit's vehicles, and estimate that they have about 78 feet by 8.7 feet of passenger space on every train. So 678.6 square feet of passenger space, divided by 5.7 square feet per passenger, would suggest that Metro Transit would need to (1) achieve passenger density of 120 people per train (2) throughout the designated peak hour (3) throughout the downtown trunk to qualify for the program. Or, if you prefer numbers in the aggregate, since Metro Transit runs 12 three-car trains per hour in one direction on the downtown, that means that it would need to average 4,286 riders in the peak hour in the downtown trunk (= (678.6 x 3 x 12)/5.7 ).

Pre-pandemic did Metro Transit already do this? I'm not sure. The cumulative boardings per day at the five downtown trunk stops in Q3 of 2019 was juuuust under 20,000. Without having a better sense of the distribution of these boardings, it's impossible to say, but it's certainly plausible that Metro Transit has hit this capacity metric, or will hit capacity when the SWLRT is complete. Then again, because the capacity metric takes into account travel in a single direction, perhaps not. It's tricky!

In terms of increasing capacity by 10%, the best way Metro Transit could meet this requirement is to explain that running at-grade limits frequencies on both lines to a train every 10 minutes, and a train every 5 minutes in each direction on the downtown trunk. Running underground could improve capacity from 12 trains per peak hour to 16 trains per peak hour (and much higher than that, but then these lines will be limited by signals elsewhere in the system, so 3.75 minute headways in the downtown trunk seems a reasonable goal).

Again though, I'm interested to see what congress will do, because I'm not sure the Core Capacity part of the CIG program is working as intended? Just browsing the list of current CIG projects and I see only two Core Capacity projects. That seems like too few, there are major core capacity needs across the country. More funding and perhaps a loosened eligibility to allow funding for smoother operations untied to capacity numbers, might be helpful. It may also be important to revise assumptions about peak hour travel if downtown working behavior changes post-pandemic.

Trademark
Nicollet Mall
Posts: 136
Joined: March 31st, 2019, 11:22 am

Re: Tunnels!

Postby Trademark » March 26th, 2021, 2:48 pm

Two extensions will definitely increase boarding downtown

DanPatchToget
Foshay Tower
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Re: Tunnels!

Postby DanPatchToget » March 27th, 2021, 9:53 am

Not that the regions are comparable, but Los Angeles has the Regional Connector project consisting of a tunnel under Downtown LA that will allow through-routing for the A Line (Blue) and E Line (Expo).

twincitizen
Moderator
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Re: Tunnels!

Postby twincitizen » March 27th, 2021, 5:01 pm

Not that the regions are comparable, but Los Angeles has the Regional Connector project consisting of a tunnel under Downtown LA that will allow through-routing for the A Line (Blue) and E Line (Expo).
Some great videos of that project: https://www.youtube.com/user/losangeles ... =connector

For those that don't know, the Regional Connector is a "$1.55 billion 1.9-mile light rail subway" including 3 new underground stations, to give an idea of what it might cost to build something like that in Minneapolis.

Trademark
Nicollet Mall
Posts: 136
Joined: March 31st, 2019, 11:22 am

Re: Tunnels!

Postby Trademark » March 27th, 2021, 5:50 pm

Not that the regions are comparable, but Los Angeles has the Regional Connector project consisting of a tunnel under Downtown LA that will allow through-routing for the A Line (Blue) and E Line (Expo).
Some great videos of that project: https://www.youtube.com/user/losangeles ... =connector

For those that don't know, the Regional Connector is a "$1.55 billion 1.9-mile light rail subway" including 3 new underground stations, to give an idea of what it might cost to build something like that in Minneapolis.
I lived in LA for most of last year and I know that the Regional Connector project has been horrendously mismanaged and delayed which has added greatly to the costs. For the downtown mpls tunnel it would probably only need to be about a mile considering a US bank to target Field alignment. Even with inflation i think $600 million for that one mile is definintly doable with underground stations at Hennepin/nicollet and government center

DanPatchToget
Foshay Tower
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Joined: March 30th, 2016, 1:26 pm

Re: Tunnels!

Postby DanPatchToget » March 27th, 2021, 6:52 pm

The main issue I see with tunneling the light rail in Downtown Minneapolis is the existing alignment is elevated (sort of) at Target Field Station. With I-394 underneath where could a tunnel portal be built on the western end?

Trademark
Nicollet Mall
Posts: 136
Joined: March 31st, 2019, 11:22 am

Re: Tunnels!

Postby Trademark » March 27th, 2021, 7:51 pm

The main issue I see with tunneling the light rail in Downtown Minneapolis is the existing alignment is elevated (sort of) at Target Field Station. With I-394 underneath where could a tunnel portal be built on the western end?
That's why I never include Target Field as an underground station. I see the portal beginning at 2nd Ave N and running east to Park Ave.

tmart
Rice Park
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Location: Expat

Re: Tunnels!

Postby tmart » March 28th, 2021, 9:18 am

The main issue I see with tunneling the light rail in Downtown Minneapolis is the existing alignment is elevated (sort of) at Target Field Station. With I-394 underneath where could a tunnel portal be built on the western end?
An idea that's maybe less crazy than it initially sounds would be to remove the last few ramps of 394 (3rd, 4th, and Washington) so that a subway could continue all the way to Target Field Station, with the portal between 2nd Ave N and the current platforms.

The MNDOT AADT map says the 2019 usage for the whole Downtown segment of 394 is 36000; I imagine a huge portion of that traffic gets off at the A/B ramps or 6th St., so the traffic impact from removing the last couple ramps might actually affect only ten thousand cars per day, quite manageable in the grand scheme of things. (It would be nice to have data on each individual ramp to confirm that.)

My concern with a portal east of 2nd Ave N is that, if the goal is to improve capacity, it would seem ideal for the grade separation to last the entire length of the segment that's shared between the Blue and Green Lines. Any at-grade crossing where the Blue and Green Lines are interlined would probably end up being the limiting factor for the whole system.

Trademark
Nicollet Mall
Posts: 136
Joined: March 31st, 2019, 11:22 am

Re: Tunnels!

Postby Trademark » March 28th, 2021, 11:09 am

The main issue I see with tunneling the light rail in Downtown Minneapolis is the existing alignment is elevated (sort of) at Target Field Station. With I-394 underneath where could a tunnel portal be built on the western end?
An idea that's maybe less crazy than it initially sounds would be to remove the last few ramps of 394 (3rd, 4th, and Washington) so that a subway could continue all the way to Target Field Station, with the portal between 2nd Ave N and the current platforms.

The MNDOT AADT map says the 2019 usage for the whole Downtown segment of 394 is 36000; I imagine a huge portion of that traffic gets off at the A/B ramps or 6th St., so the traffic impact from removing the last couple ramps might actually affect only ten thousand cars per day, quite manageable in the grand scheme of things. (It would be nice to have data on each individual ramp to confirm that.)

My concern with a portal east of 2nd Ave N is that, if the goal is to improve capacity, it would seem ideal for the grade separation to last the entire length of the segment that's shared between the Blue and Green Lines. Any at-grade crossing where the Blue and Green Lines are interlined would probably end up being the limiting factor for the whole system.
Closing traffic to Washington would probably be a tough sell especially with North Loop exploding. Plus that would put a lot of Northeast mpls bound traffic on more congested streets like hennepin farther up where they mix more with general downtown traffic.

I agree that at grade crossings are a problem but I think that could be solved pretty easily by getting rid of the 394 ramp at 3rd ave N. I assume most of the traffic could just get on at Washington. You could still keep the entrance ramp to Ramp B for buses but just make it a gated crossing. With little bus traffic entering that way it shouldn't be too difficult.

I 100% agree with closing the 4th Street ramps. If that is done 394 could easily become a 2 lane highway with a jersey barrier. And that could provide enough room for the train to descend between 3rd and 2nd. (They might have to dig the trench a little bit deeper but that shouldn't be as difficult since they wouldn't have to make the 4th Street ramps connect anymore) There could even be room for a light rail in the trench going Northeast and down lyndale to uptown.

Anondson
IDS Center
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Re: Tunnels!

Postby Anondson » March 28th, 2021, 12:01 pm

Closing traffic to Washington would probably be a tough sell especially with North Loop exploding. Plus that would put a lot of Northeast mpls bound traffic on more congested streets like hennepin farther up where they mix more with general downtown traffic.
Cutting through downtown to cross the city makes downtown less pleasant.

It is good policy to make traffic coming off 394 to get to NE cutting through downtown instead divert around to Broadway, Plymouth, University.

Trademark
Nicollet Mall
Posts: 136
Joined: March 31st, 2019, 11:22 am

Re: Tunnels!

Postby Trademark » March 28th, 2021, 12:33 pm

Closing traffic to Washington would probably be a tough sell especially with North Loop exploding. Plus that would put a lot of Northeast mpls bound traffic on more congested streets like hennepin farther up where they mix more with general downtown traffic.
Cutting through downtown to cross the city makes downtown less pleasant.

It is good policy to make traffic coming off 394 to get to NE cutting through downtown instead divert around to Broadway, Plymouth, University.
If someone is coming from St Louis Park to St anthony. How will they most likely make that trip. Broadway is way out the way. There is no access to plymouth from 394 and during rush hour the turn onto 94 east is one of the worst congestion points in the city. Yes I would like it if people didn't go thru downtown. But there isn't many good alternatives.

The alternative im presenting is in response to the suggestion provided. I'm not making a new ramp. Washington avenue already exists. I agree with you. We should keep traffic out of downtown. Forcing all 394 traffic into one choke point on 6th street congesting the heart of downtownakes that problem much worse. What I am proposing is just getting rid of the 4th Street exit. And reclaiming a good portion of the trench where the 4th Street exits currently exist.


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