A proposal to extend the Orange Freeway to the San Diego Freeway along the Santa Ana River bed has no apparent technical problems but would cost at least $810 million, a study completed this week shows.
An additional $40 million could be added to the cost because of sophisticated interchanges that might be required to alleviate traffic congestion on surrounding streets, according to the preliminary review conducted by Deloitte Haskins & Sells for the Orange County Transportation Commission.
The study looked at three alternatives for extending the six-lane freeway 10.5 miles from its present terminus near the Garden Grove and Santa Ana freeways:
Constructing northbound and southbound lanes at ground level on either side of the river.
Slightly elevating the lanes on either side of the river.
Constructing the entire freeway on the east side of the river as an elevated structure up to 40 feet high.
The first alternative would face the problems of potential flooding from the river and the effects of noise on residents near the river, the study said. Wall sound barriers would cost about $1 million a mile, according to the report.
Elevated structures also would pose problems. Caltrans has estimated their cost at $70 per square foot. Additionally, higher overpasses across the freeway would require the acquisition of more right of way on either side of the river, the study said.
However, the study said, some savings would be available by coordinating the freeway extension with construction of a planned $1.1-billion flood protection plan on the river, although the extent of those savings cannot be known until more detailed studies are done.
Staff members of the Army Corps of Engineers, which is designing the flood control plan now before Congress, "believed that, given adequate time and financial resources, the projects could be made compatible," the study said.
Transportation officials say additional study will be needed before the Transportation Commission can decide how to proceed with the proposal.