This November 2017 photo shows a new "Wrong Way" sign on an overpass along Interstate 17 in Phoenix. Large new overhead signs have been placed on Interstate 17 bridges in Phoenix to warn drivers going the wrong direction. (Arizona Department of Transportation via AP)
In January, Arizona began testing a system to both prevent and warn about wrong-way driving on a main stretch of highway there.
Here & Now's Robin Young speaks with state engineer Dallas Hammit about how the system works.
