The County of Madera in cooperation with Caltrans had orginally programmed the Avenue 25 Bridge over Ash Slough under the Federal Highway Bridge Program as a scour countermeasure project.  The bridge was constructed in 1954 and consists of a 16 span continuous conventionally reinforced concrete slab bridge measuring 343 feet in length.  The existing bridge is supported on Raymond step taper piles and pile extensions at both the piers and the abutments.  Due to past instream gravel mining operations and head cutting from downstream along both Ash Slough and the Eastside Bypass, up to approximately 9 feet of channel bed degradation has occurred between Piers 4 through 10.  In addition to the ongoing channel bed degradation, both the traveled way width and existing barriers are also deficient.  After evaluating the pros and cons of a scour countermeasure, retrofit and rehabilitation, and a replacement using a life cycle cost analysis comparison, Cornerstone concluded that the replacement bridge was the most promising alternative.  Caltrans District 6 Local Assistance and Caltrans Office of Structures Local Assistance concurred with our recommendation and reprogrammed the bridge for replacement.  The bridge was replaced with a nine span, 320 ft. long slab bridge supported on 30" dia. CIDH piles.