Drivers who use the Hood River–White Salmon Bridge should prepare for several overnight closures beginning in mid-August.  The Hood River–White Salmon Bridge Authority says the closures are needed for geotechnical exploration near the Washington shoreline as part of the Bridge Replacement Project.  Crews will lower drilling equipment from the existing bridge, complete the testing, and then retrieve the equipment using a process designed to protect the bridge.  The Port of Hood River says the bridge will be closed from 11:30 p.m. until 5:00 a.m. August 17th through the 19th, August 26th and 27th, August 31st through September 3rd, and September 8th through the 10th. The final closure in each window will end at 5:00 the following morning.  Officials say the work could be finished sooner than expected, so not all scheduled closure nights may be needed.  Motorists are encouraged to plan ahead and use an alternate route during the overnight closure periods.