Update at 3:15 p.m.: All lanes are now reported to be back open.
Arlington police are preparing to close Jefferson Davis Highway (Route 1) at the Reagan National Airport overpass, near Crystal City, due to a report of a downed power line.
Firefighters are on the scene and requested the busy artery be closed in both directions, according to scanner traffic.
No word yet on how long the road will be closed.
For the hundreds of thousands of migrants on the move across Europe, the pace of a day is dictated by forces almost entirely beyond their control.