Has Seattle Solved the Science of Parking Demand?

Parking regulations are generally formulated as uniform standards that apply to hundreds or thousands of parcels equally, often resulting in overbuilt supply. But what if planners could anticipate the parking demand down to the parcel?

1 minute read

April 27, 2013, 5:00 AM PDT

By Jonathan Nettler @nettsj


As Emily Badger reports, Seattle's King County Metro Transit agency, with the help of the Center for Neighborhood Technology and the Urban Land Institute Northwest, have been working on solving the parking supply vs. demand conundrum and may have achieved a significant breakthrough.

"They've spent the past year trying to measure exactly which factors dictate residential parking demand around the region, in downtown Seattle, in urban neighborhoods, in the suburbs and even farther out. The result of their efforts is this Right Size Parking Calculator web application that can estimate parking demand down to a single parcel of land (and that should be replicated in other cities)," she writes.

"The idea is that developers might use the tool when planning a project," she adds, "but also that local governments might consider this data in updating their parking regulations. King Country is agnostic about what they come up with."

"The name 'Right Size' is very conscious because we don’t want to just say 'in all cases there should be less parking,'" says Ron Posthuma, the assistant director of the King County Department of Transportation. "In some cases, maybe there should be more."


Friday, April 26, 2013 in The Atlantic Cities

Young Professional

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban and Environmental Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban and Environmental Planner

Get top-rated, practical training for planners

"Planetizen federal action tracker" logo superimposed over black and white image of US Capitol dome.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

September 23, 2026 - Zachary Whalen

Passengers board an Amtrak train under a cloudy sky.

Amtrak, CN end decades-long dispute with eight-year agreement

The new operating agreement establishes an updated framework for the companies to work together, including processes to resolve disputes.

September 18, 2026 - Mass Transit

An Airo train driving towards the camera on a track. There is a forest behind it.

Northwest rail fans eager for Sept. 30 debut of Amtrak’s Airo fleet

Get ready for that new train smell and more seats. But they won’t go faster or run more frequently on the Cascades route in Washington and Oregon.

September 22, 2026 - Washington State Standard

The outside of a brightline transit hub with many windows on a sunny day.

Brightline Florida files for bankruptcy

The transit company is over $5 billion in debt.

5 hours ago - Financial Times

A blue Metrolink train with two cars drives toward the camera.

St. Louis Metro to test if single-car trains can reduce operating costs, maintain rider satisfaction

The pilot program will run from October to spring 2027, and begin with one single-car train operating on Metrolink’s Red and Blue lines.

September 25 - Mass Transit

An abandoned mine in Pennsylvania. The ceiling is low, the walls and floors are gray, and mine cart tracks run along the bottom.

Pennsylvania is building data centers in abandoned mines

Housing data centers in mines provides an alternative to destroying local forests and may spare residents from data centers’ noise and air pollution.

September 25 - Inside Climate News

FREE Course: Walkable City 1: Why Walkability?

After describing his path towards focusing on walkability as the essence of good planning, Jeff Speck marches through his five principal reasons for making more walkable places.

Reinventing Malls: Planning Alchemy—Turning Gray Fields Into Gold

The course focuses on the opportunities and imperatives that shape reinvention of mall sites.

Senior Planner

City of Thousand Oaks

Community Development Director

City of Wisconsin Rapids

Professor of Urban Planning

Harvard University Graduate School of Design