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BRIDGE ADVANCE PLANNING STUDY LAMBERT ROAD UNDERCROSSING(WIDENING) (Br. No. 55-0492) General Description The existing Lambert Road Undercrossing (Br. No. 55-0492) was constructed in 1971 and is a single span cast-in-place prestressed concrete box girder bridge carrying 10 lanes of SR-57 over Lambert Road in the City of Brea. The existing structure is approximately 177 feet long and approximately 144 feet wide. The existing structure has a skew angle of approximately 2 degrees. The existing structure would be widened to the east as part of the Lambert Road Interchange project Alternative 7A to accommodate a new northbound loop on-ramp. The proposed bridge geometry includes adequate width to accommodate a future northbound truck lane widening that would cause a shift to the proposed loop on-ramp. The proposed widening would range from 37.5 feet to 52.75 feet to accommodate a 12 feet wide ramp lane, 10’ wide right shoulder. The span configuration would remain as a single span 177’ long. Lambert Rd would be lowered about 12 inches to provide a minimum clearance of 15’-0” under the existing bridge and widened portion. Structure Description The proposed structure would be a single span cast-in-place prestressed concrete box girder with 6’-9” in depth with a skew of 2 degrees. The north abutment would be a diaphragm type approximately 3.5’ feet tall and with a pin bottom to match the existing movement and rotation characteristics. At the south abutment, the proposed roadway and sidewalk would be widened to within 5 feet of the abutment diaphragm. It is proposed to use a seat abutment with a drop cap. The drop cap height would be about 3.5’, to provide a pin at the approximate location as the existing structure. The abutment footing would be located 2’ below the proposed roadway surface. A special type 5 wall would be placed in front of the abutment to provide a constant width sidewalk. Additionally, a ground anchor wall would be needed under the existing south abutment. The wall types and costs were prepared under a separate APS within the Project Report, and are not included in this APS cost estimate. Falsework and Minimum Vertical Clearance The existing structure vertical clearance is 14’-9”, thus Lambert is proposed to be lowered to improve the existing vertical clearance to the minimum of 15’-0”. The 52.75’ widening at the existing cross slope of 1.5%, the maximum bridge depth of 6’-0” would be required. At this