The bridge was built in 1915 to connect the North Western Railway to the Mainland of England. Many engines cross over the bridge everyday to transport passengers and goods from Sodor the the Mainland or vise-versa.
Caitlin attempted to return to the Mainland, but Andy crossed over the bridge and knocked her off the rails. Hiro tried to stop Andy, but the latter knocked him into the river below. Off-screen, the Flying Scotsman used the bridge to travel to Sodor and from Sodor with Gordon.
Later, the Mastermind asked 089 to travel to the bridge and meet his comrade, Gerard. He did so, leaving Lady, Winston and Sir Stephen Topham Hatt behind. Lady eventually crossed the bridge off-screen so she could reunite with 089.
The latter mentioned event will occur in The Road to Sodor.