New bridge planned near Johnson Creek Airstrip

The narrow, wooden-plank bridge built on a railroad car decades ago at Johnson Creek Airstrip in Valley County just south of Yellow Pine will be replaced this fall. The bridge is important for community, recreational and emergency services.
Yellow Pine is a few hours northeast of Cascade.

“The bridge provides the only access to the Johnson Creek Airstrip, handling both recreational and commercial traffic year-round,” said Dan Gorley of the ITD Bridge section. “The airstrip is an important community asset, providing air access during fire-fighting season, and is designated as a safe zone for Yellow Pine for evacuation purposes.”

The new bridge will be one lane, like the existing one, but wider. The new concrete bridge will be located next to and immediately downstream of the current one. It will be 72 feet and long and 18 feet wide at the bridge deck.

“The bridge will also sit several feet higher in elevation than the old bridge to safely accommodate high water or flood conditions,” said Kyle Arnzen of the ITD Design section for the region.

“The new bridge has been designed to exceed the 50-year-flood water level. The water elevation can change by six or seven feet over the course of the year depending on spring run-off, and often runs over the top or reaches the deck of the old bridge.”

Built in 1959, the bridge is restricted to small vehicles because of weight limits.

Its replacement will benefit the U.S. Forest Service, backcountry aviators and private property owners in the area. It provides access to the Johnson Creek Airstrip (4.5 miles south of Yellow Pine) and to private land.

The project is expected start by late August and be completed in October. Traffic will continue to use the old bridge while the new one is constructed. It will be removed after the new structure and approaches are done.

Work is scheduled to take place on weekdays but could expand to nights and weekends if necessary. No local roads will be closed, but drivers may experience delays during construction.

“Some girders and abutments will be pre-cast to take advantage of accelerated bridge construction (ABC) techniques and reduce environmental impacts while quickening construction time,” Gorley said.

Published 3-23-2012