When Gilbert acquired American Flyer in 1938, they introduced Gilbert designed accessories to compliment the train line. The first Gilbert American Flyer design bridges used Gilbert Erector Set Gilbert AF 1st Bridgeparts. The migration of parts went the other way as well. The house at the top of an American Flyer signal tower became the Erector Set house.
Gilbert American Flyer Crossing Gates were introduced in the pre war 3/16’s product line from 1938 to 1941. Many of the parts that were in inventory when toy production was stopped for the war were saved and then used in the post war products. The first crossing gate introduced in the post war period was the 591 which continued the prewar 591 design but with the wiring adapted to the newly introduced two rail track system.