This stormwater bioretention facility, built into a terraced retaining wall adjacent to the College Creek Bridge abutment, is one of five such units serving the two bridges.
Decorative pavers in the Weems Creek Bridge median form a serpentine design representing a meandering creek. Water runoff drains to the middle of the median for collection. The 15-foot-wide median can be removed if necessary in the future to provide additional capacity. Photos: KCI Technologies Inc.
Gateway To The Capital
The 1200-foot-long College Creek Bridge was transformed into an architectural gateway to Annapolis. Neoclassical pilasters with wrought iron arches frame the city's colonial spires. Rehabilitation work to the 16-span steel beam bridge included replacing the steel girders and concrete deck, replacing pier caps, and repairing pier columns and footings.
The Weems Creek Bridge, farther from the city, sports a more modern streetscape that blends with the surrounding residential community. Extensive landscaping softens the brick and pilaster design. The new bridge structure has five bridge spans, instead of eight as in the previous structure, thus reducing the cost.
The bridges span the fragile Weems and College Creek watersheds, which had been degraded by years of surrounding development. The bridge rehabilitation project provided the opportunity to improve environmental conditions around both creeks by planting trees, creating wetlands, and providing stormwater management. Five new bioretention facilities were built within the limited right of way to capture and purify stormwater flowing off the bridge decks before the water enters the creeks. Each facility was landscaped with native trees and grasses.
Another environmental concern was the potential impact of heavy machinery operating on the steep slopes adjacent to the tidal wetlands. Double-layer silt fences, turbidity curtains, check dams, and storm-water management ponds were used to protect the creeks from sediment and pollutants caused by construction activities. MSHA hired an environmental consultant to inspect the project daily. In addition, MSHA agreed to test the creek water periodically before, during, and after construction—a total of four years. Test results so far indicate construction did not affect water quality and the bioretention facilities are working as planned.
The Weems Creek Bridge was widened not only to accommodate future growth but to enable all lanes to remain open during construction and shorten construction from three to two years. Tear-down was accomplished in two phases, during which traffic was shifted first to one side, then the other, while the opposite side was removed and replaced. Removing the existing 4-foot concrete median and narrowing the lanes made it possible to keep all lanes open during peak traffic hours.
On the College Creek Bridge, at least one lane had to be closed during construction. Rather than shut down a lane in either direction permanently, MSHA used a programmed reversible lane system operated by overhead signal lights, provided by Rummel, Klepper & Kahl Engineers LLP, Baltimore. This was an efficient, cost-effective alternative to the movable barrier system used on previous projects.
Construction was completed and the bridges opened to traffic on schedule in the fall of 2006. So far, the project has garnered an Award of Merit from the Maryland Chapter of the American Council of Engineering Companies, an Award of Excellence from the Maryland Chapter of the American Concrete Institute, and a 2006 award in the Bridges Category from Mid-Atlantic Construction Magazine.
“The project will serve as a model for context-sensitive design in Maryland,” says MSHA's Roberts. “This approach to working with the community was a big step forward for us.”
— Diana Granitto is a freelance writer based in Hoffman Estates, Ill.
Project: Maryland Route 70 (Rowe Boulevard) over Weems and College Creeks
AEC firm: KCI Technologies Inc.
Cost: $36.2 million
Project delivery method: Design-bid-build
Community outreach: Citizen task forces, educational brochures, “MD 70” Web site, public opinion survey
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