Countermeasures Analysis for an Existing Scour Critical Bridge (Bridge # 1200) Over Río Grande de Loíza at Road PR-3 Carolina, Puerto Rico

Abstract

Scour is the most common reason for the failure of highway bridges in the United States. In Puerto Rico, there are more than 350 scour critical bridges. Bridge 1200 has been classified as a scour critical bridge by the Puerto Rico Highway and Transportation Authority (PRHTA). Scour along the abutments and piers supports is the key parameter to calculate the appropriate protection for the bridge piers and abutments. Models used for analysis were: ArcMap (GIS), HEC-HMS, HEC-RAS 4.1.0, HEC-18 and HEC-23. The investigation has shown contraction scour depths up to 1.5m and pier scour depths up to 5.27 m for the 500yr event. Abutment scour depths up to 2.32 m were found for pressure flow condition. Due to its proven performance and availability, rock riprap was recommended as a scour countermeasure. Sizes up to 9in (60 pounds) for abutments and 24 in (1/2 ton.) were calculated. Key Terms - HEC-HMS and HEC-RAS Analysis, Scour Countermeasures, Scour Critical Bridge, Total Scour.