The Arkansas State Highway Department plans to build a new two-lane highway bridge, parallel to and approximately 50 feet (15.2 metres) downstream from the centerline of the existing U.S. Highway 167 bridge, over the White River at Batesville. The present bridge will be altered and remain in service, thus providing a four-lane crossing after completion of the new bridge.
The State Highway Department requested a hydraulic analysis of the 5O-year flood at the site, considering the effect of upstream flood storage in existing (1974) reservoirs. The purpose of this study was to determine for the regulated 50-year food: (1) the discharge and elevation of peak flow and resulting backwater with existing bridge in place; (2) the discharge and elevation of peak flow and resulting backwater if an additional bridge of the same length, parallel to and 50 feet (15.2 metres) downstream from the existing bridge, is added; and 3) the reduction in length of relief span of proposed four-lane bridge that could be made without flooding existing buildings on the north bank of the upstream flood plain.
Information is provided in this report to assist the Highway Department in deciding upon the most practical and economical river crossing within existing limitations. Floodflow characteristics of the design (50-year) flood are summarized in table 1 for (1) existing bridge and embankment, (2) proposed four-lane bridge the sane length as present structures, (3) proposed four-lane bridge with length of relief span reduced to 3,000 feet (914 metres), (4) Tenth of relief span reduced to 2,000 feet (610 metres), (5) length of relief span reduced to 1,000 feet X 305 metres), and (6) without a relief span.
All elevations listed in this report are referenced to highway datum, which is mean sea level.
