Motorists traveling Interstate 84 near The Dalles should be aware of “rolling slowdowns” that may affect their drive.  As part of a contract with the Bonneville Power Administration, Western Construction crews are using helicopter airlifts to haul transmission lines from the Washington side of the Columbia River to the Oregon side at the Celilo substation adjacent to Highway 97 in The Dalles.  The rolling slowdowns, near the Celilo railroad bridge, are orchestrated to keep the highway clear while helicopter operations take place overhead.  These operations will continue on an intermittent basis, daily except on Fridays, from about 9 a.m. to about 5 p.m. into the month of July.  Operations on Sundays will be from about 7 a.m. until about 3 p.m.   Motorists are advised to drive with caution in the area and be aware of traffic control operations.