Brighten Up the Bottomside of the 10

Wut, another freeway post?

We’ve talked before about the need to think about short-term improvements to freeways that strengthen the city fabric and make streets safer and more comfortable for bikes and pedestrians. That post was really geared towards everything on the surface of freeways and interchanges, but what about the area underneath freeway viaducts? There are things that could be done in the short term to improve these environments too.

Keep Houston Houston already did the legwork on this one; here’s the quick takeaway on how the undersides of viaducts and bridges should be designed:

  • Face with a solid surface. Beams and trusses create cavities that get filled with trash, guano deposits, and in some cases, affordable housing. California has an advantage here because most of our freeway bridges are continuous reinforced slabs or box girders, which already have a smooth, solid, continuous underside.
  • Paint a bright color, for obvious reasons.
  • Illuminate with bright lighting, also for obvious reasons. The lights used should be cool white LEDs, which produce a more appealing light spectrum. Traditionally, this type of outdoor lighting has been done with sodium vapor lamps, which are cheap and bright, but produce that characteristic industrial yellow glow. However, LED capital and operating costs have fallen to the point where they’re practical.
  • Bump up the level of density and activity abutting the freeway. If you want it in Jacobsian terms, a freeway viaduct is a long, skinny border vacuum. Making each side more active helps bridge the gap.

Quick Fix Bridges

For a simple case, here’s how things look today in Palms, on National underneath the 10:

What does this need? New lighting fixtures, a coat of white paint on top, and maybe some murals from local artists on the walls. This can be done quickly and for low cost. Here, enjoy an awesome MS Paint rendering of the same:


In some places, there’s already been some progress. For example, in Santa Monica, Pico was spruced up where it goes under the 10. It’s not all the way there, but it’s a start:

A Little More Work for Viaducts

I think the most interesting candidate for improvement right now is the 10 between the 110 and Olive Street. This area has already seen significant infrastructure investment in the Expo Line, and more is hopefully on the way with My Figueroa. On the north, the area bounded by the 10, the 110, 7th, and Hill is one of the hottest development markets around. To the south, USC has plans to develop new buildings, in addition to the massive Lorenzo project.

This makes the 10 viaduct a good candidate for enhancement, since it would contribute to growth in the area by making the street fabric more inviting for walking and biking. The 10 viaduct continues all the way to the river, of course, but east of Hill things are more industrial, so focusing on the stretch from the 110 to Olive will give the most bang for the buck.


Viaducts are a little harder to deal with than simple underpasses, because they create a long continuous break in the city. Often, the space underneath is used for low end uses like car or bus parking, partly because it’s not exactly a pleasant area and partly because those uses can easily be moved if you need to do maintenance.

However, it’s possible to locate more active land uses under freeway viaducts. It’s probably not a good location for apartments, but commercial, retail, and light industrial uses can work. For example, here’s some simple commercial/retail uses under the 10 between Olive and Hill:

And here’s a building (with unfortunately solid walls) under the 10 at National and Robertson:

If we look beyond LA, here’s a supermarket under the rusting hulk of the West Side Highway in Manhattan. It was always pretty busy whenever I visited:

Or try on this example near Smith-9th in Brooklyn, with a 4-track railroad viaduct going over buildings.

The key is having enough of an active city around the viaduct that it can support those retail or restaurant uses. As the corridor between LA Live and USC continues to grow, that’ll happen. I’m sure some enterprising businessperson can figure out how to turn the challenges into opportunities. For example, I’m told that exposed concrete columns are more authentic than drywall, and can be an attractive design feature in a building. Another opportunity would be to use the transverse gaps in the viaduct, say near Flower and Figueroa, to create interesting architectural features that would channel sunlight to the insides of the buildings underneath.

Maintenance Matters

Like anything, a big question is how much this will cost and who will pay for it. Caltrans probably isn’t interested in doing anything other than meeting their core mission of keeping these things in a state of good repair. The city probably isn’t interested in picking up the tab for upkeep like painting and washing either. With all the development in the area, maybe there’s an opportunity for a business improvement district to be organized to be in charge of such a project, which would increase property values in the area.

Again, it’s important to look for easy opportunities like this to make short-term improvements to the city. There’s probably more disagreement about the long-term disposition of urban freeways, but that shouldn’t stop us from doing what we can quickly to make the city a better place.


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