The Gothenburg Port Line Project-Paper

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The Gothenburg Port Line is being expanded from a single track to double track to accommodate growing freight traffic to the city’s harbor. This paper focuses on the Eriksberg–Pölsebo section, which includes tunnels through crystalline bedrock and soil. Protecting nearby groundwater, buildings, and natural areas is a key concern; the allowable inflow target is as low as 5 L/min per 100 m.<br /><br />The study describes grouting works in the Bratteråsberget transport tunnel, a smaller tunnel than the planned railway tunnels. The rock is generally good-quality gneiss and granite, with a dispersed fracture system and no major water-bearing fracture zones identified. Hydraulic testing showed that estimated conductivity varies with test scale, so large-scale borehole measurements were used for leakage calculations.<br /><br />The grouting design uses cement grout and a base layout of overlapping borehole fans. Investigation holes and water-pressure tests guide the choice of grouting class: one round is used where conditions permit, with additional holes or a second round planned for areas with higher inflow risk, low rock cover, or nearby infrastructure. Grouting duration and pressure are controlled, with limits on grout volume.<br /><br />Results from the transport tunnel have been encouraging. Grout consumption was generally low, and measured groundwater inflow reached only 0.3 L/min—well below the 10 L/min tunnel limit, equivalent to 5 L/min per 100 m. No lowering of surrounding groundwater levels was observed. The findings support the geological prognosis and indicate that the grouting approach is effective. The authors recommend continuing to use water-pressure tests and adapting borehole geometry to local conditions as work progresses, particularly in the larger and more challenging track tunnels.

Keywords

Gothenburg Port Line

double track expansion

grouting works

groundwater protection

tunnel leakage

crystalline bedrock

water-pressure tests

cement grout

Eriksberg-Pölsebo section

freight railway tunnels