Bridge #19 over Muddy Boggy Creek

GUY developed a design to re-align and reconstruct 1.2 miles of roadway and to replace a historic, structurally deficient truss bridge built in 1919. The existing bridge was not adequate for school bus traffic. In addition, the roadway flooded multiple times per year, forcing area drivers to take an approximately 1 hour detour route.

A challenge in designing this project is that it is located in what is considered some of the best wetlands in the state. In order to identify an alignment and bridge configuration with minimal wetland impacts and a reasonable cost, GUY performed an alignment study with various bridge length scenarios to determine the best cost versus wetland impacts. The original proposed alignment and bridge replacement impacted 22 acres; GUY was able to modify the design to limit the wetland impact to only 1.8 acres.

The design incorporates a long bridge length to span over much of the wetland area. In addition, the roadway was raised to provide protection for the 25 year storm. An overflow bridge structure was added to ensure the new, raised roadway would not change the base flood elevation.

Another challenge was that nearby properties have an extensive levee system that was difficult to model. Bridge hydraulics were performed using HEC-RAS.

The project also included both environmental studies and wetland mitigation for USACE and for NRCS. A wetland mitigation plan was included in the construction plans.


SH-20 over Spavinaw Creek

Bridge #19 Over Muddy Boggy Creek


Choctaw County

Expertise Provided:

Bridge and roadway design

Bridge and roadway geometrics


Hydrology and hydraulics

Structural design

Utility relocation coordination

Project management


Right of way mapping

Right of way determination and documentation

Stormwater pollution prevention plan


Wetland mitigation

Cost estimating

404 permitting

Geotechnical Investigation


Choctaw County, OK