Innovative construction strategy reduces CO2 and overcomes swamp obstacles

^{*Image courtesy of COWI}

The Norwegian Public Roads Administration has contracted Hæhre-Isachsen and COWI to construct a new four-lane motorway called Highway 4. The project aims to increase capacity and reduce Roa ‑Gran stretch accidents. 

The budget for the project is over NOK 700 million, and construction started in September 2021, with an opening date set for November 2023. A cutting-edge road construction method aims to reduce CO2 emissions by over 30%.

Navigating environmental hurdles and quick clay

Constructing a four-lane highway on Highway 4, which connects the municipalities of Roa and Gran in Norway, posed multiple difficulties. The first challenge was figuring out how to build the highway through a swampy area without causing any damage to the natural habitat. Another concern was the presence of quick clay in the ground, which is known to liquefy and collapse under pressure. Lastly, an essential project requirement was ensuring the construction process has a limited carbon footprint.

As the company responsible for the engineering, COWI realized that geotechnics would be laying the framework for the job. The demands of the ground conditions would limit the possibility of execution. 

“We stabilized the swamp area with a special geotechnical solution, for which we were dependent on close cooperation between the geotechnicians and construction teams. This solution has been the key to success on the project.” 
Frode Geir Bjørvik, Project Director, COWI

^{*Image courtesy of COWI}

Model-based cooperation across borders

To tackle the challenge, an interdisciplinary team was set up across national borders: COWI’s Danish geotechnicians in Ålborg were responsible for investigating the ground conditions. The team responsible for structures was located in Trondheim, Oslo, and Kristiansand, Norway. 

On the project, Trimble Quadri was used as a collaboration solution by both the designer and the team from contractor Hæhre-Isachsen on the execution side. 

“Quadri is a fantastic tool for us. The model-based way of working also makes internal collaboration easier. Having the design model in Quadri facilitated the work of finding the right solutions and making adjustments along the way. This is particularly valuable when you choose a non-traditional approach, as we did in this case.”

Frode Geir Bjørvik, Project Director, COWI

Innovative construction approach slashes CO2 emissions

Overall, the biggest challenge was to put in the foundations for the bridges and roadway. Instead of replacing the swamp masses or constructing a larger bridge over the swamp area, a network of around 2,000 lime cement columns was created to stabilize the soil. Even if the solution is invisible, it still provides a stable surface for the road. The solution also helped reduce CO2 emissions by more than 30 percent compared to traditional road construction. 

^{*Image courtesy of COWI}

“It’s been important for us to find ways of working that ensure that we have secure interfaces, between technologies and people. Due to the varying ground conditions, geotechnics must be the starting point. Those teams deliver data as input for the structural engineers so they can start the process of finding out what is optimal in terms of cost, CO2 emissions, and health & safety.”

Frode Geir Bjørvik, Project Director, COWI

The various layers in the ground were modeled in Quadri, which in turn were based on ground investigations analyzed in Trimble Geosuite in which the depth and material of the ground condition layers were mapped. This data was then combined with previously acquired data from superficial deposit maps and other investigations in order to create a complete model of the ground conditions. The geotechnicians interpreted the results to determine the mass type in the various layers. This information was then entered into the model. 

“It’s important to maintain control over any high-risk zone where we can dig so that the ground does not collapse, etc. This is crucial information for the contractor when considering mass replacement. They also need to know where stabilization of the swamp is needed before work commences,” Bjørvik elaborates.

Simultaneous design and build, using a common platform

Already in an early stage, the geotechnicians shared their models with the bridge and road engineers. Civil engineer for bridges at COWI, Audun Øvstebø, believes that the ability to work in parallel and make rapid adjustments have been the true success factors in the implementation of the project.

“By establishing the conceptual design quickly, it’s easier to see the challenges you will be facing in the execution and in what order you should address them. We already had conceptual models in the tendering phase during which we considered multiple solutions, especially for tackling the geotechnical challenges. What we came up with has proven to be feasible, and it has worked very well in practice.”

Frode Geir Bjørvik, Project Director, COWI

Trimble Quadri and Tekla Structures have software connectors for the widely used parametric design tool Grasshopper 3D. Tekla models can be updated parametrically from Grasshopper based on updated road geometry from Quadri. “If, for example, due to geotechnical conditions, you need to add two extra columns, and the ten that were already planned around those two are to be repositioned, there’s no problem adding those new ones. Changes from geotechnics are incorporated immediately, and then these can lead to new analyses that are communicated back,” he continues. “The common understanding of what is going on is important when there are many changes taking place close to delivery. Working simultaneously on the design while construction is happening requires that the models need to be clearly marked with the Model Maturity level that they have reached.”

^{*Image courtesy of COWI}

Detailed and solution-oriented

The geotechnical models in Quadri have established the basis for all technical decisions. “The models have made it easier to stay in control and have been of great help to the engineers when it comes to stake-out data and progress planning,” says geotechnician Kenneth Christiansen. This is the first project where the Ålborg office of COWI has provided such detailed information about the ground conditions into the model. Instead of delivering a stack of drawings, the geotechnicians at Highway 4 delivered everything in Quadri. It ensures a common understanding that’s not as easy to achieve working the traditional way. 

“We’ve also shared our thoughts about the design with the contractor to get immediate input on its feasibility and to get an idea of whether it might be possible to do certain aspects easier and faster. If something has to be moved because a structure or a road has changed, then there is a continuous process in place to consider all variables,”

Kristoffer Lauridsen, Project's geotechnician

For example, a culvert project was found to break the zoning plan, but the road was successfully relocated onto a bridge to avoid consequences. The early discovery allowed for efficient plan changes and the involvement of geotechnicians in determining the cement ratio for stabilizing the swamp area. This discovery prevented any negative impact on the overall progress of the project.

Efficient workflow from design to field

COWI and contractor Hæhre-Isachsen collaborated using the Quadri model environment from the tendering phase onwards. The Norwegian Public Roads Administration had access to updated models through a separate model viewer. Stake-out data was obtained from the collaboration model and delivered in the IFC file format, which the contractor used Trimble Connect to retrieve for the structures.

The industry has had difficulty ensuring that field workers using models on tablets receive necessary information, such as measurement annotations. COWI used Trimble Connect's API to automatically calculate deviations and add measurement annotations on the Highway 4 project. They plan to further develop this feature in their next project, making the models more suitable for use by construction workers and reducing manual work.

More rewarding working days

The use of model-based engineering in the construction of the Highway 4 project has led to a more rewarding working day for employees. This process eliminates routine work and allows for the reuse of knowledge. Additionally, model-based engineering has increased knowledge about constructability, progress, and cost, leading to nontraditional solutions and an early completion of the project.