October 24, 2001 11:00 pm
The Oregon Department of Transportation installed external stirrups last year to strengthen the I-84 bridge over the Grande Ronde River. (ODOT photo).
The Oregon Department of Transportation installed external stirrups last year to strengthen the I-84 bridge over the Grande Ronde River. (ODOT photo).

By Ray Linker

Observer Staff Writer

ODOT officials have known for some time that the bridges of the state were deteriorating.

Now, when they post load limit restrictions on some bridges, notably the interstate structures, that just directs traffic onto secondary roads. Then, at least in a few years, those roads and bridges will need repairs.

The first day Bruce Warner was on the job, about eight months ago, as the director of ODOT, he had to post an interstate bridge near the small southern Oregon town of Riddle. That bridge restriction redirected heavy trucks away from the interstate and through the town, putting 1,500 trucks a day instead of three on the county roads and city streets.

The Interstate 84 bridge over the Grande Ronde River had to have emergency repairs last year, and that rerouted traffic through Elgin and over Tollgate. Now, two bridges on Highway 82 near Elgin are being monitored for shear cracking.

Of course, it wasnt all the heavy trucks doings. Like the other bridges, they are just showing the wear of time.

The younger, concrete bridges built between 1947 and 1961 using a T-beam construction are beginning to crack, Warner said Tuesday during a visit to La Grande and other Eastern Oregon Cities to meet with local government officials.

While those early bridges met the design specification of the times, the design code was changed in the late 1950s to strengthen bridges as greater load limits became permissible. Later prestress concrete girders have proven to be longer-lived.

With 550 bridges in the state, Warner said, Its a challenge to our department to come up with a strategy to hold the bridges together a little longer, to extend their lives as much as possible, he said.

One thing that is being tried but is still in the experimental state is a system of using a type of epoxy and carbon fibre material placed over the cracks in the concrete structure, explained ODOT Region 5 manager Tom Schuft. This system is being used on the Coles Bridge near John Day, Schuft said. That bridge was repaired Aug. 21-Sept. 17.

Its like fiberglass, he said.

Schuft said there appears to be no further deterioration to the interstate bridge near La Grande, but that some small bridges in Union County may need attention soon.

ODOT plans to spend $100 million to $150 million just for bridge repair, the funds to come from the sale of bonds over the next six or eight years. The bonds will be paid off by an increase in fees charged for new car titling and similar fees, not from an increase in the gasoline taxes, which voters have rejected.

But that is not enough money to deal with the failing bridges all at once, he said.

If a bridge fails, well have to delay another project. Now almost all our dollars are going into emergency repairs, Warner said.

If one interstate bridge fails to the extent it had to be replaced, it likely would cost in the neighborhood of $10 million.

There are some federal dollars for highway bridge replacement, Warner said.

After the last Legislature earmarked $400 million for ODOT work, the Transportation Commission decided to spend $200 million on new construction, $100 million on bridges, $50 million on highway repaving and other preservation projects and $50 million that could go to either bridges or repaving. The money will be spent over the next six to eight years.

The commission has until Feb. 1 to decide on which projects to work on. ODOT is now deciding which bridge projects get funded first.

A lot of that decision will be based on the impact of particular bridges on the states economy, Warner said.

We can only replace eight to 10 bridges a year. I think you will see more postings (of load limits for heavy trucks). We want to keep the interstates open. They are the lifeblood of our economy, Warner said.