HYDRAULIC DESIGN OF INTERSTATE HIGHWAY 35 AT WACO CREEK, USA

Flood Cloud was used to run a HEC-RAS 2D model of the Interstate Highway 35 within the City of Waco to evaluate numerous designs of hydraulic structures to develop an optimised solution for the Texas Department of Transportation (TxDOT). TxDOT is undertaking a transportation construction project along the Interstate Highway 35 (IH-35) at Waco Creek in Waco, Texas. This project includes the widening of the IH-35 by raising the main lanes, eliminating the 12th Street overpass, and constructing a new bridge for the IH-35 main lanes over 12th Street.​​

KEY FACTS

• Software run with Flood Cloud: HEC-RAS 

• Time to run 230 simulations with normal approach: 630 hours

• Time to run 230 simulations with Flood Cloud: 2.75 hours

• Time saved using Flood Cloud: 26 days

• High performance computers cost: £0

• Extra licence costs: N/A

• Additional labour costs: £0

The Waco Creek Project is located in the Waco Creek watershed within the City of Waco. Waco Creek is designated Federal Emergency Management Agency (FEMA) Zone AE with a floodway at IH-35 and with no hydrologic and hydraulic effective models.

The Waco Creek Project changes the landscape of the Waco Creek crossing and the stormwater drainage system in the proximity of Waco Creek at IH-35. Historically, the City of Waco experienced a 50-year flood event in May 1989 which overtopped IH-35 main lanes and caused significant overland flooding resulting in the closure of the highway.

TxDOT handed the responsibility to Jacobs to perform general engineering services for the project, conduct special studies and develop a White Paper focused on drainage in the area of the project near Waco Creek. Jacobs conducted analysis using the City of Waco’s 2D HEC-RAS model for the Waco Creek Crossing at IH-35 to analyse alternatives that use culverts to convey drainage through the IH-35 right-of-way.

Jacobs developed 46 drainage alternatives based on the required criteria, by iteratively adjusting flow lines and widths and adding multiple standard-size box culverts in 3 to 4 groups to provide conveyance while considering factors including cost, ease of access, additional capacity beyond the proposed design, and construction schedule. Each alternative was analysed for a range of design flow events from 5-year to 100-year flow events.

The combination of 46 alternatives and 5 design flow events each have resulted in 230 2D unsteady-state simulations. Because of the fine resolution of the 2D model mesh size used, each simulation took about 2.75 hours to complete. The total computation time required for evaluating the project alternatives exceeded over 600 hours.

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The time taken to run simulations on local computers and evaluate each design alternative sequentially had created a bottle neck for the project causing delays in the schedule and an increase in contractor costs for TxDOT. To expedite hydraulic evaluation of the drainage designs, Jacobs used Flood Cloud to run Waco 2D model simulations in the cloud. Flood Cloud facilitated in running multiple alternative simulations simultaneously without the need for procuring additional local computers. About 60% of the total simulations were run using Flood Cloud. Doing so accelerated the progress on optimisation of drainage design for the project and helped in meeting schedules for detailed design and construction tasks.

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Flood Cloud’s real-time dashboard was extremely helpful to monitor progress of simultaneous batch runs, providing updates on percentage complete and download status. The “Test mode” within the application was used to test simulations locally before sending to the cloud. This enabled the user to perform quality control on the model runs to check if the models were set up correctly and to avoid wasting cloud computing credits. Another unique feature of Flood Cloud is the ability to download simulations results to any computer at any time after the simulations are completed in the cloud. This feature allows for better organisation and archiving of model data for documentation and future use.