Extreme Engineering : A bridge across the Bering Strait

The concept of an overland connection crossing the Bering Strait goes back at least a century. The route would lie just south of the Arctic Circle, subject to long, dark winters and extreme weather (average winter lows −20°C with possible lows approaching −50°C.). Winter maintenance of any exposed roadway would be difficult and closures frequent. Even maintenance of enclosed roadways and pipelines could also be affected by winter weather.

According to Discovery Channel the Bering Strait could be spanned by a series of three bridges via the Diomede Islands for a total distance of about 80 km (50 miles). The two long spans would be comparable in length to the Lake Pontchartrain Causeway, the current longest bridge.

Ice breakup after each winter is violent and would destroy normal bridge piers, so the 55-mile-long bridge would need 220 piers, cone-shaped to resemble and function like the bow of an icebreaker ship, and weighing 50,000 tons each. The bridge would require thousands of kilometers of new road and/or track over extremely harsh terrain through the wilderness of Alaska and Siberia.

The bridge as envisioned would be three stories: the top for vehicle traffic, the middle for high-speed trains, and the bottom for oil and gas pipelines. The top would be open to cars and trucks only during summer months.

Discovery Channel's Extreme Engineering estimates the cost of a highway, double track rail and pipelines, including continuations on land, at $105 billion. This excludes the cost of new roads and railways to reach the bridge. There have been long discussions about a highway for the benefit of residents in western Alaska, but environmental concerns and fears of undue cultural influence from a higher number of visitors to Eskimo villages have obstructed these plans.


source : http://fogonazos.blogspot.com/2007/07/extreme-engineering-bridge-across.html