Evaluation of Timber Bridge Wear Surfaces

Project summary:

The purpose of this research is to respond to a rural infrastructure request for an evaluation of timber bridge wear surface performance. The initial phase of this research will examine and define the problem with wear surfaces and then an extensive search will be made to gather information on these problems and their possible solutions. Preliminary information indicates that the inadequate performance of bituminous wear surfaces result from cold weather transverse cracking, extension of microcracks due to steep thermal gradients, timber bridge deflections exceeding bending capabilities of bituminous materials in cold weather and presence of free creosote which interferes with the wear surface - timber deck bond. This research will help identify which problems predominate in wear surface deterioration and also identify the deterioration with a particular type of bridge. The investigation for solutions to these wear surface problems will look into alternative wear surface materials, changes in bituminous mix, control joints, stiffening the bridge and/or controlling free creosote. Solutions to wear surface problems will help MnDOT and local county engineers reduce bridge maintenance costs and improve safety.