Bridge project explained at open house
About 25 residents and city officials attended a recent open house to discuss plans for the seismic retrofit of the North Torrey Pines Bridge.
“The restoration project will protect this historic resource we have of this coastal, concrete classic bridge,” Public Works Director David Scherer said in his presentation at the Sept. 14 City Council meeting.
He joined Interim City Planning Director Brian Mooney and representatives from the companies hired to analyze and plan the project in answering questions at the gathering at City Hall Annex on Sept. 10.
The California Office of Historic Preservation has determined the bridge, which connects Del Mar to Torrey Pines State Beach, is eligible for the national register of historic structures. Work will be done in stages and is expected to begin sometime in summer 2010 and take 2 1/2 years to complete.
“Except for the nighttime closures the bridge will be open in both directions,” Scherer said. He estimates 10 to 12 nighttime closures.
“The project will restore the complete look of the bridge,” Scherer said. He gave the historic Cabrillo Bridge at Balboa Park on Highway 163, which recently underwent a similar project, as an example.
The southbound lane during construction will be a “share the road” lane for bikes and cars because the bikes are going faster on that side, while a four-foot-wide northbound bike lane will be available.
The bulk of the funding for the project comes from the Federal Highway Administration. The remainder will be covered by the state with Proposition 1B matching funds, Scherer said.
The plans have been in the works for years, with the city of Del Mar paying 20 percent of the design costs, amounting to about $4.8 million total.
“We’ve spent three years studying the need for a new bridge,” Scherer said. He said the “new” bridge wouldn’t be entirely new.
The “substructure,” which consists of the vertical columns and support structure below the deck, will not be removed, he said. Instead, it will be “renovated, strengthened and seismically protected.”
The “superstructure,” on the other hand, will be entirely replaced. The deck, median and railing will all be recreated to match the original design – down to the board form pattern, stamps, stucco details and plaques.
The only difference, Scherer said, is that the gaps in the railing will be narrower. He explained that the cost to get a totally new rail design approved would be significant. Instead they’re going with a design used for a similar Texas bridge that had already been through the rigorous process.
A mitigation plan for the sensitive plant and animal species in the Los Peñasquitos Lagoon was recently approved. It addresses rare species that can be found in the area including the coastal California gnatcatcher, the Belding’s Savannah sparrow, the Mexican free-tailed bat, the American peregrine falcon, the white-tailed kite and the pocketed free-tailed bat.
The Mexican free-tailed bat uses the underside of the bridge’s superstructure to roost between the months of March and November.
Devices to keep the bats off the bridge during construction will be installed prior to Feb. 1. Alternative habitats, or large bat houses, will be constructed nearby and treated with the bat’s guano.
Sensitive plant species identified in the vicinity of the project include the sea dahlia, southwestern spiny rush Coulter’s goldfields, California box-thorn and the torrey pine. The only plant growing within the construction limits is the spiny rush.
Animal experts from the U.S. Fish and Wildlife Service will survey the area, train construction workers, oversee installation of anti-erosion fences, monitor the work and surrounding habitat for damage and noise levels, and provide direction throughout the process to ensure minimal environmental damage and disruption.
A re-vegetation and restoration plan will be finalized prior to construction and the impacted area will be monitored for five years following completion of the bridge project.
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