Excerpt:
There are three basic types of movable bridges; the bascule, the vertical lift and the swing bridge. Multnomah County operates four movable bridges; one vertical lift and three bascule. The purpose of the following pages is to provide information on how Multnomah County operates these bridges and the distinguishing features of each type.
...Bascule bridges have sections that rotate upward and away from the centerline of the river, providing clear passage for river traffic. Side-by-side on the Willamette River in downtown Portland, the Morrison (left) and Burnside (right) bridges are two examples of bascule bridges. These two bascule type bridges have a very clean, uncluttered look to them because the counterweights and operating machinery are located out of sight in the piers supporting the bridge. The Morrison Bridge is a Chicago-type bascule bridge and the Burnside Bridge is a Strauss-type bascule bridge. Please refer to our pages titled Operation of a Chicago type Bascule Bridge and Operation of a Strauss type Bascule Bridge for a discussion on the workings of these types of bridges.
Annotation:
Description of the operating techniques of the Burnside Bridge lift span designed by Joseph Strauss.