Design and construction balances for bascule bridges

The design and construction balances for all movable bridges are critical for their initial erection, continuing operation, and eventual rehabilitation. Several factors must be considered to balance bascule spans. This paper will first cover the sizing and location of new bridge components in the three dimensions (x, y, and z planes) required to properly balance the bridge about the center of rotation and/or trunnion. Rehabilitation balancing will then be addressed with examples given to show potential problems during dismantling, reconstruction, and addition of components.