Slideshow: The Plan for the New State Route 520 Bridge

Construction on the new State Route 520 Bridge will move to Lake Washington this week as construction crews move barges and heavy equipment next to the bridge, the Washington State Department of Transportation announced.

WSDOT has renderings of the future SR 520 floating bridge on its Flikr page.

The latest construction plans by contracting group Kiewit/General/Mason puts six lanes on the new structure, a 70-foot clearance underneath the bridge, which will eliminate the need for a drawspan, and a 14-foot-wide bike and pedestrian path on the bridge.

The bridge is part of the state's  from Seattle to Redmond and which .

So far, the state has identified tolls and federal and state gas taxes to fund $2.43 billion of the project, which includes the bridge construction. The state continues to seek funding for and is currently designing the bridge's connection to Interstate 5 through Seattle, which will be completed under a separate project, officials said.

"Starting floating bridge construction on Lake Washington is a huge milestone 15 years in the making," state Transportation Secretary Paula Hammond said in a statement. "Crews will build a stronger, more reliable floating bridge—and designs show the integrated architectural features will be distinctive and memorable for generations to come."

Along with bus and carpool lanes in each direction, five public viewpoints will be built along the path, and four lighted columnlike sentinels will mark where the new bridge transitions between land and water. 

The existing State Route 520 floating bridge was originally built in 1963.

The existing bridge has a drawspan which is fragile enough to necessitate closure during windstorms, and water from Lake Washington sprays onto the deck and cars during strong storms, said John White, the Department of Transportation official in charge of the new bridge's design.

The new bridge has been designed to withstand strong winds, will be higher than the "spray zone" and will not need a drawspan, White said, which will mean fewer expected closures due to storms.

The new bridge has been designed for 75 years, though it could last longer than that, White said.

Later this summer, the first batch of 77 huge floating concrete bridge pontoons will arrive by barge and tug, officials said. The pontoons, the biggest of which are larger than some buildings, were built in Aberdeen, Tacoma and Kenmore.

"We have an aggressive schedule, and contractor crews have more than two years of challenging work ahead of them at multiple work sites around the region," said Julie Meredith, WSDOT SR 520 program director.

Details about the new SR 520 can be found at www.wsdot.wa.gov/projects/sr520bridge.