I aggregated these reports by the residential density of the household s zone. Residential density is the number of households in the zone divided by the number of residential acres and is an excellent measure of the neighborhoods we live in. While another zone containing only housing could appear to have a higher density but really be much more sprawled out and less inviting to pedestrians, bicycles and transit use. Or a dense urban zone which includes a handy commercial and office area and local parks would also have unrepresentatively low population or households per total area. These results parallel the studies of driving, transit use and walking trips among European cities.
Denser cities have less driving per capita.
Transit trips per capita increase with density until they reache a maximum at moderate densities and fall or remain constant at higher densities. Walking continues rising as density increases. And this makes sense. When density increases driving falls as trip lengths are shortened and more can be taken by transit or walked or bicycled. Transit trips increase with density until trip distances become short enough that more are taken by bicycle and foot.