'If certain elements of that bridge are cut, the entire structure collapses'

HARRISBURG, Ore. -- The heavily-used Harrisburg bridge that crosses the Willamette River is built the same way as the bridge that collapsed Thursday in Washington state.

Both are through-truss bridges, meaning drivers travel from bank to bank between two large trusses.

Myra Musial lives right beside the Harrisburg Bridge and said she hears the large amount of traffic that crosses each day, primarily commercial trucks.

"I think that one of these days it's gonna be too much and it's gonna *pshhh* fall in the river," Musial said.

Patrick Cooney with the Oregon Department of Transportation said that a collapse like the one that in Washington Thursday is a possibility, as Harrisburg bridge is one of more than 300 bridges in Oregon that are "fracture critical."

"If certain elements of that bridge are cut, severed broken or collapse or what have you, the entire structure collapses," explained Cooney.

A crash damaged the Harrisburg bridge back in 2010, but the structure didn't collapse. That same year a semi truck clipped Eugene's Ferry Street bridge, which put new height and weight restrictions in place for traffic.

With some of the bridges around Oregon dating back 75 to 100 years old, Cooney said that ODOT keeps an even closer eye on fracture critical bridges.

Folks are going to worry no matter what, but I want to reassure Oregonians that we watch our bridges very closely," said Cooney.

They also carefully monitor the structures for evidence of wear and tear.

In 2002, ODOT found cracks in the concrete of the Interstate 5 bridge crossing the Willamette. ODOT officials said the cracks were caused by nearly 40 years of increased traffic and heavily loaded trailers traveling at high speeds.

While the I-5 bridge isn't fracture critical, officials decided it was time to make some renovations.

"At that time it was designed for a significant smaller load than what it was taken now at a lower speed," construction manager Con O'Connor said. "So here it is 50, 60 years later and they're handling loads going faster that are heavier, but by and large the structure that was here did its job."

According to O'Connor, the new bridge is built to last for the next 100 years.

The Willamette River bridge is expected to reopen to traffic in late summer, which is nearly a year ahead of schedule.