By Chris Smith and Randy Miller

Portland's approach to land use and transportation planning for the past 40 years has been about creating affordable, accessible choice and ensuring that cars are not the only option for getting around. Portlanders have been clear in their support for this approach, and the Metro travel behavior survey data shows this is working; vehicle miles traveled (VMT) have declined by 26 percent per household since 1994.

While the region has experienced a 4 percent decline in auto trips, the central city has seen an 18 percent decline in car trips and inner neighborhood trips have dropped by 13 percent. We need to continue our efforts to provide the rest of Portland the same quality and variety of options as the central city.

Why?

First, this is an issue of equity. Cars are expensive to own, insure, maintain and drive. Not all Portlanders can afford to own, much less drive, a car. A strategy focused solely on autos marginalizes the most vulnerable people in our community.

Second, our multimodal strategy provides economic benefits. Portland drivers spend about $700 million each year on gasoline alone, and those funds contribute little to the local economy. As economist Joe Cortright has explained, declining VMT results in a "green dividend" for the city and the region; money that would otherwise be sent out of state and overseas to oil companies stays in the local economy, supporting local businesses. And the "millennials" -- the generation that will provide our next cohort of well-educated entrepreneurs -- show a marked preference for smartphone ownership over auto ownership as they migrate to central city areas.

Third, it's more cost-effective. Portland's bicycle transportation investments have allowed the key bridges into the city's downtown to operate as well for automobiles today as they did 20 years ago, despite an increase in population and economic activity. Between 1990 and 2008, the number of crossings on these four bridges increased by 12 percent. Bicyclists accounted for the entire increase, as the number of cars crossing those bridges has remained constant since 1990.

Fourth, the future vibrancy of our central city depends on it. The reality is there just isn't the room or the funding to accommodate more cars, especially in the central city. We cannot afford to expand our freeways, streets and parking garages to accommodate future growth in the heart of Portland. The Central City 2035 Plan is about moving more people -- not vehicles -- in an effort to create a more vibrant city center with jobs, housing, recreation, educational institutions and cultural events for all residents, workers and visitors.

Let's be clear, though: Portland and the region are not neglecting automobiles. From 1995 to 2010, the region spent $4.2 billion on roadway improvements, while spending $2.3 billion on other modes. And the city of Portland has been active in supporting the changing role of cars by promoting car-sharing programs and electric vehicles.

Cars -- in whatever their future form may be -- are here to stay. But so are bikes, transit and walking. Through thoughtful planning, we can accommodate all modes of transportation, while increasing human and environmental health.

Chris Smith is a member of the Portland Planning and Sustainability Commission. Randy Miller is president of Produce Row Property Management in Portland's central city.