We studied the Burnside Bascule Bridge yesterday. The Morrison Bridge is also a bascule bridge, which means the center leaf spans meet at midspan and swing up and down with the help of motors and counterweights (behind the pivot point). The Hawthorne Bridge is the oldest vertical lift bridge still in operation in the United States. We will take a closer look at these two bridges in the next few days.
Portland's Bridges: Burnside, Morrison, and Hawthorne Bridges by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 United States License.