SPT GyroLogic™ performs a successful
survey operation for the Milan Metro

Stockholm Precision Tools successfully performs 100 independent horizontal survey operations for the Milan Metro ensuring a safe structure for the new Metro Line

survey operation
Figure 1. SPT Technical Engineer with the GyroLogic™

Stockholm Precision Tools recently performed multiple successful gyro surveys for the Milan Metro that involved performing a continuous survey operation on 100 horizontal boreholes.  The wells were drilled to ensure a safe passage for the new platforms and the metro line. Due to the complexity of the project and the need to avoid survey data errors, a highly accurate survey tool, unaffected by magnetic disturbance, which could accurately measure all the 100 boreholes without any downtime was required.

As time was of the essence, SPT GyroLogic, a highly accurate and extremely reliable directional survey tool, was deployed, along with our technical engineer to train the clients team to initiate the survey operation. Our technical expert arrived at the site to train the personnel on how to correctly assemble the tool for this particular operation and ensure they followed the correct steps and protocols for a fast and accurate survey, and lastly, how to effectively use the data obtained after the survey. Our tool exports the data in multiple industry-standard formats, for example, PDF, Excel, CSV, LAS, DXF. In this particular operation, the team required the data in CSV format, ensuring a 3D model is obtained for each of the independent holes that were surveyed.

civil engineering projects
Figure 2. The platform that will connect the station with the new metro line.

A section of the metro line and platform can be seen in the above image, with the holes marked for the survey operation (Figure 2). Each of the holes required independent surveys, making sure that all of the 100 holes along the 5 km of the metro line were drilled accurately (Figures 3, 4 and 5).

gyro survey tool
Figure 3. Milan Metro new station
drilling operation
drilling operation preparation
Figure 4-5. The holes in the wall are injected with cement to solidify the structure

Using gyro survey tools in such civil engineering projects comes with a variety of complexities and challenges that are very different from the ones we face in the Mining or Oil & Gas industry. Making sure that the tools are not affected by any sort of magnetic disturbances and able to export the data in the correct formats are critical factors for drilling holes in such close distance. Even 1 degree of error can have a disastrous impact on the project.

Initially, 14 boreholes were surveyed, and the process of configuring the data obtained during the surveying was completed using the SPT software, to which we had programmed with the starting coordinates of each borehole for use as a measurement reference.

Mirko Macari, surveyor in STR 92 -engineering company involved in the project-, remarked: “Thanks to the support from the technical engineer in the initial training, and the user-friendliness of the tool, we were able to efficiently complete the operation to the satisfaction of the client. After the first two days of training, our on-site engineers were able to independently perform the survey operations with ease, thanks to the remote technical support from SPT.”

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