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differ from the equation value(s) based on engineering judgement. 6. Evaluate the bridge TS&L on the basis of the scour analysis performed in steps 3-5, Modify the TS&L as necessary. o Visualize the overall flood flow pattern at the bridge site for the design conditions. Use this mental picture to identify those bridge elements most vulnerable to flood flows and resulting scour. o The extent of protection to be provided should be determined by: a. The degree of uncertainty in the scour prediction method. b. The potential for and consequences of failure. c. The added cost of making the bridge less vulnerable to scour, Design measures incorporated in the original construction are almost always less costly than costly than retrofitting scour countermeasures. 7. Perform the bridge foundation analysis on the basis that all stream bed material in the scour prism above the total scour line (step 4) has been removed and is not available for bearing or lateral support. All foundations should be designed in accordance with the AASHTO Standard Specifications for Highway Bridges. In the case of a pile foundation, the piling should be designed for additional lateral restraint and column action because of the increase in unsupported pile length after scour, In areas where the local scour is confined to the proximity of the footing, the lateral ground stresses on the pile length which remains embedded may not be significantly reduced from the pre-local scour conditions. The depth of local scour and volume of soil removed from above the pile group should be considered by geotechnical engineers when computing pile embedment to sustain vertical load. a. Spread Footinos On Soil. o Place the top of the footing below the design scour line from Step 4. o Make sure that the bottom of the footing is at least 6,0 feet below the stream bed as per AASHTO standards. b. Spread Footinos On Rock Hiohlv Resistant To Scour. Place the bottom of the footing directly on the cleaned 25