The Brownsville and Matamoros Bridge Co. was combination road, rail truss bridge across the Rio Grande at Brownsville, Texas with the MP/UP connection to Mexico across it. There was a guard that would come out and stop road traffic to let trains across.
So it was a road bridge, a train bridge, an interchange and an international border, al rolled into one. It has since been converted to an all rail bridge and a rail new connection outside town was built.