Innovative Bridge Design Saves Months in Construction Schedule

Topics: Accelerated, Blog, Case Study, Innovation, Prefabricated, Press Brake & Folded Plate

The town of Roseville, Ohio has a new short span steel bridge in place – the first of its kind in the state, with results that are attracting attention nationwide from county engineers; federal, state and local transportation officials; and bridge owners.

These results include:

Saving 3-4 months of construction time by fabricating the structure offsite.
Setting two modules on abutments in just 22 minutes.
Using a local crew for installation.
Completing the project ahead of schedule in just 26 days, which included demolishing the original bridge and abutments and adding new abutments and superstructure.
Expecting a service life of more than 100 years.
Cannelville Road Bridge in Muskingum County, Ohio

A New Way to Design and Install Short Span Bridges
The new Cannelville Road Bridge in Muskingum County, Ohio is a press-brake-formed steel tub girder (PBTG) bridge. Its unique design allows ease of delivery, accelerated bridge construction, and minimal maintenance during its lifetime.

The PBTG design consists of two modular shallow trapezoidal boxes fabricated from cold-bent structural steel plate. After the plate was formed for this project, a thin lightweight Sandwich Plate System (SPS) deck was bolted to the girder in the fabrication shop and guardrails were added, making it a modular unit that could be quickly assembled at the bridge site.

Two trucks delivered the bridge to the project site in prefabricated half-width modules, with each weighing approximately 31 tons. Both modules were erected and positioned on their abutments in just 22 minutes and bolted together in one day.

A waterproof membrane and asphalt wearing course were subsequently applied. The bridge deck was metallized with zinc on all surfaces to provide additional corrosion protection from the low pH levels of the stream. Other superstructure components were hot-dipped galvanized to prevent corrosion from road chemicals.

Press brake tub girder bridge were erected and positioned on their abutments in just 22 minutes and bolted together in one day.

The PBTG system was chosen for this project because it was an ideal structure for the design challenges of this particular area, which has steep ravines and low-lying areas. The stream fills up and drains quickly after stormy weather, transporting large debris such as root balls and tree limbs. Other design options would have allowed the debris to collect underneath the bridge and cause damage. But with the smooth tub girders of the new bridge, debris easily flows under it.

The new bridge was financed in part with research funding from the Federal Highway Administration (FHWA). It was constructed by a local crew in just 26 days, ahead of schedule. The work included removal of the existing bridge and abutments and the construction of new foundations, abutments and superstructure. The new bridge is longer than the previous structure at 52 feet, 6 inches; is 24 feet wide; and is designed to remain elastic under a TL-2 crash event. It was opened to service on May 27, 2017.

Doug Davis, P.E., P.S., Muskingum County Engineer, oversaw all aspects of the construction and installation of the new bridge and is ready to construct more of them.

The Cannelville Road Bridge is the second PBTG structure to be completed in the United States. The first PBTG structure was the Amish Sawmill Bridge in Buchanan County, Iowa, which utilized a cast-in-place deck and was opened to service in January 2016.

What are Press Brake Tub Girders?

Press-brake-formed tub girder (PBTG) is a new technology for short span bridge applications. It consists of modular galvanized shallow trapezoidal boxes fabricated from cold-bent structural steel plate (watch fabrication video). A concrete deck is recommended to be precast on the girder and the modular unit can be shipped by truck to the bridge site.

The system utilizes standard plate widths (based on availability) and is optimized to achieve maximum structural capacity, with most of the steel in the bottom flange and increased torsional stiffness. It is a closed system, since the girder is closed at the bottom. It is versatile for multiple-deck options.

The system utilizes Accelerated Bridge Construction practices, since it:
- Can be installed in one or two days
- Is modular, allowing the use of a precast deck
- Is cost-effective―as much as 1/3 less than a standard concrete girder structure
- Is simple to fabricate, requiring very little welding.
The Short Span Steel Bridge Alliance has developed standardized plans using standard plate sizes (60”, 72” 84”, 96”, 108”, 120”). The designs were developed to achieve maximum structural capacity and are available to use in the free-to-use, web-based design tool eSPAN140.

The press-brake-formed tub girder system is open source.

Learn more about press brake tub girders→