Digging into what went wrong with the Morrison Bridge is proving more complex than the county had planned.

Multnomah County staff, along with a specially contracted forensic engineering consultant, have been working for weeks to determine why exactly a the bridge's new deck is coming loose, shifting around loudly beneath vehicles, and cracking.

The county announced late last month it would close and the bridge's outer eastbound lane for roughly three weeks, then move on to the outer westbound lane. Workers planned to inspect the fiber-reinforced polymer panels attached to to the Morrison in late 2011 and early 2012, to get a better sense of why the deck has failed. But those timelines proved optimistic.

He wouldn't go into detail about what crews are finding on the bridge, but county spokesman Mike Pullen on Friday said inspection of the bridge's eastbound lane was only halfway complete nearly three weeks in.

"Partly due to weather, but party due to the complexity of the investigation," Pullen said. "It's expected it will be several more weeks with the current lane closed."

There's been no shortage of accusations about just what went wrong with the $4.2 million deck replacement, but formal liability likely won't be settled until a court case filed over the botched project is complete.

The county has spent much of its energy assigning blame to the contractor who installed the deck—Washington-based Conway Construction—recently claiming the company did a shoddy job screwing the deck into place. Conway, meanwhile, says the deck wasn't appropriate for a bridge like the Morrison in the first place, and blames the county for approving it. And internal documents show county bridge engineers had serious misgivings about the condition of the polymer decking when it arrived, but elected to use it anyway.

A hearing is scheduled in the case next week.