The Washington Transportation Department says the one-lane, partly paved access road that bypasses the Oso mudslide debris field has been opened to more vehicles.
Transportation officials said Thursday that people traveling to community events in Darrington can use it. Those events include Darrington Day on May 31 and the Darrington Bluegrass Festival on July 18-20.
The road provides the most direct access to Darrington.
Transportation spokesman Travis Phelps says the agency still regards the route as open only to people who live in -- or have a business connection to -- communities along the Highway 530 corridor.
The bypass can now be used by vehicles pulling trailers up to 24 feet long. Also allowed are commercial trucks with trailers up to 33 feet long. And logging trucks can use the bypass at any hour.
With the bypass, the 28-mile drive between Arlington and Darrington can take about 45 minutes. A detour on Highway 20 takes more than an hour and a half.
The speed limit remains 10 mph and drivers follow a pilot car.