Länsimetro is the infra project of all times in Finland
Länsimetro will combine Espoo to Helsinki metro line. The enormous project includes pumping stations, track shifting locations, over 30 km of parallel tunnels and 8 new stations (150 000 brm2), each with its own identity to help passengers navigate underground. The final budget exceeds billion euros.
The massive project required long and throughout design, which A-Insinöörit started already in 2009. In addition to the size, the challenging circumstances brought on extra spices since the line is located in a challenging rock surrounding and largely below sea and groundwater level. From the beginning it was clear that BIM was needed to manage the challenges and diversity of the underground stations. The bulk of structural design was carried out with Tekla Structures, with versions 15, 16, 17, 18 and 19. The architects used several different software and MEP designer Granlund used MagiCAD.
Structural modeling had to take both the architectural complexity and the challenging and massive structures into account. The varying shape and kind of rock, splits in rock, structural density and restraint actions all mattered because all the structures were both limited and anchored to the rock. The environment was structurally very challenging, and, therefore, new structural solutions and details were created to match both Länsimetro and Eurocode requirements.
One example of great structural and modeling successes in this project was the wooden rail roof of Koivusaari station. Several phases of modeling and use of different software was required to achieve the wanted result. The surface model of the double-curving roof plywood sheets was created with Rhinoceros, where beam geometry was imported in IFC format as initial data. Accurate factory drawings were created from the surface model. Dimensioning and finning data was added with AutoCAD, and the sheets were cut to correct sizes. The end results were accurate part drawings that followed the curving surface - a results that hardly achievable with any other method.
Later the timber structures above the roof were modeled with Tekla for the site. The imported roof studding from Rhinocero for Tekla was converted to polyline with sections defined in Rhinocero. Thus, the created reference model is as useful in Tekla as a native geometry.
New modeling tools
Available Tekla components were very much used in the project, but the scale and special circumstances required also new tools. For instance, in precast concrete detailing for shafts and stations a new plug-in that creates fastenings for erection supports were created by A-Insinöörit.
A larger tool set was created for modeling retaining wall elements and valley elements. To increase efficiency, retaining wall elements and gullies on the rail line were modeled as components. There were several kilometers of retaining wall elements and a gap of 5 mm in between was required. This problem was solved with a retaining wall tool, which created the retaining wall automatically on the specific rail line. Also the attached valley elements were modeled with this tool. Later a model point tool was created to automatically create coordinate points for selected retaining walls. This helped to create reports of element coordinates.
Versatile model use
BIM has been put to good use. Designers have benefited a great deal by using the model to interpret the combination of the complex structures that criss-cross on different levels and the design data from other designers. With BIM, communication is efficient and solution driven. Structural models played a major role on stations, where the architect did not use modeling. BIM was not required nor defined by the owner, and thus, the process was refined between the designers and site. The cooperation functioned surprisingly well.
The 3D data of the rock surface was imported to the models for reference. With a comprehensive data of rock surface the structures were made to fit the rock surface topography, the concrete and steel quantities were estimated more precisely and the anchoring of the structures to the rock surface was easier to design. The reference model of the rock surface was also utilized in the drawings, because sketching the uneven rock surface to different drawings would otherwise have been very difficult.
In addition to the designers and site, the information in the models was used e.g. in demonstrating the designs to the authorities. Lauttasaari and Koivusaari were presented to Helsinki building authority solely with BIM. Model data has been delivered from precast concrete detailing to production planning and production control system e.g. at Destia and Parma. Data of design status was imported to Parma’s production control system.
The BIM models were made available also for the general contractor for planning and controlling production. The models were utilized at site e.g. for visualizations and inspecting complex structures and reinforcements. Quantity information in the model was used for bidding subcontracts. On some sites, scheduling and follow-up was model based.
The cast in place contractor and the form provider have also used BIM. The contractor of steel structures at Tapiola station has used the rock model and combined his steel structures to that, which enabled producing the parts in the shop with exactly right dimensions.
Structural design and precast concrete detailing: A-Insinöörit Suunnittelu Oy
Precast concrete detailing: Ramboll Finland Oy
Architect (Otaniemi, Keilaniemi stations): Arkkitehtitoimisto ALA Oy
Architect (Koivusaari, Lauttasaari stations): Arkkitehtitoimisto Pekka Helin & Co Oy
Architect (Matinkylä, Urheilupuisto, Niittykumpu stations): Arkkitehtitoimisto HKP Oy
MEP design: Granlund Oy
General contractor (Otaniemi station, Urheilupuisto-Matinkylä tunnel): YIT Rakennus Oy
General contractor (Matinkylä, Niittykumpu, Tapiola stations): Lemminkäinen Infra Oy