Final Scope

State DOTs undertake hundreds of construction projects each year that affect, and are affected by, streams and rivers. These include replacement and rehabilitation of bridges and culverts, as well as new construction and rehabilitation of highways in stream corridors. The hydraulic design standards for the completed bridge, culvert or highway are well established. However, there are elements of risk involved in any temporary occupancy of a waterway for construction, including: personal safety risks, economic risks to the transportation agency and contractor from delays or damage, and environmental risk from unanticipated flooding. These risks are associated with a wide range of structures, from minor drainage crossings to major river structures. While some states may have well-defined policies and methods to address hydraulic considerations for temporary construction facilities, other states may address these issues on a case-by-case basis.

The objective of this synthesis is to document state DOT hydraulic engineering practices for construction and temporary facilities in streams and rivers.

Information to be gathered includes (but is not limited to):
• Existing policies, practices, and specifications for temporary facilities in water;
• Bridge foundation cofferdams and level of protection against flooding;
• Waterway temporary diversions around construction work areas;
• Storm frequencies being used ¬for temporary construction;
• Temporary causeways in rivers to allow access for bridge pier construction or demolition;
• Hydrologic methods being used for temporary structure sizing;
• How risk for temporary structures is quantified (e.g., through programmatic data driven or qualitative methods); and
• Methods to evaluate trade-offs for actions that improve construction access but increase risk of flooding damages (e.g., increased height of temporary causeways).

Information will be gathered through a literature review, a survey of state DOTs, and follow-up interviews with selected agencies for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.