City Driving Efficiency


I was thinking about the variations in city street styles. Some have very regular grid structure when they have been planned but haphazard street structure is more common in old cities which evolved organically over time.

I have built a JavaScript project which takes a city and by plotting a random set of journeys via walking or by car, one can see the relationship between the two to see the effect of one-way streets and how cars are directed off the most direct route because they must follow one-way streets etc.

Each city produces an efficiency score, which relates to the one-way streets effect. Ie if a city has no one-way streets, then the walking routes and car routes would be very similar (giving a score near 1); but a city with many one-way streets or awkward routing schemes will have a higher score.

Comparing driving versus walking
Simulating lots of journeys Simulating lots of journeys
Comparing the distances for driving versus walking Results
Results for cities

How it was done:

I created a web-application in Javascript which utilises the Google Maps Directions service. It takes a GPS location for the center of a candidate city and a radius for which to operate. For the specified number of journeys, a random selection of start and end points are chosen randomly within the specified radius (cogniscent of the non-linearity of GPS units versus metres). For each of these journeys, 3 distances are noted. The direct line-of-sight distance, the distance to walk it as per google maps and the distance to drive it. Using this, a ratio figure is constructed to reflect the extra distance a car must travel (due to one-way streets etc) compared to a simple walk.

This ratio thus reveals an aspect of each city, with respect to how efficient its street organisation is.

- Posted December 2015.