The bridge looks similar to The River Bridge and the bridge over The Little Western Extension line. It is gray metal supported by wood supports. On the top is narrow gauge track. Below it is the Standard Gauge main line.
Steadfast Overpass is a large steel bridge near Crovan's Gate. During a Tornado that struck Sodor, the supports were damaged and had to be repaired with the assistance of Kelly, Rosie, and Sodor Logging Co. Rusty had an accident on the bridge and almost crashed to the ground with the damaged bridge, but with the combined help of Rosie and Skarloey no one was harmed in the accident!
Nowadays, the bridge is safe and sound, and as "steadfast" as it will ever be!