Hydraulic Control

Peggy A. Johnson, Professor of Civil Engineering at Penn State, paj6@psu.edu, 814-865-1330

Hydraulic Control of Flow through Bridges

Controlling Aggradation at Bridges. Aggradation at bridges has been experienced in many parts of northern Pennsylvania, causing the bridge waterway openings to be reduced. At multiple span bridges, aggradation at one or more spans can lead to the potential for increased contraction scour at the remaining spans. In addition, the reduced waterway opening can cause overtopping of the bridge deck during flooding, as well as an increase in upstream flooding due to the inability of the opening to convey the water and sediment mixture. The objective of this project, funded by PennDOT, is to create a methodology that will ultimately reduce maintenance costs at waterway structures where heavy sediment transport and aggradation occur at bridges. The project results will identify methods to improve maintenance and design procedures, evaluate and rank candidate procedures, and create new maintenance and design guidance for the selected procedures.

References
Johnson, P.A., Hey, R.D., Horst, M.W., and Hess, A.J., 2001. Aggradation at bridges. Journal of Hydraulic Engineering, ASCE, 127(2), 154-158.

sediment at bridge

Hydraulic Control of Local Scour at Bridge Piers and Abutments. A variety of flow alignment devices, such as vanes and cross vanes, have been used in recent years primarily as treatment for bed and bank erosion in stream stability projects. The use of these structures to align flow through a bridge opening could have the effect of moving scour away from the abutments and piers into the center of the channel. The objective of this project was to evaluate the effectiveness of vanes, cross vanes, and w-weirs for preventing local scour at bridge abutments and to suggest the optimum design parameters based on laboratory experiments.

Creating Transitions at Bridges. The number of stream restoration and stabilization projects being implemented is rapidly increasing. At road crossings, a transition must be created from the restored channel through the bridge or culvert opening. An ideal transition will convey flood flow up to the design standard for the bridge and convey sediment without causing additional scour at the bridge piers and abutments. In this project we adapted hydraulic flow control structures commonly used for stream restoration projects for the purpose of creating such transitions at bridges.

References
1. Johnson, P.A., Tessier, M. Hey, R.D., and Rosgen, D.L., 2001. The use of vanes for local abutment scour reduction. Journal of Hydraulic Engineering, ASCE, 127(9), 772-779.
2. Johnson, P.A., Hey, R.D., Brown, E.R., and, Rosgen, D.L. 2002. Stream restoration in the vicinity of bridges. Journal of the American Water Resources Association, 38(1), 55-67.
3. Johnson, P.A., 2002. Incorporating road crossings in stream restoration projects. Ecological Restoration, 20(4), 270-277.