Obviously, I do rockets, so I like things that fly. This is not some inherent bias against flying things, but there is a challenge with flying cars in that they’ll be quite noisy, the wind force generated will be very high. Let’s just say that if something’s flying over your head, a whole bunch of flying cars going all over the place, that is not an anxiety-reducing situation.

~ Elon Musk

Fictional boy inventor Tom Swift (later the father of boy inventor Tom Swift Jr.) invents a powerful explosive that helps to dig a big tunnel through a mountain in pre-WWI Peru, discovering the lost Incan city of Pelone. From the sewers of Paris to the Lincoln Tunnel in Manhattan, we have been fascinated by finding and creating subterranean passages.

Roads grid our towns and cities to make all places accessible to automobile traffic, sometimes at the expense of pedestrians. In places like Oklahoma, rural roads follow section lines, the square-mile grids that surveyors use to catalog the land, providing access to all corners of the country.

But access brings traffic and all its attendant problems — noise, congestion, foul air — and serves as a social barrier, separating places and communities, as well as connectors. The freeway boom of the ’60’s and ’70’s, designed to facilitate regional and national movement of automobiles, isolated communities, often underserved minority enclaves, exacerbating their conditions.

We use stop signs, traffic lights and roundabouts to manage the intersections. Bridges span roadways and pass over valleys and rivers to smooth the flow of traffic and facilitate development, while tunnels pass below the obstructions. Railroads, light rail and canals provide the same barriers to traffic and can be addressed through the same measures.

Recently, regional traffic planners have investigated high-speed trains to supplant local light rail and subways. Elon Musk of Tesla fame has proposed regional underground ‘hyperloop’ systems that travel at high speeds and local underground ‘3D’ systems that supplant surface traffic grids. He notes, “We’re trying to dig a hole under LA, and this is to create the beginning of what will hopefully be a 3D network of tunnels to alleviate congestion. So right now, one of the most soul-destroying things is traffic. It affects people in every part of the world. It takes away so much of your life. It’s horrible. It’s particularly horrible in LA.” He notes that the key to both concepts is the development of new tunneling technologies that increase the efficiency of tunneling machines by a factor of 14 (almost as good as Tom Swift).

Another approach puts the roadway below ground, but not in an actual tunnel. The road is cut down below grade, and then capped. The capped surface becomes available for use by surface traffic and, more frequently, as public space. These ‘cap parks’ or ‘deck parks’ are often spurred by development in the urban core and can provide green spaces in otherwise over-developed areas.

The most popular place to put a city park is, increasingly, on a highway.

~ Martha T. Moore

The extent and design of these spaces varies and may include local roads, bike paths, pedestrian plazas, street art and natural settings. Some may be barely wider than a two-lane bridge, while others may cover large areas and intersect with adjacent parks or developments.

Some critics consider these parks an attempt to greenwash highway expansion projects. “Highways aren’t a very nice place to be,” notes Angie Schmidt, Editor of Streetsblog USA (quoted in Moore). I suppose the argument is that these solutions are only band-aids that ignore or facilitate the root problem — automobile traffic. However, proposed solutions (electric cars, mass transit, alternative fuels, and others) to automobile traffic problems (noise, dirty air, congestion, and others) would complement deck parks anyway. If we’re going to build transportation corridors, we might as well make them as green as we can.

Someday, I envision a laser machine that bores through the earth, melting the rock and soil to form an inner crust, capturing the fumes for separation and recovery of the metals, and creating a smooth tunnel for whatever transportation mechanism is needed at the time.

If Elon Musk isn’t up to it, maybe Tom Swift III will appear and do it for us.

Additional information:

Victor Appleton, Tom Swift and His Big Tunnel, 1916, Grosset & Dunlap

Martha T. Moore, Where to Build a Park? The Denver Post, April 3, 2018

Elon Musk, The Future We’re Building – and Boring, April 2017, TEDTalks