American taxpayers have spent trillions of dollars building freeways since the passage of the National Interstate and Defense Highways Act of 1956. This network of freeways has re-shaped American cities, and arguably impacted the economy and culture of the country. While some enthusiasts find interest in the highway system’s endless strips of asphalt, for most the only true drama within the system is contained in freeway interchanges, where one or more freeways intersect. Although designed by traffic engineers, interchanges can contain dramatic ramps and intriguing shapes from above. One artist even took inspiration from the world’s freeway interchanges to design a set of tiles featuring their shapes.
Of these highways, Washington, D.C.’s Capital Beltway is among the more famous, as a symbolic dividing line between the national capital and the rest of the country. Let’s take a look at some of the interchanges in and around the beltway, to see what they reveal. We will approach the city from the north on Maryland’s I-270. Here, that highway branches in two as we approach the beltway.
If we travel East on the beltway we come across this interchange near College Park where I-95 intersects the beltway. Original plans for Washington’s freeway system included an extensive network of urban freeways that were never built — this interchange was designed to accommodate a never-built leg of I-95 extending to the District. Today, University of Maryland officials are advocating a freeway connecting this interchange to their campus.
As we continue along the beltway we come to this recently rebuilt interchange between the Capital Beltway and Route 50 in Prince George’s County. This photo shows the close relationship between Washington’s freeway and Metrorail system. From the very beginning the systems were designed somewhat in tandem and the train was intended to carry visitors into the city after arriving this far by auto. Here, special onramps connect the beltway to the New Carrollton Metro Station.
Continuing around the beltway we encounter the Springfield Interchange, one of several interchanges around the country known popularly as “The Mixing Bowl.” Here the beltway intersects both I-395 and I-95, and the interchange was long one of the most dangerous stretches of the beltway. In 1999, the Virginia Department of Transportation began an 8-year project to re-design the interchange in a project that is currently estimated to cost in excess of $670 million before it is complete.
As we continue around we come to the last I’ve selected for inclusion — this interchange where the beltway meets Route 50/Arlington Boulevard.
Interestingly, perhaps because of the investment in Metro, the scale and number of the freeway interchanges in the region is not notable from a national perspective. This image of the Big Dig in Boston gives a good idea of the scope of that project.
Unlike Washington, the city of Detroit did actually construct the entire network of urban freeways planned for that city, including some truly massive interchanges like this one, between I-96 and the Southfield Freeway.
Much more is written about interchange design and the Washington region’s freeways elsewhere on the web, so I won’t go into detail here. What am I missing? What is your favorite (or least favorite) interchange in the region?
> Scott M. Kozel’s Roads to the Future (Transportation history for VA, MD, DC)
> Kurumi’s Field Guide to Interchanges
> Springfield Interchange Improvement Project
> Google Earth Community: Crazy Highway Interchanges thread