Unforeseen Utility Installation Leads to Unique Bridge Design

Introduction

As part of the planned construction on the K-32 highway, the Kansas Department of Transportation (KDOT) needed to replace two bridges at the K-32/Turner Diagonal/Kaw Drive Interchange as they were nearing the end of their service life. GBA was tasked to identify a solution to replace the eastbound and westbound bridges that have been standing for over 60 years.

Discovery & Design

GBA was responsible for the road, traffic and bridge design for the two bridge replacements at the interchange. This project was unique because the two bridges needing replacement spanned the Union Pacific Railroad and an additional roadway.

The team conducted a study to look at alternative ways to replace the bridges. The two existing bridges sat at different angles to each other. Potential layouts included configuring the bridges to sit parallel to each other or situate the bridges to cross at different locations. It was ultimately decided that the existing configuration was the best option due to the positioning of the railroad crossing.

Communication was key with all stakeholders. Throughout the project, GBA had to coordinate construction with the railroad, multiple gas line companies, and the Unified Government of Wyandotte County to determine detour routes, road closures, and bridge placement.

Challenges Faced

During the design and planning phase, the team discovered multiple utility lines in the ground below the bridge’s foundation, including eight high-pressure gas lines. The team planned to locate one of the bridge abutments in the open space between the gas lines to avoid relocating the lines.  Despite early coordination with gas line companies, as the team neared the end of the project, they discovered that an additional gas line had been installed in the space to be occupied by the bridge abutment. This sent the team back to the drawing board.

Not only was the bridge’s design affected by the gas line’s location, but construction practices also needed to be altered to avoid damaging the lines. Typically, on bridge foundation and bridge abutment construction, contractors drive piles into the soil until they reach the needed bearing capacity for the structure. For this project, the contractor will pre-drill below the level of the gas lines and use a vibration monitoring system, similar to what might be used to detect earthquakes, to closely monitor the ground vibrations created during construction and the possible effect on the gas lines.

Construction Timeline

Bridge construction is anticipated to be completed by the end of 2025. To learn more about this project, visit: here