The Human Transit website discussed both concepts earlier this year and noted that beyond mobility – a measure of one’s ability to move through a community efficiently – access is the measure of what your mobility is meant to accomplish.
Jarrett Walker uses an example of a resident who wants to shop at a grocery store 3 miles from home and can do so relatively quickly because transit provides mobility to the store although the trip itself may take 5 miles due to the bus route's configuration. What the shopper really wants is access to that favored store. Having it right next door would be preferable to having it 3 miles away or even 5 miles by bus.
A community requires good mobility to avoid wasting time in traffic congestion, and transit-oriented development (TOD) improves access, Honolulu rail’s third goal: “Improve access to planned development to support City policy to develop a second urban center.” Walker writes:
Dropping in on the Human Transit site regularly could be a habit that improves both one’s understanding of transit in general and the Honolulu rail project itself.