The Washington State Department of Transportation (WSDOT) in the US is planning some key changes on the ageing State Route 520 floating bridge.

The agency plans to hire a contractor to build a new floating bridge across Lake Washington, a project estimated at $700m-$900m.

Other works planned include Eastside highway construction, building 33 floating-bridge pontoons in Grays Harbor for the new bridge, and interchange and HOV upgrades by next year.

The current bridge will also be installed with new Smarter Highways signs, which provide real-time traffic information, variable speed limits and lane status indicators to alert drivers of approaching congestion, collisions and blocked lanes.

Electronic tolling, to be implemented in 2011, is intended ease traffic flow and help fund a replacement for the old bridge.