Route Types Geometry: Terms that fit a Square Grid better?

For the maps in the post Route Types: Geometry I purposely chose a city map without a repetitive square grid. I wanted to draw different route types on an irregular street network to show the geometry types would also work there (if they make sense is a different matter). Such irregular street networks are common throughout the world but are an exception in cities which have been recently founded. Most cities in the new world chose a Hippodamian plan for their street layout.

For an overview of American grids varieties,  of Discovering Urbanism put together a nerdy planning-related poster, which I adore.

Variety of American Grids

I wanted a nerdy planning-related poster for my wall, so I made one this week. I scoured Google Earth and measured that quintessentially American grid in about fifty downtowns around the country. Of course, there are variations in block proportions within downtowns, but I tried to pick cities that had more uniformity than average to come up with a single prototype.

Quote from  Variety of American Grids.

Route Types: Geometry tries to describe route types in an abstract irregular city and is not written from the perspective a resident of  Houston or Barcelona. Terms to describe geometry e.g. radius, diameter or tangent might not come to mind if your are use to a square street grid. There are several duplicate names to describe the same type of route geometry in different parts of the world and also within other language. One effort to give names consistently to route geometries was by Jarret Walker and in his book Human Transit, Chapter 4 he discusses this. Jarret defined I-shaped and C-shaped routes as the basic shapes, and which then can be connected to form L-shaped or S-shaped line. That sounds logical. A L-shaped route would for example run 8 street blocks southwards and then make 90° turn and take a 4 block path east. A S-shaped route would run west, 90° turn, then south, 90° turn, then east, followed by a 90° turn, then south ending with a 90° turn and a west route. All easily mapped out on a square street grid, and if the letters are displayed with seven segment display characters they really do look the same. What would the equivalent from the previous post be?


Letter Character Seven Segment Character Equivalent
I radial, secantial, direct
C tangential
U arcantial
L  tangential
S   maeander
O   circular, circumferential


Further Reading:

Alon Levy discusses in the post C-Shaped Lines reasons why cities might build C-shaped lines.


Post image by Fgrammen/Fanis Grammenos

Hippodamus of Miletus was an ancient Greek architect, urban planner, physician, mathematician, meteorologist and philosopher, who is considered to be “the father of European urban planning”.



  1. I’d love to see business plans as routes. When that business serves a nascent population, its statistics start out hyperbolic, become Euclidean, and become spherical as many competitors chase the same population via different routes. The underlying geometry matures. The paths move from one fragile path to one solid path, to many solid paths.


  2. Where is the ubiquitous T-bone intersection? They arise when two separate settlements crash into each other. Then you have railway right of ways, rivers, mountains, bridges, and tunnels dominating routes.


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