Thinking Outside the Lines: CNT and King County Metro Develop Pioneering Residential Parking Calculator

RSP logoKing County Metro Transit, the public transportation administration agency for King County, Washington (which includes Seattle), recently released the Right Size Parking Calculator website, an innovative new tool that allows users to view estimated parking use in the context of a specific site for multi-family developments. The calculator was developed in collaboration with CNT, with grant support from the Federal Highway Administration’s Value Pricing Program.

The announcement came at a ULI Northwest luncheon headlined by Donald Shoup, who discussed the art and science of parking.

King County was interested in developing a tool that could be used to achieve a more balanced approach to parking for the region. Outdated parking requirements have led to parking supply that is not reflective of actual demand, which can have a direct impact on a jurisdiction’s ability to create compact, healthy communities.

The calculator can help analysts, planners, developers, and community members weigh factors that will affect parking use at multi-family housing sites. It will help them consider how much parking is “just enough” when making economic, regulatory, and community decisions about development.

RSP Screenshot

“As with much of CNT’s location efficiency work, we have again found that urban form—access to jobs, concentrations of people, and regional transit access—explains travel demand,” said Scott Bernstein, CNT’s president. “Past studies have shown this to be true for auto ownership and use, so it makes sense that where urban form factors are strong, the need to provide parking spaces is reduced.”

The calculator’s estimates are based on a powerful model developed from current local data of actual parking use collected in field work on more than 200 developments in urban and suburban localities in the County. These parking use data were correlated with factors related to the building, its occupants, and its surroundings—particularly transit, parking pricing, and population and job concentrations—to build the model.

Preliminary findings of this research were recently published in the ITE Journal.

King County Multi-Family Residential Parking Calculator:

Right Size Parking Project website:

For more information, please contact Daniel Rowe at King County Metro Transit.