This morning at the State of Downtown Economic Forum, the Downtown Seattle Association and Commute Seattle released an updated study of Downtown* commuting trends, with exciting results for transit advocates (our previous coverage here). Just 31% of Downtown Seattle workers now drive alone to work, a new historic low. These results continue the positive trends from prior surveys, down from an estimated 50% in 2000, 35% in 2010, and 34% in 2012.

Of course, these are proportions rather than volumes, so in a growth context a lower drive-alone rate does not necessarily mean less traffic, just as eating a proportionally smaller slice of a larger pie doesn’t mean you consumed fewer calories. Our region’s traffic woes are real and in need of attention, but nonetheless these results show that Downtown is at least keeping up with what’s needed for job growth to continue without being choked off by gridlock and unreliable transit. The results are also a ringing endorsement of the benefits of transit and density, with 45% of Downtown commuters now choosing transit, and 15% opting for non-motorized trips (walking, bicycling, or teleworking).

Within the high-level data there are also some interesting trends. The traditional Downtown core, with rivers of peak-hour transit service and the most expensive parking, has a truly impressive drive-alone rate of just 22%, whereas faster-growing neighborhoods such as South Lake Union are more than double that (46%). Clearly, transit service has not kept up with job growth in Downtown’s periphery, and this is an issue that should be urgently addressed.

Company size also appears to be a major factor, which is no surprise considering the prevalence of employer paid ORCA cards in the Seattle area. Yet interestingly, medium sized companies (20-99 employees) showed the greatest positive growth, nearly matching the achievements of the largest companies despite being exempt from regulatory requirements such as the Commute Trip Reduction law. Yet the smallest companies (1-20 employees) are still largely left out, with a relatively high drive-alone rate of 41%.

The report comes at a time when downtowns across the country are adding jobs faster than their suburbs.

* For the purposes of the DSA and Commute Seattle, “Downtown” includes everything from Elliott Bay to Broadway, and Galer to Royal Brougham. The survey didn’t include Sodo.)

Commute Seattle’s media release is below the jump: