By Peter Samuel
TUNNELS & TUNNELING INT magazine (11/00 p24) lists eight road tunnels in preliminary or detailed design in Hong Kong. They total some 29km (18mi) in length ranging between 0.9km (3420') and 4km (2.5mi) and all but one are being excavated to 16.3m (53') wide by 10.9m (36') so they provide space for 3-lanes. All the proposed tunnels are twin tube for 3-lanes each direction large by comparison with typical rail transit tunnels which tend to be 6.5m (21') diameter for a single track. Granite is the commonest tunneling medium but there are also fractured volcanic tuffs, rhyolite and some soft ground. Most of these are being built and financed by concessionaires who levy tolls to service the investment.