Short Span Steel Bridge Alliance

The start of a new year — and a new decade — is a good time to take inventory of the way you currently do things and reassess past priorities and practices.

If you’re a highway bridge owner, engineer, or designer and cost efficiency is what drives your materials decisions, it’s time to take a new look at using steel for bridge structures with lengths of up to 140 feet. A common misconception is that steel is more costly than other materials for short span bridges—but that’s typically not true.

A case in point is the Scott County Bridge in southeast Missouri. The bridge, MoDOT Bridge No. A8682, is located on Route W over Drainage Ditch #289 between the towns of Sikeston and Cape Girardeau. The replacement bridge was designed as a single 45’-0” span x 26’-8” width structure; wider than the original structure to accommodate two 12-foot lanes; and longer for improved hydraulics.

Bids were accepted for both a prestressed concrete I-beam and rolled steel beam alternate, both four-beam lines. The concrete I-girders were 2’-8” deep, while the galvanized steel rolled beams were 2’-6″, saving 2 inches in bridge depth.

The project was bid by eight general contractors. Half of them bid steel, and the other half bid concrete. For both the bridge and the overall project, which included all of the roadway items, steel came in low. For bridge items only, the galvanized rolled steel beam was still the lower-cost option, beating out concrete by 2.5 percent.*

Bids for the Scott County Bridge were accepted for both a prestressed concrete I-beam and rolled steel beam alternate, both four-beam lines. For both the bridge and the overall project, which included all of the roadway items, steel came in low. Photo by Gary Wisch.

The contract was let on December 14, 2018 and awarded in early January 2019 to Delong’s, Inc. Steel was delivered during the week of April 1, 2019. The structure was completed and opened to traffic during the week of May 19, 2019.

Short span steel bridges deliver significant cost savings because of steel’s light weight, the allowance of smaller abutments, rapid installation, and the use of lighter equipment and local crews. Steel also delivers durability with an expected service life of more than 100 years for many bridges, considerable life cycle advantages, and minimal maintenance requirements over the service life of the structure.

You can design a structure like the Scott County Bridge for free using web-based design tool eSPAN140. The tool offers customized steel solutions for bridges up to 140 feet in length, with results delivered in less than five minutes. eSPAN140 can be accessed at https://www.espan140.com/.

If you have never installed a short span steel bridge or have minimal experience, challenge yourself this year to learn more by visiting www.shortspansteelbridges.org or contacting Dan Snyder at dsnyder@steel.org.

*Bid Tab Results: Missouri Department of Transportation Bid Tabulations.

For more information:

1. Case Study: “Short Span Shake-Up: Missouri Short Span Bridge Study Finds Steel Saved 25 Percent Over Concrete” — In a side-by-side comparison of construction square footage costs for nearly identical steel and concrete bridges in Audrain County, Missouri, the steel short span superstructure provided a 25.8 percent cost savings with an overall 19.3 percent savings in the total cost of the structure.
2. Fact Sheet: “Steel Offers High Value for Bridge Life Service and Life Cycle Costs” —This fact sheet presents the results of research conducted to explore the initial costs, life cycle costs, future costs and bridge life of 1,186 typical steel and concrete state bridges in Pennsylvania built between 1960 and 2010.
   

   For bridge items only, the galvanized rolled steel beam for the Scott County Bridge project was still the lower-cost option, beating out concrete by 2.5 percent. Photo by Gary Wisch.

Sometimes, the best solutions to challenges we face can be hidden in plain sight. A new video released by the Short Span Steel Bridge Alliance (SSSBA), National Corrugated Steel Pipe Association (NCSPA) and Big R Bridge invites cash-strapped, time-challenged bridge designers and owners to look beyond traditional above-ground bridge design solutions and consider a proven durable, cost-effective alternative.

The five-minute video covers the construction of the 200th Street Bridge in Buchanan County, Iowa, where a steel buried bridge was chosen to replace a 40-foot-long, two-span timber stringer bridge built in 1956 that had rotting timbers. Interviews with Buchanan County Engineer Brian Keierleber, P.E.; Joel Hahm, P.E., Senior Engineer from Big R Bridge; and contractor Eric Zieser from Zieser Construction provide an interesting case study on the overall benefits of steel buried bridge systems and technical details on why this type of design was selected for this particular project. View it here.

Structural steel plate used as buried bridges is a viable design option in almost all cases where a traditional bridge is used due to industry advancements in design and analysis tools, as well as deeper corrugation profiles that allow for longer spans, heavier loads, and higher cover. This design is particularly useful in the 25-foot to 80-foot span range.

Design Advantages
Steel buried bridges are durable and resilient, with the ability to support very heavy loads. Cars, trucks and highway loads pose no problem, as these bridges can be designed to carry mining shovels and other equipment weighing over four million pounds, large off-road trucks weighing over one million pounds, and freight train loads. The secret to their success lies in taking advantage of the proven benefits of soil-structure interaction, where the backfill and structure work together to support the load.

Lead times on the design and material acquisition for a buried bridge are usually much faster than a traditional bridge, as the structure is pretty much designed by the time the project is awarded. Approval drawings can be prepared very quickly, and in many cases it can take just weeks to go from a signed contract to having a product on site.

Even better, potential buried bridge design solutions can be viewed free of charge with the website tool eSPAN140 developed by the SSSBA and several partners. The tool requires only three project inputs, and provides the user with contact information for SSSBA member companies that can quickly provide a customized design solution. Try it here.

Cost Advantages
Buried bridges take advantage of Accelerated Bridge Construction (ABC) techniques and can be built with local crews using their own equipment. The four-man crew that worked on the 200th Street Bridge had no prior experience on this type of bridge, yet found it easy and manageable to construct using basic equipment. Many buried bridges can be built in two days or less, excluding foundation work.

Since the steel plates stack easily, in most cases they can be shipped to the project site on a single truck, saving shipping costs and reducing environmental impacts. At the site, individual plates can be handled with skid steer loaders, forklift trucks, backhoes, and other light equipment.

Because they are compact, structures can be shipped when ready and easily stored in the yard or at the site and built when the schedule permits.

Maintenance Advantages
There is no bridge deck to maintain on a buried bridge, and there are no joints or bearings to repair and replace, resulting in low maintenance and inspection costs.

Additionally, since there is little differential movement or settlement between the buried bridge and adjacent embankments, the “bump at the end of the bridge” that occurs with traditional bridges is effectively eliminated. As a result, maintenance at the surface is essentially the same as it would be for any other section of the road.

Additional Information
There are many more benefits to steel buried bridges. In addition to the video, the Short Span Steel Bridge Alliance includes a technical Q&A with Joel Hahm on its website. Click here to view the Q&A.

The National Corrugated Steel Pipe Association and Big R Bridge offer additional information on these bridge systems.

In Buchanan County, Iowa, the drivers and passengers of cars, trucks and heavy equipment who cross over the 200th Street Bridge may not even realize they’re on a bridge―but those who designed and built it can be confident that it will provide safe crossings for many years to come.

As a bridge engineer, professor in the College of Engineering and Applied Science at the University of Wyoming, and a member of the Short Span Steel Bridge Alliance’s Bridge Technology Center, Michael Barker, Ph.D., P.E., makes frequent presentations on the economics of short span bridge design to county engineers, state Department of Transportation (DOT) engineers and bridge owners. Over the years, he has received numerous questions about Life Service and Life Cycle Costs, especially concerning steel and concrete girder bridges. His answers were always anecdotal, as research didn’t exist―until now.With a keen interest in finding answers to these persistent questions, Dr. Barker took a sabbatical from the university to conduct his own research. He started with a comprehensive inventory of bridges and consideration of initial costs and installation dates, maintenance costs and timing, and end-of-service dates. After considering the availability of historical data, he narrowed the scope of research to include initial costs, future costs, and service lives of 1,186 typical steel and concrete state bridges in Pennsylvania built between 1960 and 2010.

A portion of Dr. Barker’s research focused on short-length bridges of 140 feet or less, which make up approximately half of the U.S. inventory that needs to be repaired or replaced. The research examined costs with respect to variability in bridge type, span length, number of spans, and bridge life. Typical bridges are defined in the study as those with concrete decks supported by steel rolled beams, steel plate girders, precast concrete boxes, or precast concrete beams. Working from Pennsylvania Department of Transportation (PennDOT) historical records, he developed a database to determine and compare the life cycle costs of steel and concrete girder bridges. More detailed information on the parameters of the research and determination of values for life cycle costs are included in the presentation located here.

For the short-length bridges included in the PennDOT database, the research demonstrated:

• The steel I-beam had the longest life.
• The steel I-beam had the lowest cost.
• Steel bridges have lower future costs compared to initial costs.
• None of the bridges clearly beat out the others, meaning any one type of bridge may be the most economical for a given bridge project.

Overall Results
After analyzing the extensive data collected, Dr. Barker concludes:

• Typical steel and concrete bridges are competitive on initial costs, future costs, life cycle costs and bridge life.
• For any given bridge project, steel or concrete bridge types may be the most economical. Therefore,
• Owners should consider both steel and concrete alternatives for individual bridge projects.

The research results do not provide a clear preference for either material. However, the results clearly disprove generally accepted assumptions by bridge engineers that concrete girder bridges are the least-cost solution for every short span project.

It is clear from the research that bridge owners and design professionals who want to find the most economical and long-lasting solutions for repairing and replacing their bridge inventories should conduct a thorough cost analysis that considers the potential benefits of steel and concrete options. Conducting the analysis upfront could save thousands of dollars down the road in maintenance and repair costs.

To download the complete report, “Historical Life Cycle Costs of Steel and Concrete Girder Bridges,” click here.

To download the Fact Sheet, click here.

For more information, contact Dr. Barker at Barker@uwyo.edu.

It’s no secret that the U.S. infrastructure needs an overhaul, especially for many of its structurally deficient and functionally obsolete bridges – nearly half of which fall in the short span category.

To address this national crisis, the Federal Highway Association (FHWA) introduced the Highways for LIFE initiative to promote the development of bridge design and construction that leads to Long-lasting bridges that are Innovative, have Fast construction times, and are economically Efficient.

The Short Span Steel Bridge Alliance (SSSBA) took on the Highways for LIFE challenge. Working with several partners, the group explored new methods for increasing the efficiency of steel girder bridge design. They developed a set of standardized designs that are now included in an easy-to-use online tool called eSPAN140. Available to use free of charge at http://www.espan140.com/, the tool offers four major sets of bridge designs for spans between 40 feet and 140 feet ― “limited depth” rolled beam sections, “lightest weight” rolled beam sections, homogeneous plate girder sections, and hybrid plate girder sections. The girders are designed in five-foot increments. eSPAN140 provides users with customized steel design solutions for their bridge projects.

Taking the next step, the eSPAN140 developers worked with Buchanan County (Iowa) Engineer Brian Keierleber, P.E. and others to construct the first bridge designed with eSPAN140. Opened to service in 2013, the Jesup South Bridge serves local residents as well as researchers by providing data from live load testing that will serve as a benchmark for future analytical studies on short span steel bridge behavior.

A just-released technical report details the development of eSPAN140 and its associated design standards, provides an overview of the design of the Jesup South Bridge project, and describes the research methods and field tests conducted on that bridge. Using data from both the physical field tests of the Jesup South Bridge as well as the analysis of finite element models simulating the experiments, a series of standardized bridge responses were assessed. The report provides experimental and analytical testing data which proves that eSPAN140 is quite capable of producing efficient and economical solutions in the short span range ― concluding that eSPAN140 provides all the necessary parameters for county engineers to refine and synthesize an effective short span steel bridge design.

Titled “eSPAN140 Performance Assessment: V-65 Jesup South Bridge (Buchanan County, Iowa),” the report is available to download free of charge. Download the report.

Why should county engineers; bridge designers at local, state and federal Departments of Transportation; bridge owners; professors; students and others read the report? Because it provides a detailed look at the future of short span steel bridge design with solutions that can be implemented today:

• eSPAN140 produces customized, efficient and economical solutions for bridges with spans of 140 feet or less.
• eSPAN140 provides the necessary parameters to refine and synthesize an effective short span steel bridge design.
• eSPAN140 expedites the design process and provides a more streamlined process for shop drawing review, eliminating many weeks in the timeline of a project.

While the infrastructure challenges facing the U.S. are daunting, they are not insurmountable. A proven, cost-effective engineering solution is available to those charged with meeting the challenge. It starts with http://www.espan140.com.