The Sydney Harbour Bridge is a through arch bridge which uses a truss type arch. Each main span consists of two cantilever arms supporting a central span truss. The bridge is the only cantilevered deck truss in Oregon. This is accomplished by using metal ties fastened to each rafter or truss. A large truss measuring spans the roof. Early wooden bridges were usually of the Towne lattice truss or Burr truss design. An example of a camelback truss is the Woolsey Bridge near Woolsey, Arkansas. This is a three-lane through truss bridge. Hannay then escapes, hiding behind the bridge's truss. An example of a Parker truss is the Traffic Bridge in Saskatoon, Canada. The Union Pacific also utilized their experience repairing and building truss bridges during the war. A combination of the two is a truncated truss, used in hip roof construction. Bridges are the most widely known examples of truss use. Alongside the main horizontal truss are two retractable columns. This list includes bridges that act primarily as a continuous truss.