Developed checklist to identify cost drivers in the ground

-The method is working well, and we have received very positive feedback, says Magnus Tenge, Acting Director in the Department of Sustainability and Special Fields at Statsbygg.

He leads the sections in Statsbygg where the method is used by hired geotechnical engineers.

-Statsbygg uses the tool in the early phase and intends to use it in all our projects. We are in the early stages, so we are in the process of building internal knowledge and clarifying roles and responsibilities, says Tenge.

25 factors that can affect costs in underground works

NGI (Norwegian Geotechnical Institute) has assisted Statsbygg in developing the method and the TidligSøk tool, which allows for the identification of factors that can increase the costs of construction processes. NGI has identified 25 different factors that can all affect costs in underground works. These factors include contaminated soil, the risk of damaging neighboring buildings due to settlements, the need to redirect streams that are currently piped, and the need for piles or measures to stabilize quick clay.

-The purpose of the tool, and the process of using it, is to provide the stakeholders who assess one or more sites with a rough overview of the ground conditions at each location and to highlight any local issues that may contribute to economic uncertainty in the decision-making process. The tool also identifies any obvious deficiencies in the foundation that need to be addressed before choosing a concept. This will enable better and more equitable comparisons between different sites, says Gunvor Baardvik, Senior Specialist at NGI's Department of Environmental Geotechnics.

Good mapping tools provide basic knowledge for site selection

To develop the tool, NGI and Statsbygg reviewed several major projects to identify how ground conditions were considered in the earliest phases.

-Traditionally, conducting ground investigations is a good method for gaining knowledge of ground conditions, but it takes time and requires planning. Nowadays, there are many excellent mapping services that make it easier to access basic knowledge about a site before conducting ground investigations, says Baardvik, referring to mapping services provided by organizations such as the Norwegian Geological Survey (NGU), the Norwegian Water Resources and Energy Directorate (NVE), the Norwegian Mapping Authority (Kartverket), and the Norwegian Environment Agency (Miljødirektoratet).

-The tool is therefore a summary of the factors that can be the most costly to overlook. It also provides references to where one can find maps and data about the different factors. When all the information is gathered, one looks specifically at their project, evaluates each factor in turn, weighs them based on what they believe they will mean for costs in the specific project, and gives them a score from zero to three. Finally, a score is obtained for each factor. A high score means that one should expect significant costs related to the specific factor and that the factor should be further examined in the early phase of the project, says Baardvik.

Profitable method

Tenge from the Norwegian Directorate of Public Construction and Property mentions that some further adjustment and adaptation are needed to make the approach work for different types of projects. Moreover, the TidligSøk tool will be integrated with safety, health, and working environment aspects at Statsbygg. When asked if Statsbygg would recommend the construction industry to use the tool, Tenge is clear:

-Yes, the effort 'pays off' later in the project by providing better decision-making foundations.