The northbound 405 Freeway in Costa Mesa. (KENT TREPTOW, HB Independent / March 21, 2012)

State and county agencies may know by the end of this summer how they intend to widen the 405 Freeway, which has been targeted for renovation to accommodate predicted increases in traffic.

Niall Barrett, a program manager for the Orange County Transportation Authority, said during a presentation Thursday at the Fountain Valley Mayor's Breakfast that officials are considering three alternatives to widen the freeway for 14 miles between the 605 in Seal Beach and the 73 in Costa Mesa.

A pair of draft reports, one outlining the program's engineering design and another evaluating its environmental impact, are being evaluated by Caltrans, the state's transportation agency and OCTA's partner on the 405 project. Once Caltrans finishes its review, the public will have 45 days to read and comment on the reports.

After that review period ends, the state and county groups may make their selection.

"We're hoping to get as much of a turnout and as many public comments as we possibly can," said Barrett, who listed the Costa Mesa Neighborhood Community Center, Westminster Community Center and Rush Park Auditorium in Rossmoor as probable public hearing sites.

The first alternative would add one general-purpose lane in each direction between the 605 and 73; the second, two general-purpose lanes; the third, one general-purpose lane and one express lane that commuters would pay to enter.

The alternatives would cost $1.3 billion, $1.4 billion and $1.7 billion, respectively, if created under the design-build method, in which renovations are designed and built concurrently. If Caltrans and OCTA used the traditional method, in which the renovations are designed first and built later, they would be more expensive, according to community relations officer Christina Byrne.

The expansion aims to enhance safety and allow faster travel on the 405, which dates back to the 1960s and faces a 35% to 40% increase in traffic by 2040, according to OCTA.

"It's an old stretch of freeway," Byrne said. "It's time. It's due to be modernized."

Barrett and Byrne said $600 million is earmarked for the project through Measure M, a plan approved in 1990 to improve Orange County transportation. For the remaining cost, OCTA may shift other Measure M dollars, sell bonds or use the express lane fee in the third alternative as a form of reimbursement.

Construction on the project, if approved, is expected to begin within two to five years and take about four years to complete.

michael.miller@latimes.com

Twitter: @MichaelMillerHB