Untangling Spaghetti Junction

Lady looks intimidated

I capped my last post with an image of the insanely overbuilt Spaghetti Junction in Louisville, but we have our own Spaghetti Junction here, and while it may not be as monstrous, it is still quite the tangled bowl of noodles.  A while back, I color-coded it for ease of understanding where all those wacky ramps are going:

Thatza spicey meat-a ball!

This effort grew out of my plan for a pedestrian-friendly West Bank, one of the centerpieces of which was the conversion of Cedar Ave to a transit mall.  Unfortunately the Minnesota Highway Department – oh, excuse me, MnDOT – thinks of this pedestrian-scaled neighborhood as nothing more than an over-metered access ramp between 35W and 94.  So I tried to think of a way to connect the highways and make the poor, marginalized motorists happy.  It didn’t really work:

L'étoile du Défaite

I called my effort Hermann Circle, after Hermann Olson, longtime mad City Planning Engineer for Minneapolis whose initial sketches for Hwy 62 included roundabouts at intersections (or at least one did).  Although there is a lot of space in Spaghetti Junction (enough for at least a 400′ diameter roundabout) the alignment of the highways make for some very tight entrances.  Also there’s the probably that the amount of traffic going through all these ramps would gridlock the circle as soon as the clock turned 7:01 am, although I’d think that could be solved with signals metering entrances – if almighty convenience can be sacrificed for mobility.

You’ll notice that I didn’t try to make the connection from southbound 35W to eastbound 94.  That’s because a route exists that actually provides a better alternative than Cedar Ave (the closure of which is my purpose for this whole exercise) – the existing route through congested and, by all rights, pedestrian-owned Cedar is about .7 miles.  A route that follows Washington Ave to 11th Ave S to 6th St S and its long, winding ramp to eastbound 94 is only .6 miles on local streets and has 6 fewer stoplights to interfere with your God-given automotive freedom.

The circle didn’t work, but luckily there’s an easier way.  My proposal for the West Bank trench would allow a much simpler connection for westbound 94 to northbound 35W.  A ramp could simply branch off the existing ramp from westbound 94 to 5th St S, slope downward and join the existing ramp from northbound 35W to the Washington Trench and environs:

The new ramp is in red

It looks tight, and it is, but the space between these ramps is 55 feet at the narrowest, and the 1-lane ramp would be 25 feet, tops.  The trickiest part is the angle at which the new ramp would meet the existing ramp, which might require a new bridge for the ramp from westbound 94 to 5th St S.  Here is a view of the new ramp in my Spaghetti Junction diagram, which may or may not make things clearer:

Somewhere you'll find a connection is made

I’m not aware of anyone else having proposed this ramp, and for a good reason – it couldn’t exist as the Washington Trench is currently configured since the ramp from 35W northbound (to which I would join the new ramp from 94) currently splits into 3 lanes and, more important, does not reconnect to 35W.  My proposal is predicated on my idea to build a two-way ramp between the Trench and the normal Washington, from which traffic could then proceed to northbound 35W.  In addition my Trench idea would remove the flyover ramps and instead funnel all traffic to an intersection at the Trench, clearing up space for a ramp from 94 to join in.  I haven’t crammed enough crappy Visio diagrams into this post, so here’s one of my Trench proposal:

Greater connectivity, but at-grade.

In 2007, MnDOT released their Downtown Minneapolis Freeway Study, which can possibly be considered a textbook case of cluelessness (page 1 of the Executive Summary: “the [35w Mississippi River] bridge is in good condition and could remain in place with regular maintenance until 2020 or later.”).  The mission was to look at the feasibility of expanding the downtown freeway capacity to the degree that it could achieve a level of service D/E in 2030.  Assuming the costs of Milwaukee’s tunnel-less Marquette Interchange ($25m/lane-mile), the study estimated that it would cost from $1.1 billion to more than $2 billion to complete an upgrade that would include nearly doubling the width of the Lowry Tunnel:

Really? Less than $2 billion?

MnDOT’s “vision” for Downtown freeways also included direct connections between 35W and 94 somehow.  I haven’t been able to find the details, and the closest thing to an image I’ve seen is a modification by Froggie.  I hope he doesn’t mind me copping it:

Froggie's mods

Keep working, Lady

So there are lots of ways to untangle Spaghetti Junction, but most are very expensive and some are just not feasible.  Seems like Minnesotans are just going to have to keep driving through it and Lady will just have to keep slurping.

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7 comments on “Untangling Spaghetti Junction

  1. Bill says:

    screw all this. why don’t we just use our MNDOT tax money to buy a big rocket and shoot it into the moon?

  2. mulad says:

    I’ve had a thought of combining the on- and off-ramps for I-94 into a single ramp terminating at 6th Street, though I’m not sure if converting 6th into a two-way would have enough capacity. Maybe it’d work with dynamic center lanes that change direction (though I’d be leery about doing that, considering how fast most people try to go until the last second as the get off of I-94 today…). But anyway, that would definitely create enough room for the I-94/I-35W connector.

    Froggie did something vaguely similar, making the off-ramps from I-94 and MN-55 merge together and land at 7th Street, though his plan reused the 5th Street ramp as a local road connecting to 15th, 16th, and 17th Avenues.

    • Froggie says:

      Sorry for jumping in so late here…

      My concept was based in part on a conceptual design MnDOT did in 2007 and in part on the Access Minneapolis study the city did. The city proposes, as I do, two sets of east-west one-way streets, specifically 3rd/4th (direct connections to I-94 and I-394 on the west and to the U of M on the east, with proposed ramps to 35W North) and 6th/7th (both have ingress/egress on each side of downtown). 5th is taken out because of the LRT, which is why everyone proposes moving the ramp from I-94 to merge onto 7th. 8th is effectively out because of the way the 7th St Garage and other ramps were configured when I-394 was built (the reason eastbound 55 followed 10th St until it was rerouted onto I-94 around downtown). I could also see the city retaining 11th/12th as a one-way pair because of how they connect to 35W south and 394. But this leaves the door wide open for converting 8th (at least west of 11th Ave), 9th, and 10th (at least east of Hennepin) to 2-way operation.

      I should probably revise my map considering the changes to U of M access and also to clean it up (i.e. highlight the actual overpasses).

  3. Alex says:

    Are you thinking 6th would be a two-way all through Downtown, or just until Chicago like today? I think the E-W Transit Spine study’s finding that converting 8th to two-way would have a minor effect on operations implies that the impact of 6th as a two-way would also be minimal. Seems like convertible lanes work in lots of places, but I don’t about on freeways, and I wonder if it could be done while retaining the HOV lane.

    The city’s position as adopted in the Downtown Action Plan is to replace the 5th St I-94 ramp with 7th St – and I like Froggie’s suggestion to reuse 5th as a local connector.

    • mulad says:

      Yeah, I would have just had it two-way until Chicago. I was just being a bit cautious in my thinking — if the street can handle the traffic, then just go ahead and make it two-way without the direction switching. And if it can handle the traffic that far, it probably wouldn’t hurt to keep it two-way all the way into the core of downtown.

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