CTLGroup developed a robust and cost-effective remote monitoring solution to evaluate whether the Calumet Avenue (U.S. 41) Bridge over the Grand Calumet River in Hammond, Indiana was undergoing structural movement as a result of construction of a sanitary sewer force main adjacent to the bridge bents. The force main construction was part of a major infrastructure improvement project by the Sanitary District of Hammond, Indiana. The contractor performing the work was required to meet a stringent “no settlement” requirement that was established by the Indiana Department of Transportation, the agency that owned the bridge.
The force main construction required deep excavation beneath the bridge between two bents on a side channel of the river. The CTLGroup designed monitoring system included biaxial tiltmeters to measure rotation of the bents on either side of the excavation. Liquid pressure-based settlement sensors were also installed at various points along the bents, as well as the north abutment of the bridge. Data loggers located in a central station on one of the bents were used to record the tilt and settlement data. Data was transmitted wirelessly to a server located at CTLGroup’s office for aggregation and communication.
CTLGroup provided a customized website for authorized data access to key stakeholders. The website displayed data both graphically and in tabular formats. In addition to the website, CTLGroup submitted an automated weekly report of measurements.
Data was recorded prior to commencement of major excavation activities to identify normal data fluctuations in movement due to weather conditions, ambient traffic, etc. The system ran continuously for the entire six-month duration of construction activities adjacent to the bridge. CTLGroup’s monitoring solution helped the contractor performing the work by providing an evidence-based record to show that their construction activities had no structural impact on the bridge.