The Oregon Department of Transportation is advising travelers to frequently check road conditions and use extreme caution or delay travel plans altogether.   ODOT crews, working 12-hour shifts, have applied deicer along all lanes of Interstate 84 between Hood River and Troutdale.   Other roads treated with deicer include U.S. Highway 26, and Oregon Highways  224/212 and 211.  In addition, an I-84 maintenance project between mileposts 51 and 56 has been postponed.  The project would have closed one lane in both directions.  Maintenance crews will be checking I-84 and other roads Tuesday night.