Anna Fredriksson, Linköping University, and Pamela Nolz, Austrian Institute of Technology have looked at optimizing construction logistics, with the Ostlänken project as an example, by using an optimizing tool, created by Pamela Nolz and her colleagues.
“It all starts with the land expropriation law. In Sweden we are not allowed to use more land than we can justify when building infrastructure due to the land expropriation law. The Swedish Transport Administration are very early in the process looking into the land expropriation, but the question is then how can they know how much land they will need during the building process? This is closely related to how much material that needs to be stored during a building process such as mud, gravel and rocks,” explains Anna Fredriksson.
“Anna and I have therefore with our different backgrounds and knowledge investigated how the construction contractor should manage the logistics in a better way,” Pamela Nolz explains.
“The first questions that need to be asked are where these enormous amounts of masses should be located; how and when should it be transported during the project?” Anna Fredriksson continues.
Today the construction contractors are planning the logistics but, in most cases, they have not investigated the relationship between the amounts of masses, how much land they need, the location of the land and how many transports there will be.
“I want to enhance the importance in that the construction contractors understand the interconnection between different decisions that they make during the duration of the construction project,” Pamela Nolz says.
The optimization method
“We at the Austrian Institute of Technology, have created a decision support for the construction contractors that they can use. With this method we want to show them that each decision influences another decision and therefore another part of the logistics chain. With this model we will provide different solutions to them and visualise the impact of the decision and how it will impact the next step and/or decision. This model that we have created is not disposable, it can be used in many ways and can be fed all types of data. You can change the parameters in the way you like. It can both be a tool to plan, but also a tool to test and show how one decision can impact another one further on in the logistics process,” Pamela Nolz continues.
Pamela describes how Anna and herself then applied data from a stretch of Ostlänken (close to Norrköping) into the tool to see how it could improve the construction logistics in this project.
“We started by adding data that they had since before into the tool, which was very useful. The questions that we had were: How do they do it right now? What amount of rock and earth masses do they excavate today? What kind of vehicles were used? And to where was the material transported? “
“Together we then looked at places along this stretch that could be used as storage points, but also what vehicles that would be best to use to be as effective as possible. We looked at different scenarios with different choices of vehicles and storage points that could be interesting to the decision makers within the construction contractors.”
“We also looked at the entire process from when it was excavated to whether it needed to be stored immediately or that it should reach its final point such as landfill at another location. In the Ostlänken project it is the same cost of using one piece of land one day or 300 days so what we did was looking into avoiding peaks. One of our findings was therefore that they should not start excavating at the same time at different locations because then you will have a lot of material that needs to be transported at the same time. If you start excavating at one point earlier than on another point, you can both use the second point as a storage point first but also use the same vehicle but at different times,” Pamela Nolz says.
With this Optimization method the construction contractors can in a very sophisticated way change how different times, locations and vehicles can affect their work in a positive direction.
“Our goal is always to minimise the storage- and transport costs. In the end this is also the most sustainable solution, so it is a gain for everyone, both the climate and the developer’s wallet,” Anna Fredriksson concludes.