There are 4,114 Intersections in LA, and He Controls Them All

Jon Bruner profiles Los Angeles Department of Transportation Engineer Edward Yu, and the ATSAC system run by Yu and his team, which controls the timing of traffic lights at each of the city's 4,114 intersections.

1 minute read

January 27, 2012, 10:00 AM PST

By Jonathan Nettler @nettsj


To judge by the level of congestion that the average driver confronts every day on the streets of Los Angeles, some might argue that Yu and ATSAC aren't doing a good enough job. But the Automated Traffic Surveillance & Control system (ATSAC), is adaptive, and as it builds a rich database of historical traffic statistics and patterns it is learning, so give it some time.

ATSAC was first implemented in 1984, the first such system in the country, and it proved itself quickly, despite what rush hour horror stories might tell you. "Repeated studies since the 1990s have found that travel times fall by 15% near connected signals and motorists make 20% to 30% fewer stops, massive improvements for a cost of about $150,000 per intersection. "

Wednesday, January 25, 2012 in Forbes

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

Close-up of "Apartment for rent" sign in red text on black background in front of blurred building

Trump Administration Could Effectively End Housing Voucher Program

Federal officials are eyeing major cuts to the Section 8 program that helps millions of low-income households pay rent.

April 21, 2025 - Housing Wire

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.

April 30, 2025 - Diana Ionescu

Ken Jennings stands in front of Snohomish County Community Transit bus.

Ken Jennings Launches Transit Web Series

The Jeopardy champ wants you to ride public transit.

April 20, 2025 - Streetsblog USA

Close-up of white panel at top of school bus with "100% electric" black text.

Driving Equity and Clean Air: California Invests in Greener School Transportation

California has awarded $500 million to fund 1,000 zero-emission school buses and chargers for educational agencies as part of its effort to reduce pollution, improve student health, and accelerate the transition to clean transportation.

5 hours ago - California Air Resources Board

Aerial view of Freeway Park cap park over I-5 interstate freeway in Seattle, Washington at night.

Congress Moves to End Reconnecting Communities and Related Grants

The House Transportation and Infrastructure Committee moved to rescind funding for the Neighborhood Equity and Access program, which funds highway removals, freeway caps, transit projects, pedestrian infrastructure, and more.

6 hours ago - Streetsblog USA

"No Thru Traffic - Open Streets Restaurants" sign in New York City during Covid-19 pandemic.

From Throughway to Public Space: Taking Back the American Street

How the Covid-19 pandemic taught us new ways to reclaim city streets from cars.

7 hours ago - Next City