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91st Avenue

Location: Phoenix, Arizona
Client: Maricopa County Department of Transportation

Salt River Crossing at 91st Avenue

Through MCDOT’s On-Call, Hoskin Ryan provided a Design Alternatives Study and Preliminary Design Plans for roadway and bridge improvements to the 91st Avenue crossing of the Salt River. Historical flood records were used to determine the probability of inundation throughout a typical design life and a cost/benefit analysis was prepared. Six design alternatives were developed and analyzed with regard to service level and cost, impact to river hydraulics, existing utilities, and traffic. Historic gage data was used to determine a range of flood flow frequencies for design. Existing topographic and hydraulic information were input into GIS to create a HEC-RAS model upstream and downstream of the crossing.
Project Requirements / Unique Characteristics:

  • Improvements to Existing Roadway
  • Increasing the Amount of Days a Low Water Crossing
    is Passable During Flood Flows in the Salt River
  • Alternatives Cost/Benefit Analysis