Aside from cost, what are the downsides of tunnels? How about advantages?
The website of The Automobile Association Limited of England has the following list of tunnel downsides: • Higher building costs and difficulties of cost control during construction • “cut and cover” tunnels can be disruptive during construction • good standards of daily operations required • ongoing operational costs • underground junctions difficult and potentially expensive • siting of portals and ventilation shafts needs to be carefully selected There are probably other disadvantages to urban tunnels not included on their list. Examples are safety issues – emergency vehicle access, fire protection, emergency egress, and perhaps claustrophobia issues for some motorists. Their website also has a list of advantages to tunnels. Here are a few of my favorites: • while vehicle emissions on surface streets flow straight into the air, harmful pollutants in tunnels can now be collected before ventilation and “scrubbed” near clean using new technologies • techniques of tunnel construction ha
