Can pedestrians and elevated highways coexist?

So here’s Roppongi:

Obviously very few of us can achieve the urban intensity of a city like Tokyo, but still, here’s what is by all intents and purposes a vibrant and pedestrian-friendly retail district which exists directly underneath an elevated expressway. Since we US Americans have a lot of elevated freeways, since removal often isn’t practical and since trenching can be cost-prohibitive, it’s worth asking – What’s different?

The underside is solid, painted white, and lit.

This is huge. Standard North American freeway architecture has individual beams with dark, shadowy voids in between. These beams are typically unpainted, and left to weather with age to become a dark brown color. This suggests the underside of the freeway as a shadowy realm. Who knows what could be lurking under there?

For instance, at one point WashDOT found a homeless shanty that had been erected on the underside of Seattle’s 520 bridge. The kid had sunk metal spikes into a column, bridged the flanges of two beams with plywood, and tapped into the street lighting electrical system. There was a mini fridge and a playstation in there! This kinda thing doesn’t happen with the steel box that roughly half of the Shuto network is constructed with.

With a solid, well-lit underside, the freeway simply becomes the ceiling of the street “room,” a logical extension of the “street wall” concept into the vertical plane.

Pedestrian attractors are on both sides of the structure

Another big one. Many of the US’s elevated freeways skirt waterfronts or other areas where the freeway separates a fringe area from the whole of the city. In this context it’s very easy to cut off the fringe area. This is one of the big differences between SF’s (now dead) Embarcadero Freeway and Seattle’s (soon to die) Alaskan Way Viaduct. In SF the buildings on the waterfront were sparsely spaced and even today many are reserved for industrial and maritime uses. Whereas in Seattle the waterfront was long a tourist attraction, with a high density of attractions. Hence there’s always a decent amount of foot traffic on Alaskan Way (the surface street) even though it’s 50 feet from a double-deck expressway.

The underside of the structure is open, with good sight lines

This is pretty much the opposite of standard US practice. 1960’s planning literature repeatedly emphasizes parking as a preferred use for under-freeway space. But a bunch of parked cars reinforce the status of the under-freeway space as a shadowy warren. Think how many action movies rely on shootouts in parking garages – Jason Statham crouching behind an SUV, watching for the baddie’s legs to move – and you see the issue.

Now the question that naturally arises is,

What about the Pierce Elevated?

It’s not going anywhere. And it’s probably not getting trenched anytime soon. How can we make it more… walkable?

The City has already done a decent job of making it more attractive from the street side by planting closely-spaced street trees and erecting wrought iron fences. This creates a sort of street wall at the edge of the freeway and defines the edge of the street instead of letting it filter out into some vague, shadowy and undefined realm.

Most of the Pierce’s bents have four or five columns, so there’s really not a lot you can do to make it open and airy underneath. In the long term you could probably build out some retail space down there, but as a cheap solution the iron fence works.

What you’re left with then is the beams and the lighting situation. One of the substantial pedestrian flows under the Pierce Elevated is from the Inbound bus stop on Louisiana at Travis three blocks east to the Downtown Transit Center. Presently the point where you get off the bus has NO overhead lighting of any kind. This is really not the way it should be.

Houston’s concrete is naturally substantially lighter than most other cities, by virtue of climate and geology. So I’m not sure the white paint is even really necessary here. But installing decent lighting mounted to the underside of the structure, and leaving it on 24/7, would make a huge difference. Do it with LEDs and the electricity cost becomes almost negligible.

11 thoughts on “Can pedestrians and elevated highways coexist?”

  1. Do you think it is better to have the elevated section over a road like in your picture, or over lots as with the Pearce elevated. With the Pearce there is essentially three block lengths of dead space N to S.

  2. That’s… a really good question.

    Elsewhere in Houston you have the Elysian Viaduct which does the “zero ROW acquisition” thing and goes directly over the local streets. I always liked that area, feels kind of cyberpunk. But “emulate Gibson novels” is generally not considered a development best practice.

    I think on the one hand it’s better to have some amount of open street space. Pierce itself seems like a more inviting pedestrian environment than Roppongi-dori, since it’s always bathed in sunlight. But on the other hand if you give the highway its own land it takes longer to cross and fragments the neighborhood more. You can make it across Roppongi-dori in 130′, Pierce and the area under the elevated are together about 200′, but once you start adding ramps and whatnot you end up with something like 75 through Dallas which entails almost a quarter-mile walk between the nearest sidewalk-engaging building faces.

  3. Noise is first thing that comes to my mind. The Pierce is like the Atchafalaya bridge! If they were to re-do the ’97 rebuild, perhaps some modernizing is in order along the lines of repaving with a more flexible mix, fewer columns, and more perfectly level. The only other below-freeway experience in Houston nearly as walker friendly would be the 610/Westheimer overpass; there’s balls to punish drunk drivers! Great blog for a 2016er.

  4. I’ve thought about this in the context of the 10 and the 110 in Downtown LA. In general, the CalTrans commitment to monolithic poured concrete with a smooth bottom (as opposed to your typical beams and deck seen in most states) would lend itself easily to some nice lighting, murals, etc.

    With the opening of the Expo Line, USC’s expansion plans, and the Figueroa Street plan, development is naturally starting to fill in the corridor between downtown and USC. The 10 is on a long, badass viaduct that forms the only real barrier to this development. You can see a couple of blocks between 17th and 18th where they’ve built some low-grade commercial development under the freeway.

    Regarding awp’s question, I like the setup of the 10 where it runs between 17th and 18th, or for that matter, the Pierce Elevated. You could develop the space between the viaduct and the surface street, screening the viaduct from view except at cross streets. OTOH, CalTrans might want that space as a staging area if they ever rebuild the thing, and might not be so crazy about the idea of losing that space. The “zero ROW” thing creates an entire street that is a total sketchfest at night, especially if you’re not a dude.

  5. Also, if you go onto the Elysian Viaduct in Street View, when you get up to around Lyons Ave, there’s a horse on the right. Okay, Houston, I’m officially impressed with the no zoning thing.

  6. The way I see it, it’s not the elevated freeways themselves, so much as the on and off ramps, that cause an area to thrive or decay.

    Houston and Dallas make great contrasts for this. The freeways encircling downtown Dallas have ramps that take a lot of potential real estate out of commission, sometimes in the form of circles (cloverleaves). Whereas in Houston, the downtown freeways tend not to have ramps at all. In both cases, you get blight/underdevelopment.

    The presence of a freeway in a populated area can attract development, or scare it off. People, by default, don’t like to be situated right next to a freeway, because of the noise and (depending on the freeway’s size and whether or not each side runs perfectly parallel to each other or wobbles around) the way they disconnect places/street networks. People will only willingly set up shop next to one if they can feed off the traffic of it. And people will only willingly *live* next to one if enough people have set up shop there to make the place a vibrant corridor with plenty of things to do.

    Without ramps, the urban fabric that freeways run through has no way to feed off their traffic because people driving on them can’t exit to go to a place they see. So entrance and exit ramps are needed, but they can’t be built in a way that uses up too much valuable land. They have to be short and compact. The on and off ramps should be grouped in pairs, parallel to each other, and perpendicular to the freeway itself.

    But wouldn’t that force drivers to drastically slow down before exiting and make it impossible for those entering to do so at a high speed thereby slowing the overall traffic of the highway down below American highway norms? Yes, it would. In order to make the area around free flowing highways pedestrian friendly, you have to discard the notion that traffic speeds on them must always be at least 60 mph. In an urban context, highways/freeways/tollways, need to yield to the urban fabric, not the other way around.

  7. The thing about the “short ramps and low speed limits” thing is that we already have a testbed for this mode of design, it’s called the east coast. For instance, 83 into Baltimore is posted 50. But off-peak traffic runs about 65ish, and many go faster – when you get thrown into the hard right-hander at Mount Royal the barrier is black from all the skids. The Schuylkill and the Vine Street in Philly, same dealio. East River Drive is 40 but I have personally been passed on the right while doing about 70-ish (granted, this was late at night).

    So basically your urban freeway is going to run 65-70 regardless, you might as use appropriate design standards. Really the Houston “loading and unloading platforms” ramp configuration is pretty genius. I don’t think Pierce Street suffers from a lack of car traffic, it could just stand to be a bit more ped-friendly.

  8. The main problem with making a pedestrian space under an elevated freeway is the that freeways spew toxic micro-particulates into the immediate area (with radii up to 1,000′). This dust has long been known to have deadly long term health effects. Maybe as your above pictured example shows the white “ceiling” could actually be a fur-down ceiling to incorporate the mechanical systems necessary to buffer noise, clean/circulate/pressurize the air, and provide lighting. That same ceiling system could also cantilever a shading device out a few feet over the sidewalk; it gets hot.

    FYI: I used to rent a parking space under the Pierce Elevated for $50.00/month and I could never keep it clean b/c of the freeway dust.

  9. That Danish setup ain’t bad at all. And the freeway is low-rise, too, similar to the Pierce. The under-freeway air scrubber is an interesting concept, but I doubt there’s room for it on the Pierce. Certainly if you built retail underneath I’d expect them to have their own central air conditioning and filtration systems. Might just have to change the filters more.

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