The charts below illustrate commuting mode share changes that occurred between 2000 and 2009 (from the 2000 Census and 2009 ACS) in the 30 largest municipalities in the country. Note this data is limited to cities themselves and not metropolitan areas.
Only nine cities were able to reduce their share of 'Driving Alone' trips. Led by Boston, and followed by Seattle, Portland, Washington, and San Francisco. Texas cities seemed to encounter the greatest hurtles, with Dallas, Houston and Fort Worth in the top five for increases in driving alone trips. Baltimore and Las Vegas also saw significant increases.
In terms of other mode shares, Portland kills everybody in bicycling increases, while cities with very established transit networks (D.C., Boston, NYC) saw the greatest increases in transit use. Interestingly Detroit led off in terms of walking increases, with Boston and SF behind. Nashville saw the greatest drop in walking, while Baltimore recorded a significant transit drop.
Second, it's hard not to notice that Boston appears to be doing something right. Beside the largest reduction in driving alone trips, the city ranked in the top three for every other category including increases in walking, transit, and bicycle mode shares. Other cities that consistently ranked well included Seattle, Portland (except oddly in its transit share), Washington, D.C. and San Francisco.
(click on image to enlarge)
Jacksonville: Mode Share Changes 2000-2009 by Point Change
(One Point = 1% of All Commuting Trips)
Total Auto: -1.05
Total Non Auto: -0.48
Driving Alone: 0.34
Overall, the percentage of people commuting by automobile declined by 3.4%, and the mode share of those using non-automobile modes decreased by 2.0%. It was possible for both to decline because of an increase in people not traveling to work at all but telecommuting.
Though these numbers show little change in use for automobile and transit overall, they do provide some clue as to the effects of rail investments. When comparing cities that have no rail lines with those that have existing lines or have invested in new ones, a correlation between rail and transit use is apparent. Cities with no rail saw far smaller declines in automobile mode shares than their rail counterparts; they also saw declining non-automobile mode shares, compared to increases in the rail cities. These differences were especially considerable when considering rail cities outside of Texas; excluding them, transit saw no mode share change, whereas single-person commuting by car decreased (albeit by a minuscule amount).
This may indicate that rail lines can play an important role in encouraging the population to try modes other than the automobile. The non-automobile mode share, which includes transit, biking, and walking, is particularly interesting from this perspective because it may reflect the number of people choosing to live in areas where it is acceptable to use transportation other than the private car. Is this conclusive evidence that rail works better than bus service to encourage people out of their cars? Not necessarily, but its certainly a part of the overall equation.
Looking city-by-city, modal share changes reflect some overall trends. Automobile usage continues to decrease in the nations older, densely developed cities: The places recording the largest declines in overall car share were, in order, Washington, New York, Boston, San Francisco, Seattle, Portland, and Chicago. Those with the largest declines in non-automobile share were largely sprawling cities, including, in order, Columbus, Houston, Dallas, Fort Worth, Las Vegas, and Nashville.
Source: The Transportpolitic