I am rather helpless at estimating the actual size(s) or distance(s) of many things, but every once in a while I'll peer across traffic and find myself sort of amazed at the amount of actual physical land necessary to support major roads and large intersections. This observation is focused less on the negative effects of traffic or mechanics of driving, but is rather my very unscientific method of taking mental measurements of urban space.
Freeways and expressways - limited access highways that carry auto and truck traffic - are roadway types that commonly claim significant amounts of urban space. They can be placed below-grade (i.e. uncovered in a trench or covered in a tunnel), at-grade with the adjoining uses (but with access nearly always limited by barriers), or above-grade as elevated-type roadways. Their primary purpose — to provide continuous routes between the types of places humans desire to reach and inhabit — often puts them in contact with, but separated from, other nearby land uses.
Examples of below-grade, at-grade, and above-grade freeways
Freeways are complementary to urban development (i.e. by increasing access to city areas and movement across a region) but they have an (often earned) reputation of impacting surrounding areas. Putting aside the negative effects of congestion / pollution, the limited access nature of freeways significantly (and in some regards, ironically) restricts local movement and the large sunken infrastructure investments (and high costs of construction/land acquisition) make them particularly difficult to re-engineer and improve.
If the amount of available land in metropolitan areas continues to diminish/become more valuable, freeways may provide some opportunities to create "new space" for development and community places.
Urban freeways are often located nearby - and create the edges of - desirable areas in cities (driven in some part by the access provided by the freeway). They offer sizable and contiguous plots of undeveloped space with ownership often held in trust by some level of government (as opposed to privately-owned land).
Each of these factors, in addition to the community-based benefits of reconnecting separated land uses (e.g. by covering below-grade roadways with platforms and creating larger usable areas than simple traffic bridges), make them appealing for development. Some of the challenges of building above urban freeways seem to include higher construction costs, the political reality/feasibility of building above roadways, and the overall engineering / design demands.
In some communities building "on top of" or underneath freeways may be more desirable and/or appropriate than other approaches, such as freeway removal (examples would include San Francisco's Embarcadero Freeway, Portland's U.S. Highway 99/Harbor Drive, and Milwaukee's Park East Freeway), actual relocation of expressways (such as with the Big Dig in Boston), or and of course, the status quo.
This post is not really intended to advocate for a particular method of addressing freeways in urban areas (a complex and costly endeavor that is particular to each locality). Rather, its purpose is to simply provide some examples of projects and community spaces that have been built in unique ways to incorporate new development over, nearby, and above existing highway infrastructure.
Over the next several days I'll add some photographs from around town of examples of building on top / below existing freeways:
- Buildings and community spaces built above the Franklin D. Roosevelt East River Drive
- Residential partments and bus terminal above the Trans-Manhattan Expressway / Cross Bronx Expressway / approach to the George Washington Bridge
An aside… My first experience with a highway deck (with the specific purpose of creating additional urban space) was the Freeway Park in Seattle. The Freeway Park is built over Interstate 5 and I remember feeling quite enlivened knowing that I was hanging out above the Interstate highway. The contrast was impressive to me - a sort of "civic conquering" of the space above the traffic below.
Is my understanding correct that the Big Dig will create similar types of spaces (parkland built above the buried freeway)?
Filed under Community Planning, Transit and Transportation with 3 Comments
|3 Responses to “Buildings Located On Top Of (and Underneath) Freeways, Expressways, and Highways”
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January 11th, 2008 at 4:31 pm
yes, the big dig is now completely park land above where the interstate runs. Boston also had an older experience with decking, as the Prudential Center is on top of the masspike. There is currently work going on to deck further areas of the highway, however (at least as I understand it without any engineering training) there is a lot of difference between decking (like Prudential) and a tunnel like the big dig.
ps. check out the most recent post on bldgblog. As a parking lot fan, you'll enjoy it.
January 15th, 2008 at 11:38 pm
Thank you for the update on the big dig. That is interesting information - to understand that building above roadways will continue in the area (through decking).
I'm not an engineer either so I attempted to take a cautious approach to the topic - I imagine there are a number of difficulties in actual placing an inhabited building over an active roadway highway (e.g. support systems, access to the roadway, ventilation, etc).
As I began to really look at highways I noticed that many have portions located below-grade (i.e. sunken in trenches). These types of roads may be prospective candidates for decking (sort of the "dig and cover" model of building on top of infrastructure). Retrofitting existing roadways may be a means to "bridging the gaps" that sunken roadways often create.
You are probably familiar with the I-94 trench through the metro area of Minneapolis and St. Paul (circumventing downtown Minneapolis on the southern and western-sides). I remember hearing a number of ideas about decking over portions of this freeway (one that I liked the best - building a large deck along the Nicollet Avenue bridge and to create space for a downtown grocery store or other commercial uses) to create connections between the downtown commercial district and communities to the south/Eat Street.
Tunneling - where actual digging takes place below the surface (my very simple definition of tunneling entails keeping the surface level, above the tunnel, in tact) does seem to be much more complicated.
February 24th, 2008 at 10:46 pm
Several weeks ago the daily newspaper AMPM featured Sutton Place in its City Living section. Parts of Sutton Place (primarily open space areas) are constructed over the FDR Drive (photographs)