Norway's long cheap tunnels
The Norwegians are world champion tunnelers. They build road tunnels longer and cheaper than anyone else, mostly with a system of investor owned toll tunnel concessions, sometimes with government subsidies. Norway is large and very rugged, the population modest (4m) so traffic is light. Most of the tunnels are single tube, one lane each way, jetfan ventilation, often with bare rock lining no frills holes. But they work.
Excavation is nearing completion on the Laerdal Tunnel, the worlds longest road tunnel apparently at 24.5km (15mi). It is on the E16, located about 150km (90mi) east of Bergen on the highway to Oslo. 20mins or so in the new tunnel will replace a mountainous section of the road that takes over an hour and is often closed in the winter. Theres another existing long tunnel on the same road the Gudvanga 11.4km (7mi).
The St Gotthard tunnel in the Swiss Alps on the N2, a major route between Germany and Italy, is generally credited with being the longest vehicular tunnel presently operating at 16.9km (10.3mi). The Mont Blanc Tunnel between France and Italy, presently closed following the terrible fire of last year is 11.6km (7.2mi). The Tokyo Bay tunnel is 10km (6mi), as is the planned doubledecker light vehicles tunnel on the A86 outer beltway around Paris.
Melbournes Burnley tunnel on the CityLink due to open shortly is 3.6km (2mi) about the same length as the Oresund tunnel being built under the main Baltic Sea shipping channel between Denmark and Sweden.
The US is in the minor leagues when it comes to road tunnel lengths, the longest still being the 1950-opening Brooklyn-Battery tunnel in NYC at 2.8km (1.7mi) and the Eisenhower in the Rockies on I-70 2.7km (1.7mi). But the Fort McHenry Baltimore harbor tunnel is, we think, the fattest (8-lanes) though the Germans in Hamburg with a fourth 14m tube under construction at the Elbe threaten to take that honor from us.
But the most extraordinary feat of the Norwegians is their low tunnel costs. The Laerdal will cost $130m, just $2.5m/lane-km ($4m/lane-mi.) Other tunnels are regularly built in Norway for $3m to $4m/lane-km. In California or Washington DC the environmental studies and public hearings would cost that much before a bucketful of muck was moved. Well nearly. Urban surface road in the US usually costs in the range $2m to $7m/lane-km. A 2.3km tunnel under the Potomac R to replace the Wilson bridge was costed at $75m/lane-km (though that was a costing by bridge enthusiasts!) Bostons Central Artery usually regarded as one of the worlds most extravagent bit of undergrounding rings in at $42m/lane-km, while the I-710 Passadena CA missing link is costed at $17m/lane-km, about the same as the new Wilson bridge project (including approaches) as a bridge.