Brudis & Associates, Inc. (BAI) was responsible for structural design for the replacement bridge, including foundations and abutments. The replacement structure was widened to accommodate a minimum 24-ft. wide open section roadway with traffic barrier, and the span length was increased to improve bridge hydraulic performance.
Structural Design: The new structure was designed using LRFD Bridge Design Specifications for HL-93 load, including ratings for Maryland Legal Vehicles (H15, HS20, Type 3, Type 4 and 3S2) and Harford County fire truck loads. The replacement structure was designed using innovative construction methods including Geosynthetic Reinforced Soil (GRS) – Integrated Bridge System (IBS) technology, which utilizes alternating layers of compacted granular fill material and geotextile reinforcement to provide support for the bridge abutments, and prestressed concrete slab and deck overlay superstructure. The replacement structure design provides reduced construction time and costs, and was designed to be constructed by county forces using common equipment and materials.
Geotechnical & Surveying Services: BAI was responsible for providing GPS survey control since the project was in a remote rural area, field topographic mapping, stream cross sections, metes and bounds survey, and right of way/easement plats. Geotechnical engineering services included soil borings, laboratory testing, and geotechnical analysis and report for the design of the replacement structure foundations.
Roadway Design: BAI designed the replacement structure approach roadways including horizontal and vertical alignment, according to AASHTO sight distance criteria for a minimum 35 MPH design speed. The plans also included traffic safety barriers, cross sections, pavement details, and drainage.
Hydraulic, SWM, Erosion & Sediment Control, & Environmental: BAI provided hydraulic design for the replacement bridge waterway including Hydrologic Analysis report using GIS-HYDRO and TR-20 to determine flood frequency discharge curves (2, 10, 25 and 100-year) using ultimate zoning land use and development, hydraulic analysis using HEC-RAS to improve the hydraulic conditions and limit increase of the 100-yr. flood elevation, and scour analysis using MD ABScour to evaluate the contraction and abutment scour for 100 and 500-year storm events and to determine depth of foundations. BAI provided environmental site design including wetland delineation and report, forest/tree stand delineation, and MDE Joint Permit Application for waterway construction. BAI also provided maintenance of stream flow plans for the replacement bridge construction that included sand bag diversions, temporary bypass pipes, and other measures necessary to divert stream flow during excavation and construction of the bridge foundations.