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Multnomah County engineers are still debating the best fix for the deteriorating Morrison Bridge deck as a jury trial continues this week over a botched $4.2 million steel grating replacement project.

The span was closed to traffic Sunday for continued repairs to the fiber-reinforced polymer (FRP) decking panels; they were found defective shortly after installation three years ago because of cracking and failure of the fastening system. The county is suing the contractor that installed the deck that replaced the bridge’s original steel grating as well as the panels’ manufacturer and supplier and the project engineer for the cost of repairs, valued at $2 million, according to court documents. The Multnomah County Circuit Court trial started last week and is scheduled to continue through Friday.

Applying temporary fixes to the Morrison Bridge deck can go on for only so long, especially after a recent discovery of cracks in the structure below the panels, county spokesman Mike Pullen said. County engineers hope to decide by this spring what material should replace the failing FRP panels and start design work on a second deck replacement project, potentially funded by an award from the lawsuit and state and federal sources, he said. Construction could start in 2016 or 2017.

鈥淭here’s an urgency here,鈥� he said. 鈥淚t’s definitely our highest priority bridge project.鈥�

In the meantime, the county will continue to close the bridge periodically to make repairs.

鈥淲hat we’re doing this year is really a Band-Aid to give us more time,鈥� Pullen said.

County engineers need the extra time because determining what type of material should replace the lightweight polymer decking on the drawbridge is a bit of a puzzle, he said. Officials have considered steel grating, aluminum or again using FRP, but each option has drawbacks. Open steel grating, used originally, doesn’t provide good traction when wet and isn’t ideal for cars traveling at high speeds. Aluminum panels are less slippery, but considered more experimental. As for FRP, the county is suing the only company that uses the material for bridge deck panels.

More recently, county officials have investigated whether it would be possible to use a material that is heavier than the bridge’s original open-grating deck, such as steel grating half-filled with concrete to add traction, Pullen said. This would likely require strengthening the bridge and beefing up its 950-ton concrete counterweights to lift the heavier deck, he said.

鈥淭he old assumption was to keep the weight of the material at or close to the steel grating,鈥� he said. 鈥淲e’ve taken a new tack to see if we can use a tried-and-true deck method.鈥�

The challenge is that the steel truss double leaf bascule bridge essentially acts like a giant seesaw and wouldn’t lift if too much weight was added, Pullen said. County engineers, together with consultant David Evans and Associates, are working to determine this max capacity.

鈥淚t’s an interesting engineering challenge,鈥� he said. 鈥淭he bridge is designed for one weight and (we’re) seeing how much can we add.鈥�

The Morrison Bridge’s deteriorating deck was installed between 2011 and 2012 by Ridgefield, Wash.-based Conway Construction Co. Problems surfaced within the first year following project completion, when polymer panels appeared worn and began to loosen, Pullen said.

Conway in 2013 filed suit against the panels’ manufacturer 鈥� Durham, N.C.-based ZellComp Inc. 鈥� and supplier 鈥� Bristol, Va.-based Strongwell Corp., blaming the companies for the failing panels. The county later joined the suit, claiming that the contractor was also responsible for the botched project, and filed another suit against New York-based Hardesty & Hanover, which designed the fiber-reinforced polymer system.

Expert witnesses who testified last week during the ongoing trial included engineers hired by attorneys representing parties involved in the case to investigate what went wrong with the Morrison Bridge deck replacement project.

ZellComp witness Robert Lindyberg, vice president of Raleigh, N.C.-based engineering firm FDH, testified on Friday that his lab research involving a piece of the FRP deck panel taken from the Morrison Bridge showed that the panels the company manufactured were not defective.

鈥淭he only opinion I really reached was that as designed and manufactured the Zellcomp deck is structurally adequate,鈥� he said.