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<br />Primary information sources are: <br /> <br />· Response to questionnaires distributed to SHAs and others under NCHRP <br />Project 24-7 "Effectiveness of Countermeasures to Protect Bridge Piers from <br />Scour" in September 1995. <br /> <br />· Follow-up telephone conversations with selected SHA personnel who reported <br />unique or successful countermeasures on the NCHRP Project 24-7 <br />questionnaires. <br /> <br />· Review of selection, design, and case study information in several key FHWA <br />publications including: <br /> <br />- Highways in the River Environment (HIRE, 1990) <br />- Evaluating Scour at Bridges (HEC-18, 1995) <br />- Stream Stability at Highway Structures (HEC-20, 1995) <br />- Hydraulics of Bridge Waterways (HDS-1, 1978) <br />- Design of Riprap Revetment (HEC-11, 1989) <br />- Brice et al. (1984) <br />- Brice and Blodgett (1978) Volumes 1 and 2 <br />- Brown et al. (1980) <br />- Clopper and Chen (1988) <br />- Clopper (1989) <br /> <br />· Review of selection and design information on countermeasures from other <br />agencies, including: <br /> <br />- State highway agencies <br />- U.S. Army Corps of Engineers (CO E) <br />- Transportation Research Board (TRB) <br />- Manufacturers' literature <br /> <br />· Personal experience of the authors and FHWA reviewers. <br /> <br />3.0 THE COUNTERMEASURES MATRIX <br /> <br />3.1 Overview <br /> <br />A wide variety of countermeasures have been used to control scour and stream instability at <br />bridges. The countermeasure matrix, presented in Table 1, is organized to highlight the <br />various groups of countermeasures and to identify their individual characteristics. The left <br />column of the matrix lists types of countermeasures in groups. In each row of the matrix, <br />distinctive characteristics of a particular countermeasure are identified. The matrix identifies <br />most countermeasures used by SHAs and lists information on their functional applicability to <br />a particular problem, their suitability to specific river environments, the general level of <br />maintenance resources required, and which states have experience with specific <br />countermeasures. Finally, a reference source for design guidelines is noted, where <br />available. <br /> <br />2 <br />