[jyl]

In 1994 the local transit agency surveyed Portland residents to determine travel patterns, and they did it again in 2011. I have no idea why they don’t survey more often than once every two decades, but anyway I thought the results were interesting.

Basically, there has been a significant shift in travel patterns away from cars and toward transit and bikes – in the very central area of the city. For the region as a whole, there has been some shift for “commuting trips” and a smaller shift for “all trips” (this is everything: grocery shopping, soccer games, kids to school, errands, visiting friends, etc).

None of this is terribly surprising, but the magnitudes (large or small) are interesting. Basically, it looks like these shifts mean about 200K/day fewer car trips overall and 82K/day fewer car commuters, for the Portland region.

For downtown, it means about 23K/day few car trips and 6K/day fewer car commuters. What is the context? Is this significant?

Downtown Portland has about 10K street parking spaces, about 4K city-owned parking garage spaces, and (I estimate) probably about 3X that number of private garage spaces, for a total of maybe 25K parking spaces. 6K / 25K = 24%. Pretty darn significant.

Our bridges across the Willamette carry very roughly 360K vehicles/day (Burnside Bridge carries 58K/day cars, Morrison Bridge 54K, Hawthorne Bridge 26K, Ross Island Bridge 55K, Fremont Bridge 110K, and I’m missing one bridge). I’d think about half of trips to/from downtown have to cross a bridge – twice, coming and going. So 23K * 0.5 * 2 / 360K = 6%. Fairly significant.

So I think the shifts are quite significant for the central city. By the time you get to the neighboring counties, or the further part of the suburbs, I think the shifts are not significant. The in-between is, well, in-between.

[Summary of data]

Numbers are rounded, so may not sum to 100%
Number in parentheses, like “(30K)”, is number of trips/day

Trips to/from the central business district (downtown):

All trips
1994 all trips – 56% by car, 14% by transit, 27% walk, 2% bike
2011 all trips – 46% by car (130K), 21% by transit (60K), 27% walk, 6% bike

Commuting only
1994 – 58% by car, 34% by transit, 6% walk, 2% bike
2011 – 44% by car (30K), 45% by transit (30K), 4% walk, 8% bike

Trips in entire Portland metropolitan region including suburbs:

All trips
1994 – 87% by car, 3% by transit, 9% walk, 1% bike
2011 – 84% by car (5.7MM), 4% by transit (290K), 9% walk (630K), 3% bike (190K)

Commuting only
1994 – 90% by car, 6% by transit , 3% walk, 1% bike
2011 – 81% by car (820K), 11% by transit (110K), 4% walk (40K), 5% bike (50K)

Use of transit, walk, bike is heavily correlated to whether you live in the central city, and also to terrain (flat vs hilly)

Live in central business district
1994 16% transit 40% walk 2% bike
2011 16% transit 47% walk 3% bike

Live in central city
1994 10% transit 36% walk 3% bike
2011 22% transit 23% walk 13% bike

Live in eastern outskirts of city (flat)
1994 6% transit 12% walk 2% bike
2011 6% transit 16% walk 8% bike

Live in western outskirts of city (hilly)
1994 3% transit 15% walk 1% bike
2011 6% transit 11% walk 2% bike

Live in suburbs, still in county
1994 2% transit 6% walk 1% bike
2011 4% transit 8% walk 2% bike

Live in neighboring county
1994 1% transit 7% walk 1% bike
2011 1% transit 5% walk 1% bike

Use of transit is heavily correlated to household income

2011 <$25K 9% use transit, $25-75K 4%, >$75K 2%

People are driving fewer miles in shorter trips

Miles/driver/day 1994 21 miles 2011 17 miles
Average trip 1994 5.1 miles 2011 4.4 miles
The avg household makes 9.2 trips/day, goes up w/ household size, basically each person makes about 3 trips/day