If you’re a county/state engineer or a bridge owner, cost is always a deciding factor in which material to choose for your next project. A new design using press-brake-formed steel tub girders (PBTG) is providing a durable, cost-saving solution for short span bridge projects.
A PBTG bridge consists of modular galvanized shallow trapezoidal boxes fabricated from cold-bent structural steel plate. A concrete or Sandwich Plate System (SPS) deck is precast on the girder, making it a single unit. Guardrails can be added, and the structure can be transported by truck to the project site. The unit can usually be installed in one or two days by local crews using their own equipment.
Recently, Buchanan County (Iowa) Engineer Brian Keierleber was faced with a decision on how to replace the Daniel Avenue Bridge. Built in 1956, the span is 63 feet long, 21 feet wide and is posted at 17 tons, but still has a sufficiency rating of 57. It is situated on a Class A Road with two houses directly behind it, making the project site a bit challenging to navigate.
Initially, Brian considered steel, concrete T-beams and even railroad flatcars as bridge replacement options because of cost efficiencies and project site challenges. But when the project was let out for bids, he found out he could save nearly $100,000 with a PBTG bridge, even when specifying high chromate steel. This PBTG bridge bid utilizes the Con-Struct™ prefabricated bridge system. Due to the light weight of steel, Brian can save additional costs by reusing the concrete abutments on the current bridge.
A PBTG bridge is a viable option for projects like this because it’s durable, has a modular design so it is easy to transport, and can be installed by a local crew in one or two days, minimizing traffic delays and saving time and money.
PBTG bridges are currently being installed or in service in five states, including Iowa, Ohio, Michigan, Texas and West Virginia. Is this a good solution for your state? Find out more at www.shortspansteelbridges.org or contact Dan Snyder, director of the Short Span Steel Bridge Alliance, at email@example.com.
The spans for the Fourteen Mile bridge near East Lynn, West Virginia were installed on August 20, 2019. This is the first PBTG bridge for WV.