Trafikverket (The Swedish Transport Administration) is responsible for the long-term planning, building, operating and maintenance of the Swedish transport system. (www.trafikverket.se)
Ramböll is an engineering, design and consultancy company founded in Denmark and works within the areas of Buildings, Transport, Environment and Health, Water, Energy, Oil & Gas, and Management Consulting (www.ramboll.com)
We would like to thank Trafikverket & Ramböll AB for allowing Guideline Geo to use information, illustrations, photos etc. from their pre-investigations of the re-routing of the E22 highway.
N.B The geophysical investigations were correlated with existing geotechnical drilling logs. The resistivity survey was not the only source of data for the final geological interpretation.
Due to the increased traffic intensity on the E22 highway and limited possibilities to broaden the road, a new solution needed to be drawn up to ensure the flow, safety and environmental values. A large aquifer in the area supplied the surrounding municipalities with drinking water which needed to be dealt with carefully. Protecting of the groundwater and finding the most efficient solution was in focus.
A subsurface mapping of the 11.5 km road stretch was made with the resistivity system ABEM Terrameter LS with 4×21 cable system. The roll-along methodology was used in order to create a long profile with the 400 meter long cable. Aarhus Workbench was used for the data processing. To acquire more information about the geological conditions, partial parallel profiles were also created to improve the basis for decision. D-GPS was used to measure the topography along the profile.
The outcome of the mapping of the subsurface resulted in positive results from both a financial as well as environmental perspective. The survey showed that a thick clay layer above the bedrock would act as protection for the underlying aquifer. For most parts of the 16 km potential road section, no additional protection was required. The outcome and analysis of the survey delimited the need for water protection work. The monetary saving was estimated to 50 MSEK ($5.6) together with the environmental savings.