July 21, 2000


Market Creek Plaza Trolley Bridge Project Sets Engineering Precedent

The successful installation of a bridge for the San Diego Trolley tracks near the new Market Creek Plaza commercial development set a safe, cost-and time-effective precedent, while minimizing service disruption for trolley riders.

A 60-foot bridge was set in place near the Euclid Avenue trolley station to allow excavation and construction of an entrance way into Market Creek Plaza from Market Street. The bridge's innovative construction approach was simple, yet accomplished an otherwise very complicated process in a short period of time. In only 22 hours, 400 feet of trolley track and wooden ties were removed, the bridge deck —comprised of six, 100,000-pound, pre-cast, post-stressed concrete panels— was set in place, and the tracks replaced. Also unique is the excavation beneath the bridge, usually one of the first steps in the process, was last, as the driveway beneath the bridge will be dug out over the next two to four weeks. This will cause no further service interruption.

The usual construction process, consisting of removing one track, building half of the bridge beneath it, then doing the same for the other track would have caused a four-to-five month disruption in service. However, the unusual engineering solution proposed by Simon Wong Engineering allowed the preliminary work, which began in April, to be conducted with no impact on trolley service.

"The construction work was outstanding," said Jim Hammett, Market Creek Plaza project manager with the Jacobs Center for NonProfit Innovation. "By taking this approach, we saved $400,000 and placed a minimal strain on residents in the area who need the trolley for transportation. While the power was off, we bused riders between the Euclid and 47th Street station, and they were all very supportive of our efforts."

The Metropolitan Transit Development Board (MTDB), which oversees capital improvements made to the San Diego Trolley, also was supportive.

"This is definitely an approach that can be adapted and used in similar projects in the future," said MTDB Associate Systems Engineer Chip Finch. "I think the success of the project was a result of the thorough planning by the Jacobs Center, the designers and the contracting firm."

Initially expected to take 14 hours, the project was slightly delayed by the removal of old, wooden ties under the track and adjustment of one of the rails, requiring extra time for cutting and welding. Also, MTDB requested 280 additional feet of track, more than doubling the original 120 feet. MTDB provided much of the materials, including rail, for the project.

John Weldon, project manager for Herzog Contracting Corporation, was in charge of the Market Creek Plaza trolley project for his firm.

"MTDB has been very supportive of our ideas, and they were willing to give us all weekend to finish the installation," he said. "We were able to do it in half that time, thanks to good teamwork, which is a credit to the Jacobs Center's foresight. An additional benefit derived from this ideas was eliminating the intermingling of traffic and rail, which can be very dangerous."

Added MTDB's Chip Finch: "This project has a lot of support from MTDB's management largely because of what the Jacobs Center is trying to do for the community. It is not our practice to use a method never before proven or tested. But this was an excellent project, and with some creativity, the planners came up with a solution that would prevent service interruption and still provide high quality construction."

Keith Gazaway was one of the structural design engineers working on the project for his firm, Simon Wong Engineering.

"We came up with the idea while brainstorming with some of our engineers and contractors," Gazaway said. "The concept is unique, in that it did not require a large underpass be built. It's not easy to cross beneath existing track, and I think once the excavation work is finished and the project's effectiveness is demonstrated, it will be used again."

The goal of the Market Creek Plaza project is to provide an economic infrastructure that will create jobs and generate equity opportunities for community residents. Setting a new standard for commercial and community development, the development strategy promotes community inclusion in the planning, construction and operation of the effort and provides an opportunity for community-based ownership and long-term wealth creation for the local area. Located at the intersection of Market Street and Euclid Avenue, the 20-acre Market Creek Plaza is being planned and built in partnership with local residents, businesses and organizations. The project developer is the Jacobs Center for NonProfit Innovation, a non-profit foundation that explores and implements new ways to strengthen under-invested neighborhoods through entrepreneurial projects, hands-on learning relationships, and the creative investment of resources.

During the construction phase, Market Creek Plaza is expected to generate 360 jobs with a payroll of $7.9 million while meeting a goal of 65 percent inclusion of minority and women-owned contractors on the job. When complete, the development is expected to generate hundreds of jobs and sales revenue in excess of $25 million.

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