Frank-Lyn – Thinking About Streets and Places in Three Dimensions

The development at the intersection of Franklin and Lyndale Avenues in Minneapolis has gotten a lot of attention, but primarily because of buildings proposed at the corners, to replace under-developed buildings at this highly accessible, emerging locale.

The intersection itself has gotten little consideration. It is an at-grade 4-way traffic signal. However, Franklin Avenue finds itself in a valley at Lyndale, such that a 3-dimensional option presents itself.

Urbanists are often aghast at the notion of highway overpasses in cities, and certainly most have been done poorly with no respect for urban form. But that is no reason to throw out the concept altogether.

Using my extensive computer drafting skills, I present two diagrams. The Plan view (from above) and Side view (facing west) illustrate a concept in cartoon fashion. These are, as they say, not-to-scale and obviously not engineering diagrams.

Frank-Lyn conceptual reconfiguration -  Plan View

Frank-Lyn conceptual reconfiguration – Plan View

The top diagram shows how the middle two lanes on Franklin Avenue (the left lanes Eastbound and Westbound) bridge over Lyndale Avenue (the blue bar represents the bridge). Since there are already two lanes, additional land required is only for bridge barriers, and hopefully that is minimal. Lanes can be narrowed as necessary.

This does several things. It gets cross-traffic on Franklin (going to or from Hennepin mostly) off of Lyndale. This reduces pressure on Lyndale itself, reduces traffic delay, reduces pedestrian delay, reduces bicyclist delay, reduces pollution at the intersection, reduces street crossing times for pedestrians on Lyndale going North or South (there are two fewer lanes to cross). A median boulevard could be added to Lyndale (the green bars).

The intersection of Franklin and Lyndale thus becomes an urban diamond.

There would be an option to eliminate some or all left turn movements as well, and make Lyndale more Boulevard like with no at-grade cross traffic from Franklin. The intersection could be just right-in/right-out for motor vehicles. Pedestrians could be given a Hawk signal if they wanted to cross Lyndale, with a median refuge island. The purple bar shows this region.

The downside is making it more difficult to access businesses on Lyndale (e.g. The Wedge Co-op) which are already difficult to access by car.

But even if there were left-turns allowed, traffic would be much lighter at the intersection.

Franklin Avenue at Lyndale Avenue looking Westbound (side view)

Franklin Avenue at Lyndale Avenue looking Westbound (side view)

The second diagram shows a Side view / cross-section. The idea here is not the particular architecture or building heights, but to illustrate that just because there is a 2 lane overpass, the underside of the bridge can have a pedestrian serving business (that is no more than 26 feet wide). (This need not be a cafe, but in every urban rendering I have ever seen, there are cafes, so there must be a reason).

Previous posts have discussed the underside of bridges before (1) (2). We don’t do this well here, but it doesn’t mean it can’t be done well.

Most intersections are not situated such that 3-dimensions is such a natural solution, but there are some, and we should consider the possibilities.

Full disclosure: I don’t live very near there, and only use the intersection occasionally as a motorist.

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12 Responses to Frank-Lyn – Thinking About Streets and Places in Three Dimensions

  1. Monte Castleman
    Monte Castleman September 15, 2014 at 9:01 am #

    I’ve long thought this would be a good idea at Hiawatha and 46th, a tight diamond would be easier to cross than Hiawatha is now, and it would fix one of the worst traffic problems on Hiawatha.

    The suburbs aren’t exactly comparable because we’re dealing with wide suburban roads more than city streets, but North St. Paul wanted (and got funding for) sinking down MN 36 into a trench with overpasses to make it easier to get across from one half of the town to the other. Elk River wants to do the same thing, while consolidating the highway and the rail corridor.

  2. Matt Steele September 15, 2014 at 9:06 am #

    Even though I proposed this same idea a couple of months ago for a bicycle bridge in this spot, I imagine either a bike bridge or a traffic bridge would be immensely ugly even if it was done better than the 94 flyovers a block north. I just can’t imagine it would be worth it, considering how expensive it would be.

    We could save so much money, and build stronger neighborhoods, if we stopped carrying about “traffic” and how fast automobiles can get through an intersection. Especially in a neighborhood such as this.

    • Sam Newberg
      Sam Newberg September 15, 2014 at 12:05 pm #

      David’s disclosure about not living near the Franklin Lyndale intersection, and thus only occasionally using it as a motorist, is quite revealing. I think this is a common and quite deep problem in urban planning overall and transportation planning in particular – first impressions of places are often from behind a windshield, and thus

      Must agree with Matt on this one. Let’s save the expense of building more bridges. The problem with traffic congestion is too many cars, and we must stop considering that giving them more space to move quickly is a good idea. We can build cities for people or cities for cars, but not both.

      But David, you raise an interesting challenge – where are examples of good urban places that happen to be under bridges? Maybe we need a photo contest – I suspect the list is very short. Hiawatha and Lake have struggled with this since the overpass was built, and the solution would be to not have a bridge at all.

      • David Levinson
        David Levinson September 15, 2014 at 12:45 pm #

        This is a classic first best/second best problem. We might think cars don’t belong in cities, but recognize we are not going to win that argument here (near a freeway on-ramp) any time in the next half-century. What is the next best thing you can do given there are cars? It is not terribly pleasant all around in its current configuration (I have actually crossed it on foot, though don’t do that but once a decade or so, because, you know, why would I, or anyone, with choice in the matter), and reducing the number of pedestrian-vehicle conflicts is good for both pedestrians and vehicles, and reduces delay for both classes of travelers.

        I will grant that the aesthetic judgment of bridge engineers has historically been lacking, but that doesn’t mean it must be so. I like the examples in my and Reuben’s earlier posts, but am sure there are a few more that are acceptable.

      • Nathanael September 21, 2014 at 11:03 pm #

        The only good urban places I know under bridges are under old-style masonry arch bridges (where shops fill in the arches). And I know of very few of them.

  3. Adam Froehlig
    Adam Froehlig September 15, 2014 at 9:18 am #

    I like the concept, but there are two potential issues that would cause some difficulty.

    The first issue isn’t insurmountable, but may create some local aesthetic concerns, and that relates to the height of the bridge. Per LIDAR-derived contour data, the Franklin/Lyndale intersection is at an elevation of about 861ft. Franklin/Aldrich to the west is about 876ft, while Franklin/Garfield to the east is about the same…876ft.

    The minimum standard bridge clearance these days is 16ft (17ft is preferred). Add about 4ft for the bridge substructure (beams, deck thickness, etc). So that would effectively make the bridge deck 20ft above Lyndale, or 4ft higher than the adjacent intersections on Franklin. As I mentioned before, this isn’t insurmountable by any means, but it would require a slight rise on each bridge approach in order to keep the adjacent intersections open.

    Alternatively, since Franklin continues rising in each direction, a “straight across” bridge could also be built without any rise in the center and still provide adequate clearance on Lyndale. But this would require converting both Aldrich and Garfield to right-in/right-out only on Franklin. In the case of the Wedge, their only full access point in and out would be at Franklin/Bryant, which IMO is too close to the Franklin/Hennepin intersection.

    The second issue is the bridge abutments, which at an absolute minimum would need to be 25ft in width. Franklin’s existing street width is 48ft, which would leave 11.5ft on each side for the lane that continues down to Lyndale. This isn’t insurmountable either, and I don’t think the sidewalks would need to be impacted, but it does mean that continuous bike lanes are out of the question.

    Another concern, not with construction but with winter maintenance, would be plowing the bridge. Snowplowing would easily drop snow onto the ramps and onto Lyndale.

  4. Casey September 15, 2014 at 11:06 am #

    How would people access the alley way behind Mortimer’s and the Wedge?

    • David Levinson
      David Levinson September 15, 2014 at 12:38 pm #

      As Adam notes, Alley (and maybe side street access) would be right-in, right-out.

  5. Kevin September 15, 2014 at 5:33 pm #

    I don’t think whatever minor traffic improvements this would allow would be worth it. I live two blocks from this intersection, and have crossed it twice a day for years, along with driving through it on a regular basis. It’s a busy intersection, for sure, but not too challenging to navigate by any means of transport with a bit of attention and care. Putting a bridge down Franklin would, in my opinion, only spoil the view of one of the few spots in Minneapolis where there’s actual (although slight) urban topography. It would also leave people living on the second and third floors of apartments near Lyndale looking out their front windows at passing cars, wouldn’t it? Not too nice for those people. Plus, chances are way better than good that we’d end a horrible looking overpass, not some fancy looking deluxe artist-designed one that maybe possibly theoretically could be bullt

  6. Stuart September 16, 2014 at 10:05 am #

    I think that a car bridge here would be large and unattractive. I pass through this intersection going south often because I work off 394, I live in South Minneapolis (near the 35th st exit from 35W) and passing through the bottleneck is sadly faster than waiting in line to go through the Lowry Tunnel and then merge onto 35W south. Even if this bridge improved my LOS, I don’t think that I would support it.

    What I would support is something similar, but grander for bikes and Pedestrians. I would do a X shaped bridge East to West across the valley, but I would also do a Y bridge North-South that would provide biking/pedestrian connections to either side of Lyndale up to the Existing Bike bridge at the North end of the intersection. They would connect above the existing intersection, sort of a second story pedestrian plaza

    Making this a Bike/Pedestrian bridge should make it much smaller and lighter so that it would be less offensive to look at from nearby windows. We have a better track record with attractive pedestrian bridges than we do with car bridges. It would also connect the paths on the North side of the highway tangle directly to Lyndale. That is a much needed bicycle connection.

  7. Erik September 16, 2014 at 2:47 pm #

    Neat idea but one nearly impossible problem to overcome: LHENA

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