The USD 135 million M-1 Rail project will be an urban fixed-rail system connecting downtown Detroit, Michigan, to the New Center area along Woodward Avenue (M-1). The route is 3.3 miles long with 11 station stops. As part of M-1 Rail’s utility investigation, HNTB and its partner, Surveying Solutions Inc. conducted a detailed investigation of more than 700 manholes along Woodward Avenue using a state-of-the-art scanner and traditional survey methods.
The survey data verified the dimensions for tops of pipes and manhole widths and depths, and provided correct digital measurements of other features within each structure. This data was then incorporated into the project’s 3D model created from MicroStation, InRoads, and InRoads Storm & Sanitary. Bentley Navigator was used to perform clash detection and produce a list of anticipated utility impacts. Once the conflicts were refined by the utility owner, resolutions were discussed with each company to provide better outcomes.
The utility investigation gathered information from public and private utilities, uncovered risks in the project area, established a clear picture of the final utility configuration, estimated the capital costs of relocations, and identified potential construction impacts related to utilities. The process provided increased project confidence and ultimately reduced costs for all parties. The USD 280,000 advanced utility investigation helped avoid more than USD 2 million in utility impacts.
The dynamic scanner, which is able to scan a 50-foot-deep manhole in less than three minutes, took continuous photos of the insides of the manholes. The LiDAR survey produced a 3D point cloud of the interior of each manhole, which produced the horizontal and vertical depiction of the underground features within the Woodward Avenue corridor. The 3D model, built with Bentley technology, allowed the project owner to communicate visually with the utility owners about how to minimize utility impacts.