Building Up

The High Line (New York City)
Source: NYC Dep. of Park & Recreation

Soaring real estate prices in the San Francisco Bay Area have got me thinking about density and urban planning. In particular, I have been wondering whether there is a better way to use all the space currently dedicated to roads and highways.

San Francisco Presidio Parkway (Under construction)
Source: SFCTA

The San Francisco Presidio Parkway is being redesigned as a park over an existing roadway that is being placed within new tunnels. San Francisco selected James Corner as the lead designer for the Presidio Parkway. Corner is an architect known for his work on The High Line, an elevated public park in New York. I love the idea of creating public parks above existing road infrastructure. Both drivers and pedestrians benefit from such separation, and new space is created in constrained area.

San Antonio River Walk - Below Grade
Source: Wikimedia Commons

While public parks above roads are a new creation, there are numerous examples where communities have separated automobile traffic and pedestrians through multi-level design. It sure is nice walking below grade around downtown San Antonio's River Walk and not encountering vehicles. Las Vegas has taken an alternate approach and sent their pedestrian traffic on walkways over the Strip.

Las Vegas Pedestrian Bridge - Above Grade
Source: Louis Berger

In addition to pedestrians, animals benefit from being separated from traffic. Banff National Park in Alberta is famous for its multiple wildlife crossings, which connect bifurcated ecological regions and reduce roadkill. More pictures of wildlife crossings are available at theworldgeography. An organization called Animal Road Crossings (ARC) is working to create new wildlife crossing structures. ARC hosted a design competition for wildlife crossing infrastructure in 2011, and hopes to spread new ideas on this topic.

Wildlife Crossing in Banff, Alberta
Source: Parks Canada

In some cases, building structures have been built above roadways as well. This wikipedia list catalogs dozens of structures built over roadways. One such structure that always struck me as odd is the Crowne Plaza in Newton, MA just outside of Boston. The Crowne Plaza sits directly above the Massachusetts Turnpike, and its reviews include numerous complaints from guests about highway noise that keeps them up at night. A hotel is probably not a good choice directly above an open highway, but the Crowne Plaza provides an example of the range of possibilities for building above roads.  If the turnpike had first been placed in a tunnel, then covered with a park, the Crowne Plaza location might be quiet and pleasant for guests.

I can imagine a future of covered roads, creating spaces for new parks, walking trails, wildlife crossings, and buildings depending on the pre-existing surrounding environment. Such structures would increase urban density, and hopefully avoid sprawl. I look forward to following the advances of ARC and others working to create low cost, multi-use, above road crossing structures so that we can build up our roads to support more than just cars.

Crowne Plaza Newton, MA
Source: Google Street View