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Bridge construction may take a big seismic step forward if a new span in Seattle performs as expected.

鈥淚 think over time this could become one of the more common methods of resisting earthquakes,鈥� said Tom Baker, an engineer with the Washington State Department of Transportation.

The , which serves as an exit ramp from State Route 99 into downtown Seattle, involves using shape-memory alloy (SMA) bars in the columns and engineered cementitious composite (commonly called bendable concrete) in the road surface. The combination should, in theory, allow the bridge to snap back into shape after a major earthquake.

鈥淚t’s the first of its type in the world,鈥� Baker said of the bridge.

Traditionally, bridges have been built to simply remain standing after an earthquake. Even if a bridge has been damaged beyond repair from a seismic event, the absence of a collapse is considered a success.

Then a professor of civil engineering at the University of Nevada-Reno, M. 鈥淪aiid鈥� Saiidi, came up with an idea that should allow bridges to not just survive a quake but be usable almost immediately afterward.

鈥淚 accidentally heard about this smart memory alloy that can absorb energy,鈥� he said. 鈥淚t was used in the form of small mechanical devices in mechanical engineering. I thought, what if I brought this into bridge material?鈥�

Saiidi said that the materials helped address two major problems with traditional bridge design, which focuses on strength and diverting energy away from the span. First, while the bridge may be left standing after a quake, it is often tilting to one side. The second problem is that columns tend to fall apart. Either issue means the structure has to be shut down for repairs or replacement that can take weeks or months.

After nearly 15 years of design work and testing, the concept was deemed ready for its first use in Seattle. The SMA bars are used in the top five feet of the two middle columns, where most of the stress occurs during a quake. The bottom two-thirds of the columns are built with standard materials. The high-fiber bendable concrete is then poured on top of the SMA bars.

鈥淲hat made us try a field trial was the success of Dr. Saiidi’s laboratory work,鈥� Baker said. 鈥淲e wanted to get a full-size test.鈥�

A lot will be learned by how the structure performs in the real world after surviving simulated quakes of magnitude 8 or more in a laboratory.

鈥淎 couple things we will learn,鈥� Baker said. First, 鈥渉ow it will work without an earthquake. If we do have a quake, how well it will perform compared to its performance in the lab.鈥�

A major issue that could hinder widespread use is cost. A $400,000 grant from the federal government covered most of the added costs of the 400-foot expanse, which has cost the city and the state $4.8 million so far. The project is part of the much larger $3.1 billion Alaskan Way Viaduct program.

Saiidi said that he and researchers in Japan have been working to develop a next generation of materials that could bring the costs down.

鈥淲e have worked on smaller bars, but they are not something you can use in a bridge,鈥� he said. 鈥淭he latest developments in Japan have used bigger-diameter bars that could be used in bridges.鈥�

Outside of Washington, the Japanese have shown the most interest in the new technology. Others in the U.S., including Multnomah County officials, are beginning to show interest.

鈥淚t is so new that it wasn’t considered for the Sellwood Bridge (replacement),鈥� said Mike Pullen, Multnomah County spokesman. 鈥淲e are definitely interested in learning more about what they learn in Seattle.鈥�

The county maintains six area bridges. It is looking into major repairs for at least three of them 鈥� including the Burnside and the Morrison bridges 鈥� in the near future.

鈥淲e will definitely look at it in the future,鈥� Pullen said.

He said that the current standard the county uses when designing bridges to resist earthquakes is to ensure service restoration within 48 hours. Most bridges in the area are designed to drive the force of an earthquake away from the span instead of trying to bend and snap back into shape.

The Seattle bridge’s performance will be observed by many interested parties.

鈥淲e applaud our neighbors in the north for trying something new to withstand earthquakes,鈥� Pullen said.