Transportation and the 30 minute rule

Travel times, Cities, and Subcities

Transportation speed determines the size of the social city. The urbanized metro area can have multiple submetro urbanities, (which I will call Subcities. These are determined by 30 minute accessibility by car from a reference point (and can overlap). Maximizing travel speed reduces the number of subcities within an urbanized area. This means building freeways reduces sprawl because it increases the incentive for jobs to stay in the core. Houston’s freeway expansion, and tollway building has resulted in a much more compact city than other areas of similar age and region. For example Atlanta only has The Perimeter or IH 285. While Houston has IH 610, and SH Beltway 8/Sam Houston Tollway (which is a county tollway), as complete loops; and SH-99 as a partial bypass. This means that you can go from outer suburb to outer suburb without going on Loop IH 610 in Houston. While in Atlanta you have to go on the Perimeter or IH 285, to go from outer suburb to outer suburb. The fact that Houston is built as a block along her beltways rather than a squid stretching out along her radial freeways, enables her to have the highest percentage of jobs in the core municipality. And she also has the second most jobs of any municipality in the US.

Opportunity Zone Comparison

30 Minute Opportunity zones on the left, and Hour Opportunity Zones on the right

By car the Houston Galleria subcity has more people than Midtown Manhattan by Subway under the 30 minute rule. This means that employers in the Houston Galleria Area have more available employees within 30 minutes, which is most peoples commute tolerance (which means more happy employees, that are more willing to put in the hours). It is not until you get to an hour that you get a larger subcity. But as Houston grows into a megacity in the coming decades Houston will have the larger hour subcity radius. Larger opportunity zones (or subcities), especially of the 30 minute variety lead to more economic progress. For the wealth of a city is largely a function of it’s size and importance. Which means that the larger the opportunity zone is for a city and the more unified the city is the richer the city is all other things being equal.

Houston is the richest city in the world under RPP GDP per capita. This is because Houston controls the worlds highest paying industry: Energy. And it maintains that dominance through good transportation, and a talented workforce.