Thursday, January 12, 2006

Are the declines in carpooling significant?

Use of commute alternatives continues to fall according to new State of the Region report released by Southern California Association of Governments (SCAG) released on January 5, 2006. SCAG reports that "Between 2000 and 2004, carpooling share of work trips dropped by almost 3 percent with corresponding increases in drive-alone commuting."

Using the data from the American Community Survey for 2004 for some select MSAs, it appears that LA isn't alone. However, only three other of the MSAs shown below had a statistically significant change (decrease) from 2003. Three MSAs appeared to show INCREASES in carpooling - Salt Lake City, San Diego and Tampa Bay MSAs - but those changes also are not statistically significant. An * indicates that the estimate is significantly different (at a 90% confidence level) than the estimate from the most current year. The bottom line is that communities should use care when examining these changes from one year to the next. Long term trends may be more revealing.

It would be interesting to compare changes in travel behavior based on the investments made in those options. But that's a topic for another post.

1 comment:

Tad said...

These trend lines beg several questions (and show trends that have been in place for a long time). Questions begged include:

1. Is the decline proportional to and caused by continued suburbanization?

2. What trends appear for market segments (younger, older, male, female, CBD, suburb, exurb, those with HOV lanes available, those with commute incentives available, etc.)? If these show different trends, why? If all segments show similar trends, the public policy concerning TDM is way off base.

3. What are the trends for general populations affected by gas prices, HOV lane availability, employer activity, etc.?

4. Is the mix of those who carpool changing (i.e., trends in %s of those carpooling with a family member, a friend, a co-worker, one who was formerly unknown to the carpooler, etc.)? If family and friends has grown from being 60% (rough guess with no real data in front of me) to 85% of those carpooling, it would suggest that it is becoming tougher to find others or people are becoming more wary of unknown parties. That would say a lot about how to market, how to match, etc.

5. Perhaps, the decreased funding for carpooling and related programs across the country has had some effect (although the downward trend preceded those funding cuts).

I'd like to know what others think may be contributing to this decline and whether anyone has any real information on my 5 questions.

-- Tad