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Local officials wonder if I-5 overpass work could cause Medford to exceed carbon monoxide limits, but a DEQ air-quality planner doesn't think so

Traffic delays, yes, but air should be OK

Medford's battle against carbon monoxide emissions has been so successful that the city is likely to stay in compliance with pollution limits even as lines of traffic form during the Interstate 5 viaduct overhaul next year, state officials say.

However, the federal Environmental Protection Agency has warned that if CO exceeds legal levels twice during the six-month project, Medford will face penalties.

Violating CO limits in two eight-hour periods would take Medford into noncompliance, forcing it to formulate a new maintenance plan for submission to the EPA. The city has just completed such a plan following a period of noncompliance, and it is to be approved by Nov. 1, said Monte Grove, Oregon Department of Transportation.

I've looked at the data, and the decline (of CO) is so far below what you've seen there that I don't anticipate they would exceed limits, said Annette Liebe, air quality planner for the state Department of Environmental Quality in Portland. They've made tremendous improvements, and the new car technologies have helped a lot. It would take something dramatic (to exceed limits).

Overhaul of the half-mile-plus viaduct will cut traffic to one lane each way from January to June next year, diverting 40 percent of I-5 traffic to Riverside, Central and Court, with some using roads east of the freeway, said Grove.

Traffic officials expect viaduct traffic will be backed up one to two miles in peak times, with many additional vehicles idling at lights on city streets, he said. Trips on the freeway will be cut from 45,000 to about 27,000 a day.

Mike Montero, chairman of the Medford-Ashland Air Quality Advisory Committee, wrote the EPA in Seattle early this month asking if Medford, because of the one-time, temporary bottlenecking of 15,000 daily local trips between the two interchanges, might be excused from potential penalties for CO emissions.

The letter expressed grave concern that the project-specific anomaly would jeopardize the maintenance plan created through advances of recent years.

The EPA told the DEQ that it does not grant exceptions to its rules on emissions levels, Liebe said.

The reductions have been achieved, said Grove, by planning the transportation system so people keep moving and drive less, by new vehicle emissions technology and by use of oxygenated fuels in winter. If the area's maintenance plan is approved as expected, it would no longer be required to use oxygenated gas, he said.

Both the freeway and other routes will be stressed during the &

36;15 million project, said Grove. However, the length of the work, originally estimated to be 18 months, was cut to six months by paying incentives and keeping crews on the job 24 hours every day.

The project was scheduled for the winter to avoid high-traffic season and the complication of increased ozone emissions, which come only in the summer. After improvements, he added, the viaduct should last another 20 years.

John Darling is a free-lance writer living in Ashland. E-mail him at jdarling@jeffnet.org.

Interstate 5 traffic will face tough going at the viaduct in Medford next year while crews repave and strengthen the structure. Mail Tribune / Bob Pennell - Mail Tribune Bob Pennell