The solution was to build a cleaning plant in a 300 - foot - long [100 m] parallel tunnel six miles [9.5 km] from the Aurland opening. At both ends, this tunnel is connected with the main tunnel.
Deviņarpus kilometrus no tuneļa Aurlandes gala celtnieki uzbūvēja 100 metru garu paralēlu tuneli, kurš abos galos savienojas ar galveno tuneli un kurā tika izvietotas gaisa attīrīšanas iekārtas.