Here to There: Transportation Planning in a Climate-Neutral City

Big transportation projects can contribute to sprawl and increase automobile use—or, they can promote biking, walking, and use of transit. Seattle is working to take the latter path.
Seattle 520, by K David Clark

Sunset on the SR 520, pre-construction. Photo by K David Clark.

Seattle hopes to become the world's first climate-neutral city. It's no small task: The City must account for, and reduce, the carbon footprint of everything from transportation to trash for hundreds of thousands of people. City Council President and YES! Magazine board member Richard Conlin is blogging about the city's efforts.

One of the most formidable challenges in climate policy is to design a transportation system that minimizes the consumption of carbon. That challenge is compounded when regional and state leaders are the final arbiters of major capital-intensive transportation projects, and the city’s role is simply to influence and guide rather than make the final decision.

Many people—especially those concerned about embedded carbon in construction projects—have an understandable, visceral reaction to large transportation projects. Any big project begins with a strike against it, because opponents to large-scale construction projects prefer to promote “travel conservation.”

Small projects that encourage walking and bicycling are the most obviously carbon positive. But they're often not enough. In our society, travel patterns and needs are complicated, and some big projects not only make sense, but are essential to our lives and to commerce. Three principles should guide project evaluations:

  1. We must dramatically reduce the use of fossil-fueled vehicles. Fossil fuels are not only getting more and more expensive, they're also major contributors to emissions that cause climate change. Recent events in the Gulf of Mexico underline other adverse impacts of the life cycle of fossil fuels, and at some point these resources will run out.
  2. The best long-range strategy is to create compact urban communities that are attractive to people and businesses. We know that population and economic activity will grow. New development should link housing and jobs by transit, bike, and pedestrian facilities. It must also be livable and desirable—public safety, schools, and parks are climate-positive essentials.
  3. We must reduce vehicle miles per capita; but we must plan for vehicle movement, especially to link the jobs and housing in urban centers. Vehicles will still be in use, and will need extensive road structures. The Zero Carbon Britain 2030 project, for example, achieves zero net emissions by reducing personal trips by car from the current 80 percent share to 54 percent, electrifying all private vehicles by using renewable resources, and employing hydrogen and biofuels for heavy vehicles that require liquid hydrocarbons.

Core strategies for major transportation investments that reduce carbon emissions should be to:

  • ensure mobility through and between major job and housing centers;
  • emphasize transit and bicycle/pedestrian connections; and
  • provide efficient vehicle capacity but avoid capacity increases.  

These strategies have guided Seattle’s work on major transportation projects. We have made extraordinary strides over the last ten years in ensuring that regional projects move in the right direction. Projects have been scaled to give priority to transit and bicycle/pedestrian access, and to make these aspects integral to project design. Here’s an overview of Seattle’s four big projects and how they measure up:

  1. University Link Light Rail, connecting downtown to the University of Washington, and then north into Snohomish County. This system serves major centers along a 10-mile corridor, with future development opportunities using high-capacity transit.
  2. Rebuilding SR 520 between I-5 and I-405. This bridge across Lake Washington creates a critical second connection between urban areas on the east and west sides; the new design adds no capacity for single occupancy vehicles, but it supports transit with lanes for buses and high-occupancy vehicles. A bicycle/pedestrian path is included on the bridge, and it has been designed to be ready for the addition of a future light rail. The Westside interchange design also will alleviate traffic for Seattle transit heading north-south. (The original proposal was for an eight-lane highway; city officials and legislators deserve credit for backing away from that plan).
  3. Eastside Link Light Rail connecting Seattle across Lake Washington to Bellevue and Redmond. A light rail connection will be a critical transit corridor for the west and east side urban areas.
  4. Replacing the Alaskan Way Aerial Viaduct through downtown Seattle with a Bored Tunnel. Removing the aerial road system would allow for new bicycle/pedestrian facilities on the waterfront and new parks on the waterfront and downtown. The system would reduce vehicle lanes from six to four and would promote downtown transit by removing traffic from downtown streets. [Notes:  Costs are not conclusively known until contracts are signed; entries and exits to the tunnel must be integrated into urban design; transit components are not yet funded; tolling must be designed to manage impacts on downtown streets.]

Common Ground Book In Review: Common Ground in a Liquid City

Re-imagining our cities is the best chance we have to create prosperity, lower our carbon emissions, and save what’s left of the natural world.

Seattle’s representatives have worked successfully with the region and state to make these projects fit into the urban environment and to bring elements supporting transit, bicyclists, and pedestrians to the forefront. None of the projects increase the capacity for single occupancy vehicles, and all are consistent with a strategy for reducing vehicle miles traveled per capita. They provide transportation choices for people and freight between urban centers and help to implement a successful growth management strategy. Project benefits are likely to be greater than the costs in embedded carbon, especially as the new infrastructure should last between 50 and 100 years.

Ten years ago, Sound Transit was on the ropes, beleaguered in its attempts to complete its first light rail line. The 520 bridge was projected to double in size—from four to eight lanes, with no dedicated capacity for transit. The aerial viaduct was going to continue to be a safety risk and blight to Seattle’s waterfront. All that has changed—for the better.

Seattle’s own investments in bicycle and pedestrian facilities and usable streets have contributed to a better city environment. Our contribution to the regional dialogue has moved this area into a transportation strategy that works and a carbon reduction strategy for the future. Big transportation projects can contribute to sprawl and increase automobile use.  Thanks to our successful partnerships, these big projects are moving in the right direction instead.


  • from Richard Conlin's blog about Seattle's quest for climate neutrality.
  • : The Americas have lagged behind Europe in promoting bicycle transportation, but recent government efforts may change that.
  • : Orion Kriegman finds life without a car the opposite of onerous.
  • : How do we get around? Post-carbon travel starts with walking, biking, more public transit, less commuting, more local buying.
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