A crane lowering equipment for soil testing near the State Route 520 floating bridge might distract drivers and cause delays from 10 a.m. to 4 p.m. Tuesday.

Crews are scheduled to lower and assemble a barge and drill rig from an unused SR 520 ramp next to the westbound off-ramp to Montlake Boulevard. The equipment will be used to drill into the lakebed and shoreline to test the below-ground conditions for bridge design work. Up to 35 borings ranging in depth from 120 feet to more than 150 feet are planned in the Union Bay and Arboretum areas, as well as additional borings east of Foster Island and in Portage Bay.

The results of this and other geotechnical fieldwork will provide valuable information to WSDOT engineers and potential contractors as the state moves closer to construction. The information will be included in the environmental documentation for the SR 520 project from I-5 to Medina that will be released in spring 2011.