Harford Road Bridge over Herring Run. Baltimore City, Maryland.
The existing structural condition of this historic bridge requires that it be replaced completely. The proposed roadway will carry four lanes of traffic along with a sidewalk and new bike lane on each side of the roadway. The proposed structure is a three-span continuous prestressed concrete superstructure with an approach slab at each end. The superstructure will be supported by reinforced concrete abutments and piers placed on spread footings founded on rock. Long retaining walls are required for the south approach to allow for the roadway widening. The completed project will include upgraded utilities, lighting, traffic signals, traffic signing and marking, as well as new storm water management facilities and improved landscaping elements.
WRA prepared a Categorical Exclusion with Programmatic Section 4(f) Evaluation for the historic bridge. Documentation included trilogy letters from MHT, DNR Wildlife Heritage, and DNR Environmental Review Unit. A temporary use agreement was also obtained from BCRP regarding temporary park impacts.
The visible rock in the project vicinity required an extensive subsurface exploration program with many rock cores being taken. In addition to providing exploration oversight, WRA’s geologists and geotechnical engineers analyzed the information obtained and provided recommendations for the structure foundations.
Hydraulic and scour analyses included predictive modeling of a complex layout including an existing multi-structure crossing composed of a 100-year old, triple-arch bridge elevated above a skewed existing pedestrian walkway and a proposed structurally in-kind replacement.
WRA performed maintenance of traffic alternatives analyses for the complete closure of Harford Road at the bridge including modeling existing traffic operations, developing detour routes, modeling closure traffic operations, and making recommendations for intersection improvements to accommodate detoured traffic. At the request of Baltimore City, the existing signals were replaced with modern mast arm signals. Due the heavy vehicular and pedestrian traffic volume, the existing street lighting
The length of the proposed bridge is approximately 290’-0”. The structural design challenges for this project including accommodating several large utilities as well as providing an aesthetic arch façade to meet the agreements made with the Maryland Historic Trust.