Applying 2D Modeling: Real Life Case Studies

Innovative Two-Dimensional Hydraulic Applications: Relocating a Channel and Replacing Two Structures Along a Western PA Highway Corridor

  • Rachel L. Tereska (NTM Engineering, Inc.)


An innovative two-dimensional hydraulic analysis was used to model two structure replacements and a channel relocation along the State Route 422 corridor in Western Pennsylvania. SR 422 divides the Curry Run floodplain and passes flood flows through two single span structures. During low flow, Bridge #1 conveys Curry Run and Bridge #2 conveys an unnamed tributary, but both bridges pass Curry Run’s flow during flood events. The goals of the project were to replace the existing structures with one, larger structure and improve the alignment of Curry Run. The 2D model used the TUFLOW finite difference program in the state-of-the-art Surface-water Modeling System (SMS) software.

The Curry Run channel was straightened in the 1950s as part of the SR 0422 widening project, but has been an ongoing maintenance issue with roadway embankment erosion and the inefficient openings due to the severe skew of the stream. During low flow, a straightened reach of Curry Run runs along the embankment toe until the channel makes a sharp turn through Bridge #1. Curry Run is severely skewed to Bridge #1 and causes significant erosion along the roadway embankment and at the bridge opening. During flood events, Curry Run flows through Bridge #1 and Bridge #2 and overtops the roadway embankment.

A proposed twin cell structure will convey Curry Run under SR 422 in a new location that is aligned with the upstream channel. The straightened reach of Curry Run will be eliminated and the relocated reach will meander through the downstream floodplain. The proposed 2D results were used to design the hydraulic opening of the proposed structure and evaluate impacts to the 100-year floodplain. The proposed design drastically improves the hydraulic conditions at the site by improving channel alignment, decreasing erosion potential, reducing roadway overtopping, and eliminating a redundant structure.

How to Cite:

Tereska, R. L., (2014) “Innovative Two-Dimensional Hydraulic Applications: Relocating a Channel and Replacing Two Structures Along a Western PA Highway Corridor”, National Hydraulic Engineering Conference 2014 1(2014).

Rights: Copyrgiht © 2014, Rachel L. Tereska

Publisher Notes

  • Panel moderated by Wesley Peck, TDOT.
  • About the Presenters: Ms. Rachel Tereska is a Principal of NTM Engineering, Inc., a women-owned business that specializes in water resources, structural engineering, and technical course development and instruction. Ms. Tereska earned her B.S. and M.S. in Civil Engineering from The Pennsylvania State University and holds Professional Engineering licenses in Pennsylvania and Delaware. She has 13 years of experience performing hydrologic and hydraulic modeling, bridge scour analysis, waterway permitting, and floodplain studies. She is a lead instructor for five of H&H-related courses that NTM developed for PennDOT. Ms. Tereska conducted PennDOT’s first two-dimensional (2D) hydraulic analysis using the Surface-water Modeling System (SMS) and is currently leading the analyses of several 2D models for PennDOT transportation projects in complex river environments. Ms. Tereska has presented on 2D modeling applications to the American Society of Highway Engineers (ASHE), Floodplain Management Association (FMA), National Association of State Floodplain Managers (ASFPM), and PennDOT. Additionally, Ms. Tereska is a panel member for the federal National Cooperative Highway Research Program (NCHRP) Scour at the Base of Retaining Walls and Other Longitudinal Structures Project.

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Published on
20 Aug 2014
Peer Reviewed