- CASE STUDIES
- TECHNICAL INFORMATION
Movable Bridge Design by Terry L. Koglin examines the use of aluminum tread plate on the Scherzer rolling lift bascule bridge. The Scherzer is one of multiple types of bascule bridges (a moveable bridge with counterweights that continuously balance the span). They are the most commonly used movable bridge because they open quickly and require little energy to operate. According to the book, aluminum tread plate was used for most, if not all, early bascule bridges and failed a finite number of times.
During early construction the thinnest tread plates were used, usually one to two inches thick due to expensive material costs. However, the aluminum tread plate would crack and deteriorate, even with the absence of heavy traffic. It was decided that a thicker plate should be used and made of steel with a wider span. Even after this change, the aluminum tread plate continued to fail. It was then understood the replacement of the tread plate would have to be factored into the life cycle cost of the bridges.
An example is the Intracoastal Waterway at Galveston, TX, the tread plates were replaced several times. To avoid the cost of replacing aluminum tread plate on bridges an alternative product can be used. SlipNOT® offers aluminum floor plate that consists of a smooth plate with an all metal slip resistant surface applied with a plasma spray. The SlipNOT® process results in a file hard surface that will not crack or deteriorate and provides a coefficient of friction that is greater than or equal to 0.85.