Most downtowns will expand, but when does a downtown get too big?
What is the value in a large downtown? It isn't just about workers commuting to a single location in a metro area with as many people as possible from every direction. In a bigger downtown, your business can recruit, train, and retain workers with the most-wide range of talents for your city's cocktail of specialized workers and the many other workers who support them.
Central business districts in most cities are referred to as downtowns. In New York City, the real downtown is Midtown. London’s downtown is called City Centre. Downtown Chicago is often called the Loop and San Francisco’s downtown the Financial District.
These districts all have one thing in common—they represent special spaces in which workers can commute from each direction of their metro areas in similar proportions across these downtowns.
Downtowns seem capable of squeezing five to ten minutes of commuters’ time on the freeway or train before commuters from one part of the metro area become impatient. Downtowns cannot just keep stretching. The range of a downtown is cut short. Market demand for office space fizzles.
In a major downtown, stop-and-go trains and rush hour freeways can move commuters—at best—at twenty-five miles per hour. If you double the speed of a freeway at rush hour, it should almost double the downtown’s physical size.
How else will autonomous traffic increase the size of downtowns?
First, double the speed of your freeways and you double their reach—in every direction—which increases your metro area’s size exponentially. It also increases the demands on the role your central business district is supposed to play.
Second, most American downtowns currently anchor to one side of a freeway, but autonomous traffic will increase traffic volume and push commuters to both sides, doubling the downtown footprint.
Third, with autonomous traffic, most downtowns will be able to utilize not just one freeway, but a pair of intersecting freeways, and those downtowns will be able to increase their size even further.
Finally, by add free-flowing exits with their own rights-of-way, the scope of your downtown can be flagship ambitious.