Long-lasting 'detours'.

Byline: The Register-Guard

The Oregon Department of Transportation has known for a couple of years that the Interstate 5 bridges over the Willamette and McKenzie rivers in the Eugene-Springfield area need to be replaced. Typically, traffic would be routed over temporary bridges while new spans were installed in the old ones' place.

Now, however, ODOT wants to install the temporary bridges as soon as greenway and other environmental permits can be obtained, with construction starting by the end of the year. The temporary bridges - ODOT calls them "detour bridges" - will carry freeway traffic across the rivers until more expensive permanent bridges can be built as part of a statewide bridge repair and replacement plan.

Travelers on I-5 will be living with the temporary bridges for quite a bit longer than expected - probably several years. ODOT's decision underlines the urgency of Oregon's problem with deteriorating bridges, and raises worries about what might happen if funding for the permanent Willamette and McKenzie bridges is delayed or never comes.

The existing bridges are so badly cracked that trucks requiring special weight permits have already been detoured to other routes. ODOT now worries that the I-5 bridges could deteriorate further, leading to tighter weight restrictions. If trucks weighing the legal limit of 80,000 pounds were prohibited from using the I-5 bridges, the volume of heavy truck traffic on other highway bridges would increase, the freeway would carry a larger number of lighter trucks, or both. West Coast commerce would suffer, consumer prices would rise and congestion would increase.

The Willamette and McKenzie bridges aren't the only ones nearing the end of their useful lives. ODOT estimates that in 10 years, 30 percent of the state's bridges will need reconstruction or replacement. The department plans to tackle the massive job in stages, rebuilding bridges on each of the state's major transportation corridors in turn. Bridges on the section of I-5 between Salem and Oregon Highway 58 were to be built in the third phase of a five-phase program taking a decade or more.

That timetable suggests that permanent replacements for the Willamette and McKenzie bridges can be expected in five or six years - presuming the Legislature increases vehicle registration fees and other transportation taxes to finance the bridge program. Partial funding might delay projects in the third phase. It's also possible that legislators representing areas served by bridges in the final phases of the program will succeed in getting their projects moved closer to the head of the list. Lane County generally fares poorly in competition for statewide transportation dollars.

Even if the bridge replacement program is fully funded and moves forward as planned, ODOT's alarming assessment of the existing bridges' condition raises a further troubling possibility. These bridges may not be the only ones that merit immediate replacement, by temporary bridges if necessary. If the temporary bridges do an adequate job of moving freeway traffic across the Willamette and McKenzie rivers, and if ODOT finds itself with a long list of other bridges around the state demanding urgent attention, the Eugene-Springfield area might find itself making do with the temporary bridges for a long time.

The most encouraging note in the revised plans for the Eugene-Springfield area bridges came when Dean Fuller, ODOT's local project manager, mentioned the possibility of a "signature bridge" across the Willamette River. That crossing would be a perfect place to showcase the art of bridge architecture. If local and through traffic is asked to make do with temporary bridges for years, there should at least be the consolation of being able to look forward to the eventual construction of a graceful permanent replacement.