Downtown Minneapolis LRT Tunnel Discussion

[Anondson]

The Rosalyn station of the DC metro is a little more than 100 feet deep.

I remember it being one long 3 minute single escalator ride. It also has banks of elevators to get you down in less than 20 seconds.

[thespeedmccool]

D.C. Metro has a ton of deep stations, especially along the Red Line. One station, Forest Hills, is elevator access only. Like a dozen have multi-minute long escalator rides.

[pannierpacker]

D.C. Metro has a ton of deep stations, especially along the Red Line. One station, Forest Hills, is elevator access only. Like a dozen have multi-minute long escalator rides.

Wow, now that's a drop!
https://youtube.com/watch?v=byiunSQ10c8

Apparently the whole system is this deep because the soil becomes 'unstable' between 100' and the surface?

[luigipaladio]

I love subways and tunnels, but they can be alarmingly expensive. To get to the depth of the sandstone under downtown, the tunnels on either end of that stretch would have to start far beyond the downtown area to minimize steep grades on the approaches to either end of the tunnel. The stations themselves, would either have to be much fewer in number, making the system less accessible. The possible subterranean corridors through downtown are tight. Minneapolis downtown is not as tight as St. Paul, but most of the cross town streets are relatively narrow. Construction would be in many cases right up against the foundations and pilings of major buildings.

PBS ran a NOVA program on the new Elizabeth Line in the London Subway system which isn't a fair comparison because it is so big, but the cost overruns and delays were phenomenal - $25 billion, eleven years - and a really spectacular new subway line - with some long surface running to Heathrow.

Space wise, stations for an underground system take up a huge volume of space because of the need for vertical circulation as well as the train lines. It's a great idea, but I think our downtown area is too small to make it work well.

[Beachclub]

If the problem is conflict between cars and LRT in the downtown core, isn't the solution just to ban cars from the downtown core? There are examples of cities larger and smaller than Minneapolis making their downtowns car free, and they have all been successful (I think).

I mean, why even mess with a tunnel? It would be cheaper and easier to implement a car ban than to build even a shallow tunnel AND it would improve the pedestrian experience, which downtown desperately needs. I know that the political will isn't there right now, but I'll bet it would easier to implement politically than an expensive tunnel (especially considering the Blue Line extension tunnel debacle and the fact that the mayor seems to be proposing some sort of car-free entertainment district anyway...)

[VacantLuxuries]

I've always thought the biggest barrier to a downtown tunnel would be that you'd probably have to lose the Hennepin/Warehouse station for the portal, considering that the tracks would have to rise above the underground portion of 394 to reconnect with the first Target Field platform.

[MNdible]

I'd argue that Hennepin and Nicollet should be consolidated anyway, but the problem remains dipping down quickly enough to not sever First Avenue. In theory, it's maybe doable -- about 400' of run between First and Second to drop about 20' puts you at a 5% grade, which I think is towards the upper end of what's acceptable.

You'd still need to get over to Sixth Street somehow (probably under the parking lot by Gluek's so you have some room to soften the curves). And even if you can figure that out, you're still breaking the entire LRT system for as long as it takes you to build the portal.

[Tom H.]

Apparently the whole system is this deep because the soil becomes 'unstable' between 100' and the surface?

Well, that, and because it makes for tons of fun exploration in Fallout 3

[BigIdeasGuy]

2nd Ave is roughly 5 feet lower than 1st Ave which is definitely helpful

[Hero]

I kinda like the idea of a skyway level stations. Maybe have them over intersections so buildings on the corners would have access.