The Orange County Transportation Authority officially broke ground on its nearly $2-billion 405 Freeway construction project on Friday.
The construction is expected to last until 2023, at which point the freeway will have one more regular lane heading in each direction between Highway 73 in Costa Mesa and the 605 Freeway in the Seal Beach area, officials said.
A second lane will also be added to the existing carpool lanes on that 16-mile stretch to create new express lanes that motorists can pay to use for a quicker commute. Carpool drivers will still be able to use the lanes for free.
Officials say the move is a response to mounting travel times on the freeway, a major artery through Orange County. While a rush-hour commute from Costa Mesa to the Los Angeles County line currently takes about an hour, after the widening it will only take about 30 minutes, according to OCTA.
In the express lanes, the trip could take as little as 15 minutes — the same amount of time it takes with free-flowing traffic — officials said.
Though ground was broken Friday, motorists won't see many visible signs of construction until spring, and commuters' travel times likely won't be impacted until summer, OCTA spokesman Joel Zlotnik told Voice of O.C.
OCTA currently does not have an official construction schedule but it expects lanes will be open during the day and closed between 10 p.m. and 5 a.m. Significant congestion during the day is not expected as a result of the construction, officials told KTLA.
An interactive map is available to help drivers track construction and find detours.
While the Orange County Transportation Authority says it is the busiest stretch of highway in the nation, it's unclear if that's true.
The most recent study by the U.S. Department of Transportation found the 5 Freeway in California was the nation's busiest, followed by the 10 and 110 freeway, based on data from 2011. The section of the 405 Freeway that runs through Los Angeles was deemed to be the busiest interstate in any American city.
In 2015, the American Highway Users Alliance released a list of America's biggest bottlenecks that put the 405 Freeway between Highway 22 and the 605 Freeway in Long Beach at No. 2. The group is a nonprofit that advocates increased funding for highway construction projects.
OCTA says the $1.9 billion project is being bankrolled through a combination of local, state and federal funds and was approved by voters as part of Measure M, Orange County’s half-cent sales tax for transportation investment.