Traffic Down 30% in Cities: How?

New data show that in 2008 traffic congestion in the nation's cities declined by 30 percent, the result not of new roads or transit, but of modest declines in VMT.

1 minute read

March 6, 2009, 8:00 AM PST

By Tim Halbur


The decline in congestion -- which analysts have labeled 'startling" -- was almost universal. Traffic congestion actually declined in 99 of the nation's 100 largest metro areas, according to Inrix, which monitors traffic around the nation. The company's data come from tens of billions of reports from GPS-equipped vehicles traveling the nation's roads, the same data that provides real-time traffic information to commercial users and web-services like Mapquest, Garmin and On-Star.

Their key conclusions: 'peak hour congestion on the major roads in urban America decreased nearly 30 percent in 2008 versus 2007,' and nationally, 'congestion was lower every hour of every day in 2008 versus 2007 – between 15 percent and 60 percent lower depending on the hour and day.' See the full report here.

How did such a small decline in travel produce such a big drop in congestion?"

Tuesday, March 3, 2009 in CEOs For Cities

portrait of professional woman

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 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 Planner

Use Code 25for25 at checkout for 25% off an annual plan!

Interior of Place Versailles mall in Montreal, Canada.

Montreal Mall to Become 6,000 Housing Units

Place Versailles will be transformed into a mixed-use complex over the next 25 years.

May 22, 2025 - CBC

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

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

7 hours ago - Diana Ionescu

White and yellow DART light rail train in Dallas, Texas with brick building in background.

DARTSpace Platform Streamlines Dallas TOD Application Process

The Dallas transit agency hopes a shorter permitting timeline will boost transit-oriented development around rail stations.

May 28, 2025 - Mass Transit

Line of multi-colored big rig trucks drivign down highway with other traffic including a yellow school bus.

Study: 4% of Truckers Lack a Valid Commercial License

Over 56% of inspected trucks had other violations.

June 4 - FreightWaves

Pedestrian holding visual impairment cane pressing crosswalk button.

Chicago Judge Orders Thousands of Accessible Ped Signals

Only 3% of the city's crossing signals are currently accessible to blind pedestrians.

June 4 - DRA Legal

People on bike wearing helmets stopped at intersection waiting for passing cars in Philadelphia, Pennsylvania.

Philadelphia Swaps Car Lanes for Bikeways in Unanimous Vote

The project will transform one of the handful of streets responsible for 80% of the city’s major crashes.

June 4 - Philly Voice

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Planning for Universal Design

Learn the tools for implementing Universal Design in planning regulations.