Heavy timber decks on steel beam bridges.

Delaware County, NY owns approximately 270 bridges and 130 major culverts (greater than 1.5 m (5 ft) long) and performs bridge design, maintenance and replacement with an experienced Department of Public Works’ staff. The County is located in rural upstate New York and is larger in area than Rhode Island. Many of its bridges have relatively low traffic counts, yet are subject to heavy truck loading due to its agricultural, logging, and mining industries. The most common type of superstructure in the County is comprised of longitudinal steel beams (nearly 50% of the total). Deck types include traditional reinforced concrete, transverse corrugated steel pans with asphalt fill, open metal grid decks, and timber (about 15% of the total). Over the past 25 years, the use of timber at DCDPW as a deck material has evolved from nail laminated 50 mm (2 in) nominal thick boards on edge to transverse glu-laminated deck panels to heavy timbers (150 mm x 200 mm (6 in x 8 in) ). Many variations have been tried and details have evolved for construction, connections, and protection. This presentation will include highlights of the evolution of preferences based on engineering, availability, constructability, construction duration, durability, maintenance experience and costs.