The two tunnels are 2.1 kilometers (1.3 mi) long and they are part of the Granfoss Line, a 2.9-kilometer (1.8 mi) stretch of motorway which was opened in 1992 connecting Ring 3 with the European route E18.
The name comes from the Granfossen waterfall on the Lysakerelva river, which passes nearby.
When the two tunnels with four lanes were opened for traffic, a bottleneck of Oslo's road system which had lingered for several decades was finally dissolved.
The tunnels were financed by Oslo Package 1.
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