Urban Scaffolding: 6 transport technologies which will be largely removed in coming decades
Elements of Access: Transport Planning for Engineers, Transport Engineering for Planners. By David M. Levinson, Wes Marshall, Kay Axhausen.
Like buildings under construction, cities are built with scaffolding. Remove the scaffolding and cities remain. Yet what is "scaffolding" and what is "permanent" is not at all clear. Yesterday's permanent structure is today's scaffolding.
Take for instance the deployment of streetcars in the late 1800s and early 1900s. These streetcars enabled (not coincidentally) suburbs from which their customers, resident travelers, would use on a regular basis to commute to jobs and journey to shops. Yet in the mid-20th century these streetcars (urban scaffolding if you will) were removed (just as horsecars before them), and the city itself remained. Those streetcar suburbs still exist sans streetcars. That which enabled their construction and occupancy was eventually unnecessary and removed.
Ports were the reason d'etre for many cities, yet in today's era of containerization, ports that failed to make the transition for whatever reason withered. The city that port enabled remains. These include such places like the City of San Francisco, New York City, and London, which today lack significant port operations, yet have maintained or gained in status. The port scaffolding was removed, and the rest of the city was self-sufficient without. However in the absence of an initial port, those cities may never have been more than hamlets.
The scaffolding enables the construction of an urban web of social, economic, and technological elements that eventually becomes thick and secure enough that the initial framework can disappear without taking the system down with it. But at the time, no one envisioned the port or streetcar as temporary. They seemed permanent.
So what today seems permanent but is simply the scaffolding for tomorrow's city?
If I were to offer speculations ...
Start with the at grade (or elevated) urban interstate. Without the urban interstate, today's cities would look much different. Many would argue better, but no one would dispute different. It is not that there will be no surface passenger transport goods movement, but that it will look very different in 50 years (30 years) than it does today. For freight, we will be in a world with self-driving delivery vehicles and aerial drones. Through traffic could always avoid the central city, to traffic can be carried on surface streets as needed. Vehicles are considered a nuisance if they are seen and heard, even with pollution levels down to almost zero and vehicles much safer. Roads which carry those vehicles enable the nuisance. These roads will be bridged over (land for driverless (and especially passengerless) vehicles is too valuable to expose it to the sky), or rebuilt as high capacity tunnels under the city. Construction of course is costly (and disruptive), but with advances in tunneling technology, further automation, and the right economic model, this will be justified in larger areas.
Move on to traffic lights. Without traffic lights, we never would have managed to maintain the urban auto-mobility we do have, it was critical scaffolding for the twentieth century auto-dominated city. In tomorrow's world, they will preserved in selected districts only for their historic authenticity, not as actual control devices. Traffic will continue to need to be controlled in places, but that control can be conducted invisibly through radio spectrum, rather than with colored lights designed for the human driver's eyes. The difficulty will be dealing with pedestrians in mixed, congested environments (if it's not congested, pedestrians will just have right-of-way, if it's not mixed, there isn't a problem). More discrete in-ground sensors will detect and guide pedestrians across busy intersections. Most downtowns will be largely pedestrianized, so these locations will be at the edge of the core.
We will probably kill off most of the remaining mass transit in all but the largest cities. Large lumbering vehicles showing up every 10, 20, or 60 minutes provide a poor level of service compared with the equally if not more cost-effective shared single passenger AV, which will be nearly on-demand and will be point-to-point. Only the highest frequency routes serving the most passengers (think urban subways or the El) will remain.
We will certainly kill off the remaining gas stations with the transition to electric vehicles. While trucks may switch to LNG for a period, cars will move to EV status rapidly over the next two decades. EVs powered by renewables will be cheaper than gasoline-fueled cars even with low gas prices. The gas station sites will be converted, as many already have been to shops and convenience stores. Other auto-related uses, like dealerships and service stations, will also become scarcer and scarcer. Land is too pricey in the central city for these to be visible, especially when cars can get themselves serviced, or drive out to you for a test drive, or are shared in the first place.
We will eliminate most urban parking lots and garages, both because cars can drive farther away to park, and because shared vehicles can be in motion for much more of the day. Again space is too valuable.
We will eliminate most larger cars and passenger trucks. People will be able to get the larger vehicles on-demand, which turns out to be not that often for most people, and will use the right size car for the trip. While most vehicle forms will remain in the population, the share of single person vehicles will grow enormously, and the larger vehicles will shrink as people choose to save money once they realize the opportunity cost of not having the large vehicle for the occasionally.
It's not that cities will be unrecognizable, it's just that the parts of the cities we like will become more and more prominent, and the parts we hate will tend to shrink in size. Plenty of twentieth century changes (skyscrapers, skyways) will remain part of the landscape, and the huge expansion seen by the twentieth century will largely remain in place so long as urban populations continue to grow.