Five Years After $1 Billion Freeway Expansion, Traffic Only Gets Worse

The lesson of the I-405 widening project that birthed meme-worthy events like "Carmageddon": widening a freeway won't reduce congestion for long, if ever.

1 minute read

May 8, 2019, 8:00 AM PDT

By James Brasuell @CasualBrasuell


Interstate 405

An unusually light traffic day on the 405, as viewed from Sherman Oaks in the San Fernando Valley. | trekandshoot / Shutterstock

Five years after the completion of a northbound carpool lane on Interstate 405 in Los Angeles, built at a cost of $1 billion, traffic has only gotten worse.

"Since then, average northbound drive times through the Sepulveda Pass have increased at all hours of the day," reports Elijah Chiland, citing data from traffic analyst Inrix.

The project has delivered poor results in terms of congestion mitigation since it opened, so this latest news is only the most recent bad news for drivers who travel the Sepulveda Pass between the San Fernando Valley and the Westside of Los Angeles. The Los Angeles County Metropolitan Transportation Authority promised a 37 percent reduction in overall hours of delay with the project as compared to a scenario that never built the project.

But broken promises and congestion are probably the least of the concerns associated with the freeway widening project. "A 2015 policy brief from the National Center for Sustainable Transportation notes that expanding freeways is likely to result in a long-term increase in both greenhouse gas emissions and the number of miles driven in a given area," according to Chiland.

Monday, May 6, 2019 in Curbed Los Angeles

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

Get top-rated, practical training

High-rise apartment buildings in Waikiki, Hawaii with steep green mountains in background.

Study: Maui’s Plan to Convert Vacation Rentals to Long-Term Housing Could Cause Nearly $1 Billion Economic Loss

The plan would reduce visitor accommodation by 25,% resulting in 1,900 jobs lost.

April 6, 2025 - Honolulu Civil Beat

Wastewater pouring out from a pipe.

Alabama: Trump Terminates Settlements for Black Communities Harmed By Raw Sewage

Trump deemed the landmark civil rights agreement “illegal DEI and environmental justice policy.”

April 13, 2025 - Inside Climate News

Two yellow and white Dallas Area Rapid Transit light rail streetcars at station in Dallas, Texas.

North Texas Transit Leaders Tout Benefits of TOD for Growing Region

At a summit focused on transit-oriented development, policymakers discussed how North Texas’ expanded light rail system can serve as a tool for economic growth.

April 3, 2025 - KERA News

Sprawling housing development in suburban Summerlin near Las Vegas, Nevada.

Nevada Bills Aim to Establish Home Insurance Assurance Amidst Wildfire Risk

Republican sponsor hopes the FAIR plan would be “a true market of last resort.”

45 minutes ago - Nevada Current

Small red car driving on forested road passing "Welcome to Virginia" sign.

Virginia Law Allows Judges to Mandate Speed Limiters

The law could set a new precedent for speed limiting tech on U.S. vehicles.

1 hour ago - Streetsblog USA

Colorful sunset view over Chattahoochee River in Georgia.

Comment: EPA Cuts will Send Atlanta Back to Eye-burning Ozone, Lung-damaging Smog, and Raw Sewage in the Chattahoochee River

A veteran political journalist takes stock of the hard-earned ground Georgia stands to lose with slashed environmental protection.

2 hours ago - Georgia Recorder