MoDOT Interstate 44 flood study and alternatives investigation

Project Summary

Little Piney Creek passes under Interstate 44 and merges into the Gasconade River near Jerome, Missouri. Short-term flooding issues have affected I-44 in this vicinity since its original construction. In the last 10 years, the frequency and duration of the flooding issues have increased; as a result, I-44 has been closed to traffic three times in the last decade. In 2015, a record storm resulted in flooding up to 6 feet deep along a half-mile section of I-44, and the interstate was closed for three days. In spring 2017, another storm caused up to 8 feet of flooding on the same section.

Because I-44 is the second-most-used corridor in the state, the Missouri Department of Transportation (MoDOT) selected Hanson to analyze the current hydraulic conditions that have led to the interstate flooding and closures, develop alternatives to keep interstate traffic moving through the affected area during future flood events and prepare conceptual plans for MoDOT’s preferred solution.

The hydraulic study determined I-44’s overtopping frequency based on analysis using a HEC-HMS and HEC-RAS model. Hanson’s hydraulic analyses determined design flood volumes, available floodplain storage and peak flow rates from potential theoretical design storm events. In addition, recorded rainfall and runoff data from the May 2017 storm was quantified, simulated and calibrated in the hydraulic model so improvement alternatives can be tested against this record event.

The alternatives study will include cost/benefit analyses for two improvement options: raise I-44 above the recent flood events or construct an outer roadway to I-44 above the recent flood events at the flood-prone location. Conceptual plans and an estimate will be prepared for MoDOT’s preferred option.

Additional services will include field surveys; geotechnical, structural and roadway conceptual design; and an environmental and historical screening of the impacted area.