The presence of a few vehicles from the Regional Emergency Action Coordinating Team, or REACT, a Maricopa County Department of Transportation program, is the only indication to passing motorists that something unusual might be going on.

In a few minutes, the specially equipped vehicles will be deployed as part of an exercise in connected-vehicle technology overseen by University of Arizona engineering professor Larry Head, who has been staging such field tests for about eight years — but working on the infrastructure for vehicle-to-vehicle communication, or V2V, for much longer.