PennDOT Route 18 Frankfort Road Bridge Replacement

Challenge:

To improve infrastructure statewide, the Pennsylvania Department of Transportation (PennDOT) initiated a 12-year program to improve bridge and road conditions, enhance technological advancements, and promote safety. In 2025, one of the initial projects undertaken was the Route 18 Frankfort Bridge Replacement in Monaca, PA. The new bridge cost $25.3 million and was a crucial improvement to ensure motorist safety.

The project specified base cleanliness for 43 drilled shafts that could not exceed 0.5 inches of debris over 50% of the shaft bottom and no location greater than 1.5 inches. Drilled shaft base cleanliness is not always specified by PennDOT, but the designer realized the benefits of assessing base cleanliness prior to concrete pour including evaluation of shaft conditions that match design assumptions, assessment of base consistency from cone penetration resistance, and objective acceptance with qualitative analysis.

Installation Method:

Due to the number of drilled shafts specified for testing, a GRL engineer was onsite to train the project personnel on operation of the Shaft Quantitative Inspection Device (SQUID66) equipment. Once the borehole was drilled and the cleanout bucket was utilized for the first time, the onsite contractor would quickly attach the SQUID66 to the drill rig’s Kelly bar. The SQUID66 was deployed in each shaft, collecting data at the base in 5 locations, one in each quadrant (east, west, north and south) and one in the center of the base. The SQUID66’s mud plates were displaced when debris was encountered, and penetrometers recorded the force vs displacement measurements. Each test lasted 10 to 15 minutes and if the test results revealed debris thickness higher than specified, the cleanout bucket was reattached to the Kelly bar for another run. The quick nature of the SQUID66 testing allowed construction schedules to proceed without delay, providing contractors quantitative results and therefore increased confidence with respect to the base cleanliness. While the contractors collected the data, a GRL engineer remotely viewed the data in real time via SiteLink^® Remote Technology, allowing for collaboration with the crew onsite and immediate decisions to be made. SiteLink remote technology allowed scheduling flexibility without sacrificing expert oversight.

Results:

24 of the 43 drilled shafts were approved in the initial SQUID66 testing and all other shafts were approved once additional cleanout methods were utilized. Every shaft ultimately met the project specifications prior to concrete placement. All SQUID66 tests were completed in less than 15 minutes with most tests completed in under 10 minutes, keeping the operation’s pace practically undistracted. Utilizing the remote capabilities saved significant costs in the engineer’s travel time. Figure 1 displays a sample of a drilled shaft after SQUID66 testing. The data from each penetrometer is displayed in numerical form, showing a quantitative measurement of force vs displacement.