Re-Thinking the Sidewalk

tree_rootsby James A. Bacon

The vast majority of sidewalks in my home town, Richmond, Va., are made of concrete slabs. Concrete materials are inexpensive and the sidewalks are easy to install. But in a burg like Richmond, where people dearly love their trees, concrete pavement presents a problem. Tree roots lift or crack the slabs, creating hazards for pedestrians. Replacement can get costly — as much as $35 per square foot in Los Angeles.

So, the race is on to re-think the humble sidewalk, reports the Atlantic City Lab. Is it practicable to use other materials? Can sidewalks be integrated into storm water management systems? Can they be used to generate energy? Is their sole function to enhance walkability?

Some locales have run underground tubes carrying hot water under sidewalks to keep them clear of snow and ice. Others are tinkering with ways to convert the kinetic energy of footsteps into electricity, which can be used as an off-grid power source. Yet others are replacing concrete with recycled, hard-rubber mats that bend and buckle under tree roots without cracking. One English university is working on a self-healing sidewalk.

Senior Land Use Planner Eric Selbst at the site of the walkable solar paneled pathway. Photo credit: GWU.
Senior Land Use Planner Eric Selbst at the site of the walkable solar paneled pathway. Photo credit: GWU.

Another cool experiment is taking place in George Washington University’s Loudoun County, Va., campus. In 2013 the university completed what it billed as the first walkable, solar-paneled pathway in the world. Under ideal conditions, the sidewalk between Exploration and Innovation halls generate enough electricity to power 450 LED pathway lights below the panels. The university hired a Spanish company, Onyx Solar, to install the solar sidewalk. The installation generated dozens of  headlines — “Walking on Sunshine” may be the best —  but the media has been remarkably uninterested in following up.

My questions: What was the cost to install such a sidewalk? How much money will it save by eliminating the need for lighting? How well have the solar panels held up? What happens when tree roots grow underneath? What are the ongoing maintenance costs?

While scientists and engineers dabble with new materials and technologies, the more important question may be to ask what sidewalks are for. Do they serve a purely utilitarian function of allowing pedestrians to get from Point A to Point B? Or should we take a broader view of sidewalks as critical elements of the public realm? Sidewalks help define the public space along a street. Wider sidewalks create space for benches, restaurant tables, planters, trash receptacles and other public furniture. A well designed sidewalk can make a place inviting, a poorly conceived sidewalk can ruin a place.

We take sidewalks utterly for granted. They deserve a lot more thought and consideration than we give them.

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14 responses to “Re-Thinking the Sidewalk”

  1. larryg Avatar

    let me guess.. not a single one of them is a private sector “for-profit” solution.. right?

    even I, Jim Bacon, realize that the most wonderful of ideas comes when the city is going to “fund” them…

    I full expect a future blog post here to raise holy heck about “million dollar” sidewalks.. right?

    let’s get your real-world private-sector, free-market solutions into this (and other city) discussions.

    you should have a rule in your blog. No posts will talk about ideas that have to be funded by the govt – only ideas that will be paid for by the free market are allowed – in other words – Conservative Smart Growth!

  2. In Fairfax County sidewalks and trails are controlled by VDOT and the County. How this is divvied up is beyond me.

    1. DJRippert Avatar

      No kidding. I run on the W & OD Trail a lot. I rediscovered running about a year ago after a long layoff. The number of people using the W&OD Trail has vastly increased since the 1990s. Far beyond population growth. However, Fairfax county & VDOT just don’t seem interested in effectively expanding the trail system in NoVa. There are endless dirt trails on public land crossing Fairfax County. But they become mud holes in the rain and they cross creeks that are unpassable in the spring, etc. A grading project, some paving and a few bridges would open up miles and miles of existing trails to the public. But it just doesn’t happen. So, you can hike the trails next to Difficult Run in solitude or run on the W&OD and feel like you are in Times Square.

      The trails are 95% there – they exist and the land is publicly owned. But for whatever reason our incompetent government can’t muster the resolve to finish the job. What a waste.

      1. larryg Avatar

        DJ – isn’t getting the govt involved in trails – “socialist”?

        Oh, and congrats on running again.. I’m right behind you but have to lose about 30 lbs… fat, ugly, old..and LEFTIST – jesus..

    2. Hokie Avatar

      Sidewalks are maintained by whoever maintains the roads in a locality. Thus in non-Arlington NOVA, they are maintained by VDOT. The W&OD however is maintained as a park by the Northern Virginia Regional Park Authority.

  3. spencer114 Avatar

    It is worth noting that Richmond has started to address the uneven sidewalk problem in a clever and inexpensive way. A few months ago the city started grinding down the protruding corners of the concrete slabs. It is my favorite development in Richmond of the last 20 years!

  4. spencer114 Avatar

    Sorry, duplicate post.

  5. Scout Avatar

    Trees and sidewalks are a difficult mix. We like both of them, but they work against each other. I am a frequent bicycle commuter from my home in Northern Virginia into Washington City. The bike trails we have are a great blessing and convenience, but there are numerous places where tree roots have undermined the trails to the point that one has to reduce speed and take care when transiting certain parts of the trail. It’s not clear (to me, at least) who has responsibility for rectifying these conditions, although it is clear that without some investment, this is not getting better.

  6. larryg Avatar

    Agree. People who “like” urban spaces tend to not like the idea of only man-built infrastructure and want the “trees” but the reality is as you point out.

    Trees in urban areas – let’s say urban areas with sidewalks – are not cost-effective .. in more modern developments – they keep the trees separate from the sidewalks.. usually.

    but down our way – recent planning rules to require sidewalks – has come a cropper as developers have challenged the extra cost for sidewalks that “don’t go anywhere” because the adjacent development has no sidewalks and the county does not plan to add them.

    but another thing the article touches on… is the world that is already beneath the streets and sidewalks.

    not only water and sewer, but stormwater, telephone, electricity, cable, internet, natural gas, etc. It’s a rat’s nest of utilities … already…

    1. Tysons Engineer Avatar
      Tysons Engineer

      Just as some context for digestion. The image shown, is a how to on not to create a streetscape. The sidewalk is too small, the planting strip is too small, and likely the section underneath the concrete was an outdated design that only promoted shallow root growth.

      Today, we 1) provide adequate vegetated space for trees by widening the planting strip. 2) Provide a sidewalk section with edging and proper aggregate base that keeps roots in the zone below the sidewalk as opposed to growing upward.

      Now that only goes so far, eventually a 80 year old oak tree may cause problems to the sidewalk, but then again most urban areas don’t propose oak trees in urban streetscapes. You are more likely to see smaller species/decorative plantings. Where there is a champion tree, special modifications would be necessary of course. Yes this costs money to retrofit poor planning and design of the past, but the point is more to incorporate good design early on.

      The same could be said about smart walkways whether they have ductways incorporated underneath so that we can save money on lifecycle on utility installation, or used for alternative benefit and value added.

      Often the public realm is the lead on these kinds of initiatives, but ultimately, in urban areas atleast, the vast majority of capital costs for walkways and interior road grids are actually paid for by private funds. If counties/jurisdictions were to incorporate proper design (whatever their goal might be) early on in these areas, it could be installed in a more logical and cost effective way without too much heart ache by developers. That being said, extraordinary circumstances like power generation etc, would have to be encouraged in some way as there would need to be a direct benefit to the builder (ie credits elsewhere like density, reductions in other requirements).

      In some circumstances (like downtown NYC, SF, or Chicago) the potential revenue may still justify even further investment like these, so you might be able to create a requirement as such in extremely expensive and high density districts, but it simply wont be the norm for 99.999% of projects in the US, atleast not at this time.

  7. larryg Avatar

    and of course – for those with Libertarian inclinations – take note – 98% of sidewalks and trails don’t exist if not for government eminent domain.

    1. Tysons Engineer Avatar
      Tysons Engineer

      As noted above, while govts maintain systems (in urban areas atleast) they are not typically the ones that fund it. When they do, its usually funding that comes from special proffers or urban tax districts levied on new development or the district as a whole (see Tysons).

      That being said, the maintenance is just as important as the genesis, and I think the GOP/libertarians do have massive problems with their argument that “private business built that” the retort to Obama’s statement from years ago. No in fact, without the govt acting as a pooler of funds (at local, at state, and at federal levels) we’d all be driving on a non-network of disconnected private roads with tolls that end before the location you actually intended to go. The govt acts as 1 part financier 1 part master coordinator, otherwise the whole thing goes to shite.

  8. larryg Avatar

    rubber sidewalks made from recycled tires – sounds like a win-win… with a little twist of irony!

    and they are porous!

  9. shaunalex Avatar

    Thanks for the article, I like the idea of sidewalks and of re-thinking sidewalks. In Fairfax, new subdivisions with sidewalks are accepted into VDOT’s inventory (whether the state wants it or not). If there are sidewalks on both sides of the street, VDOT gets one side and Fairfax gets the other. If sidewalk only one side, it can go either way, though often falls on the state/commonwealth

    As mentioned, the W O&D is a NVRPA property. Fairfax Park Authority also maintains the Cross County Trail (CCT), which is both paved and unpaved. And as mentioned, there are miles of natural surface stream valley trails that many people want to keep natural. I see commuters and walkers all over all of these trails. Wet and cold feet won’t kill any one.

    If not for evil governments, none of these would exist. A great example of private sector trail/sidewalk building is when my Grand Dogwood Elite Estates community trail ends 500′ before your Hill Valley Shopping View Manor community trail begins.

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