A city staff report stated that the intersection operates at 81% to 91% capacity during the morning rush hour and 71% to 80% capacity in the evenings.
It forecasts that the intersection will exceed its traffic-capacity limit by 2030 if the city does not act soon to alleviate the bottleneck.
"The traffic growth is expected," Huntington Beach Transportation Manager Bob Stachelski said. "We're trying to get out ahead of that and plan a project that's going to take several years to try and implement, to try to at least keep conditions about what they are today over the long haul."
Mayor Matthew Harper said congestion at the Brookhurst-Adams intersection has not eased since he was traveling the area to get to Orange Coast College about 20 years ago. He added that more times than not, traffic on westbound Adams backs up to the bridge.
"There's so few alternatives to be able to cross the Santa Ana River," he said. "There's no Garfield-Gisler bridge. People aren't going all the way around further south."
Residents and city planning commissioners argued that there is no need to widen the streets.
The project was originally denied by the Planning Commission on Nov. 12, but Mayor Pro Tem Joe Shaw appealed the decision for council review.
"We felt that the intersection could adequately handle the current and future traffic needs and that expanding it would probably bring more traffic at the intersection to and from Costa Mesa," Planning Commission Vice Chairman Erik Peterson said.
Several residents in Huntington Bay, near Adams and Piccadilly Lane, said they have difficulty merging onto Adams and believe the project would make it worse.
"As a resident of Huntington Bay since 1987, I can state that traffic patterns on Adams Avenue have not changed significantly in the last 27 years," resident Paul Haussler said.