Spring 2019

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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REHABILITATING MARYLAND ROUTE 195 (CARROLL AVENUE) BRIDGE OVER SLIGO CREEK by Fred Braerman, Johnson, Mirmiran & Thompson, and Maurice Agostino, Maryland Department of Transportation, State Highway Administration The Maryland Route 195 (Carroll Avenue) Bridge over Sligo Creek, located in the Washington, D.C., suburb of Takoma Park, Md., is a nonredundant, open- spandrel, reinforced concrete arch bridge that carries one lane of traffic in each direction, with sidewalks on both sides. Nearly 80 years after being constructed in 1932, the bridge became rated structurally deficient in 2011, when routine inspections found extensive and worsening deterioration of the bridge deck. While evaluating options for this aging structure, Maryland Department of Transportation (MDOT) officials recognized the functional and historic significance of the bridge and concluded that replacing it with a girder-type structure would not be the right solution. Instead, MDOT decided that rehabilitation was the appropriate strategy, a decision that was well received by the community. A construction contract was awarded to the prime contractor for $9.3 million in October 2015, and the project was completed less than one year after the bridge was closed to traffic. The bridge was reopened ahead of schedule in June 2017. Planning and the Decision Process Originally built with non-air-entrained concrete and black reinforcing steel, the 220-ft-long Carroll Avenue Bridge has span lengths of 65, 90, and 65 ft and traverses Sligo Creek Parkway, Sligo Creek, and a county-owned trail for hiking and biking. In 2011, the MDOT State Highway Administration (SHA) Office of Structures contracted t h e b r i d g e d e s i g n e n g i n e e r t o perform an in-depth field inspection, structural analysis, and assessment of the bridge. Because the bridge was eligible for inclusion on the Historic Register and on MDOT SHA's Priority 1 list for preservation, the bridge design engineer focused on rehabilitation strategies. The bridge design engineer's findings indicated that replacement of all portions of the bridge above the arch ribs would be required to address the extensive deterioration of the deck, floor beams, columns, and spandrel arches. The plan was to repair and preserve the existing substructure units and arches while reconstructing the remainder of the bridge from the arch ribs up. The complete reconstruction of the bridge above the arch ribs would allow for the structure to be widened curb-to-curb by 2 ft, creating 11-ft-wide travel lanes. The community wanted wide shoulders to make biking safer in this residential area. Additionally, the rehabilitation would include new sidewalks on both sides of the bridge, with new sections of sidewalk extending past the ends of the bridge to provide improved pedestrian access to all four approaches to the bridge. During the planning stage, several project-specific challenges were noted. The bridge's location, 50 ft over a ravine within the floodplain of Sligo Creek, constrained the project site. Existing utilities on the bridge and adjacent overhead utilities on the west side of bridge would have to be temporarily relocated to allow for construction. Sligo Creek Parkway, located beneath the southernmost span, was a major commuter route within this congested suburb, and a heavily used hiker-biker trail located beneath the northernmost span would need to remain open during rehabilitation. Project leaders conducted extensive public outreach to gain input and support from the community. For example, they held multiple public meetings and coordinated plans with Washington Adventist Hospital on the north side of the bridge, the Takoma Park City Council, the Montgomery County Transit bus system, Montgomery County Parks, and local emergency responders. Design Challenges When a bridge is rehabilitated, its geometry must be maintained. The existing Carroll Avenue Bridge was profile MARYLAND ROUTE 195 (CARROLL AVENUE) BRIDGE OVER SLIGO CREEK / TAKOMA PARK, MARYLAND BRIDGE DESIGN ENGINEER FOR REHABILITATION: Johnson, Mirmiran & Thompson, Hunt Valley, Md. PRIME CONTRACTOR: Kiewit Infrastructure South, Omaha, Neb. REINFORCING STEEL SUPPLIER: Gerdau, York, Pa. OTHER CONSULTANTS (ROADWAY AND TRAFFIC DESIGN): Mercado Consultants Inc., Ashton, Md.; Sabra and Associates Inc., Columbia, Md. 12 | ASPIRE Spring 2019 P R O J E C T

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