MoDOT is using a new enhanced pedestrian crossing system at locations across the state. The new crossings make it easier for pedestrians to safely get across busy roads at locations that are not at signalized intersections. It also minimizes traffic delays, because it only operates when a pedestrian activates it.
Next, two red lights will be displayed, requiring cars to stop. After a few seconds, the red lights will alternately flash indicating that drivers may proceed after stopping IF there are no pedestrians in their lane.
When pedestrians are not present, the lights will not be on and drivers can proceed without stopping. Check out the diagram below describing the sequence seen by the motorists and the corresponding messages seen by the pedestrians.