Complex construction projects benefit from faster, data-driven decisions, and improved timeliness and quality when all stakeholders have access to accurate, up-to-date engineering design, survey, and construction data via a cloud-based common data environment.
When faced with schedule pressures and stringent accuracy requirements on the Bergünerstein Tunnel project, Donatsch + Partner AG, a full-service surveying company based in Switzerland, chose to adopt a cloud-based workflow. The integrated cloud process was new for Donatsch, prime construction contractor Rhomberg Bahntechnik AG, and design company Amberg Engineering AG.
Trimble Connect®, a cloud-based common data environment (CDE) and collaboration platform, enabled the seamless transmission of data and easy access to the most current design. With participation from all parties, the centralized data approach resulted in the efficient management of design updates, expedited volume calculations and comparisons of as-builts to design, facilitated communication between the stakeholders, and established a faster, more transparent decision-making process.
No Room for Error
The 409-meter Bergünerstein Tunnel in Switzerland is one of many century-old tunnels requiring renovation over the next several decades to address problems caused by aging. The Rhaetian Railway contracted with Rhomberg to retrofit and enlarge the tunnel to meet current safety standards, and Rhomberg retained Donatsch to perform the necessary survey work based on Amberg’s design. Amberg created the tunnel design in Revit, a building information modeling software, and loaded the 3D model directly into Trimble Connect, providing access to all stakeholders.
As-built 3D-model of the existing, 120-year-old Bergünerstein Tunnel.
To undertake the extensive tunnel renovations efficiently, the Rhaetian Railway developed a new, standardized restoration method to improve quality, limit costs, and minimize operational disruptions. Throughout the two-year Bergünerstein project, trains continued to run during the day and all surveying and construction work was completed at night, between approximately 10 pm and 5 am. To meet the required 3 mm accuracy, the Donatsch survey team mapped the control points in the tunnel using a Trimble® S9 robotic total station with a Trimble TSC7 controller and Trimble Access™ software, while the Rhomberg construction team performed many of the repetitive tasks, such as set-out work, with a Trimble S6 total station and scanned each stage of the tunnel outburst with a Trimble X7 3D laser scanning system.
As-built model combined with the BIM model from the construction design team in Trimble Connect.
Laser scan of each stage captured by Rhomberg with a Trimble X7 scanning system.
Trimble Sync Manager™ provided the interface between Access and Connect, so measurements collected overnight were synced in the cloud and ready for the Donatsch office crew in the morning. The Trimble Connect cloud platform was a key part of the workflow, allowing data to be transmitted and made accessible to everyone at the same time.
Donatsch was responsible for calculating excavation and shotcrete volumes to show how much rock was removed and how much shotcrete had been added. Laser scan data was used to create profiles for over and under excavation analysis to ensure the tunnel was large enough for the train to pass, and as-built measurements were compared to the model to verify accuracy. By loading a colorized 3D point cloud into Trimble Connect, analysis showed if any work needed to be corrected (i.e., green is good, red is too deep, blue is too high, etc.).
In Trimble Connect, a colorized point cloud was compared to the design to identify areas that required rework.
As-built cross sections are measured by the construction company in the field using the Trimble Access Tunneling Module. The Tunnel As-Built Report can be exported directly from the controller.
The cloud process allowed Donatsch workers to check the results in a timely manner and quickly catch errors or identify gaps. For example, the construction crew once used the wrong target model on their S6 total station, so the measurements were incorrect. The error was caught the next day and fixed before any problems occurred.
“Trimble Connect enabled us to effectively communicate the survey work and progress with our contractors, shortening time to decision-making and increasing confidence that work was meeting specifications,” said Fadri Jecklin, Project Manager and member of the management board at Donatsch. “We received the data faster—it was ready when we arrived in the morning—and we downloaded the raw data and viewed it in Trimble Business Center to check control points and settings.”
Set-out points for the concrete precast elements of the railway were exported from the BIM model and used as an overlay in Trimble Access to view on the Trimble T10 tablet.
Donatsch also used the tunnel project to experiment with a model-based workflow by running tests on different kinds of set-out work. Set-out points for the concrete precast elements of the railway were exported from the BIM model and used as an overlay on the Trimble T10 tablet or the TSC7 Controller in Trimble Access. In the wet, dark, dirty and cold environment of a tunnel, working with a digital model on a rugged case tablet or controller instead of paper plans and drawings was more practical and convenient.
“Model-based workflows create a deep understanding about the project as a whole and support innovative ways of working,” said Jecklin. “The building model also provides additional possibilities for analysis and calculation, which is a big advantage.”
Parametric Tunnel Definition prepared with Trimble Business Center Tunneling module.
Harnessing the Power of Collaboration Tools for Expedited Decisions
Implementing a cloud-based workflow makes up-to-date information available to all stakeholders. The information collected in the field is synced with the office in near real time, so office workers can perform quality checks and calculations without delay. The coordination of all data in Trimble Connect supports early detection of planning and construction errors and helps meet stringent timelines.
“Trimble Sync Manager and Connect in the cloud provide the best model-based workflows, and we like Trimble’s open interfaces because they give us the flexibility to use the best hardware and software for each job without worrying about data compatibility between vendors,” said Jecklin. “Being a beta tester for the Trimble Tunneling group gives us the opportunity to provide feedback on performance. We benefit from many improvements that have streamlined our workflow in the past few years.”
On recent projects when Donatsch acted as a BIM Coordinator, Trimble Connect was used as a coordination tool and to share additional survey data about pipes, manholes, light poles and other objects. With the ability to upload native and all other kinds of file formats into Connect, comprehensive data was always available when needed, and calculations and analysis were easily disseminated.
“Using the cloud and Trimble Connect is standard practice on all our larger projects now. It is much more efficient than communicating through email and uploading data to Dropbox.” — Fadri Jecklin, Project Manager and Donatsch Management Board Member