North American updateThe proposed replacement of the Alaskan Way viaduct in downtown Seattle with a 3.2 km-long bored double-deck road tunnel is symptomatic of the current trend in North America to take potential problems underground. The reality is that tunnels are more environmentally friendly and less visible than viaducts, and that their construction is less intrusive, making them more likely to be approved and built, especially with USD500 billion of economic stimulus funding being made available for new spending read more. 08/09.