Wig-wag signals were commonly used in the middle of the last century for warnings at grade crossing.  They included a lighted target or banner which moved from left to right in operation.  Many also had bells.  Very few remain in operation today.  Operational wig-wags like the one at right can be seen in Northern California at the Tilden Park steam train located in the Berkeley hills and on the Niles Canyon excursion railroad which departs from Sunol.

Photos are limited due to the fact that I do not own one.  If you know of any that are available for purchase, please email me.

For detailed wig-wag information see Dan’s Wig-wag search