SR 520 pontoon construction to begin next month

The new 520 bridge is moving ahead on a new front with construction set to start in mid-February to produce massive concrete pontoons for the floating bridge.

The project, in Aberdeen, is expected to hundreds of workers.

Plans to build the SR 520 Pontoon Construction Project at the Aberdeen Log Yard gained federal approval this week, clearing the Washington State Department of Transportation (WSDOT) and Kiewit-General Joint Venture to begin final design on the project, obtain permits and then start construction.

In the months ahead, crews will build a casting basin facility that will turn out 33 concrete pontoons up to 360 feet long each.

The existing bridge opened in 1963 and is vulnerable to strong wind and waves. In the event of catastrophic failure, the pontoons built in Aberdeen could be used for emergency replacement. If not needed in an emergency, the pontoons can be stored and used for a new six-lane SR 520 floating bridge, proposed to open to traffic by the end of 2014.

WSDOT awarded the $367 million construction contract to Kiewit-General in January 2010. The planned pontoon casting basin will be large enough to produce six pontoons per cycle – four full-size pontoons and two smaller supplemental pontoons. The 33 pontoons include:

· 21 longitudinal pontoons measuring 360 feet long, 75 feet wide and 29 feet tall.

· Two shorter cross pontoons, each 240 feet long, 75 feet wide and 34 to 35 feet tall.

· 10 supplemental stability pontoons measuring 98 feet long, 60 feet wide and 29 feet tall.

The pontoon construction project is funded in part by future revenue from tolling that is scheduled to begin on the floating bridge in the spring. The state Legislature set the SR 520 program budget at $4.65 billion for improvements from I-5 in Seattle to SR 202 in Redmond. Toll revenue along with state and federal funds provide about $2.37 billion for the SR 520 improvements. WSDOT will continue working with the lawmakers to identify additional funding for more improvements in the corridor.

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