Roadwork Merges at Interchange of 405, 73 Freeways

Construction on an $87.5-million widening and retooling project at the interchange of the San Diego and Corona del Mar freeways began this week in an effort to ease existing traffic snarls and ensure a smoother ride through 2020.

Much of the construction, expected to continue through 2003, is aimed at modifying access ramps at the interchange to reduce the jangle of cars exiting and entering the freeways in the same lanes.

Four lanes and a new connector road also will be built as part of the project, which will be completed in four construction phases.

“We definitely need to do something now to deal with the future,” said John Standiford, spokesman for Orange County Transportation Authority.

The interchange, which handles 280,000 cars daily, is expected to accommodate 340,000 cars by 2020.

The project is being funded mainly by the state. The Transportation Corridor Agencies, the county and the cities of Costa Mesa and Newport Beach also are paying for the improvements.

Tuesday night, workers closed the southbound Corona del Mar Freeway to re-stripe lanes in preparation for the start of construction next week on a new southbound lane from the San Diego Freeway to Birch Street. The lane, which will cost $1.5 million, should be finished in September.

In July, workers will start building a $7.3-million connector road that links the northbound Corona del Mar Freeway to the southbound Costa Mesa Freeway. Currently, drivers have to take surface streets to get from the Corona del Mar Freeway north to the southbound Costa Mesa Freeway. That phase should be completed by September 2000.

In August, work will start on a $3.9-million auxiliary lane for entering and exiting the San Diego Freeway between Harbor Boulevard and Euclid Street. To accommodate the new lane, a bridge over the Santa Ana River will be widened and ramps will be modified. Construction is expected to be completed also in September 2000.

Most of this summer’s roadwork will be done at night, but narrowed lanes and limited daytime construction will likely cause delays for motorists during rush hour.

“There will be some slowing, but when you compare it to the impact of other projects, it won’t have [much of] a traffic impact,” Standiford said. “Certainly people should think ahead, but I don’t think this will cause the same amount of traffic heartache that a lot of other projects have.”

However, the final phase of construction, scheduled to begin in December 2000, will likely cause traffic logjams, he added.

The last phase consists of $61.5 million worth of new and expanded access ramps on the San Diego Freeway and three lanes and a ramp, costing a total of $13.3 million, on the Corona del Mar Freeway.

Separating local traffic from through traffic at busy interchanges has been successful in limiting motorists from weaving in and out of shared entrance and exit lanes, said Michael McNally, a civil engineering professor at UC Irvine. Such weaving causes bottlenecks during rush hour.

“There’s still going to be congestion. There always will be. Freeways are not built to eliminate congestions. They’re built to accommodate congestion in peak hours,” he said.

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Summer Roadwork

The Orange County Transportation Authority started work this week on a road widening project at the San Diego Freeway--Corona Del Mar Freeway interchange. Construction of ramps and lanes is scheduled to be completed by late 2003. Three phases begin this summer, a fourth in December, 2000:

June ’99 to Sept.: Adding a new lane on southbound Corona del Mar Freeway from the San Diego Freeway to Birch Street. Cost: $1.5 million

July ’99 to Sept. 2000: Adding connector loop linking northbound Corona del Mar Freeway with southbound Costa Mesa Freeway. Cost: $7.3 million

Aug. ’99 to Sept 2000: Adding auxiliary lane on northbound San Diego Freeway between Harbor Boulevard and Euclid Street. Widening freeway bridge over Santa Ana River and modifying ramps for new lane. Cost: $3.9 million

December, 2000: Adding and altering access ramps mainly to San Diego Freeway and building three lanes to increase Corona del Mar Freeway capacity.

Increasing Traffic

By 2020, 60,000 more cars are expected daily on this segment of the freeway.

1998: 280,000 vehicles per day

2020: 340,000 vehicles per day

Source: Orange County Transportation Authority