Time Zone Bridge Over Salmon River Heading West Move Will Close Highway 95 For 72 Hours

In an unusual engineering feat, the Idaho Transportation Department plans to move the 61-year-old Goff Bridge over the Salmon River 65 feet to the west.

Once set in a new location, the old bridge will be used as a detour while a new, $12.4 million bridge is constructed.

Engineers plan to use giant casters and rails to slide the old bridge, two miles north of Riggins, to its new location. U.S. Highway 95 will be closed to traffic at the crossing for three days, June 20-23.

“This is the most important bridge in the state,” said Thomas Pfister, the department’s lead designer for the new bridge. “There is no way to go from north to south Idaho without it.”

Officials plan to alert commercial travelers and emergency services. Once U.S. 95 is shut down, a trip between Lewiston and Boise means a 550-mile detour through Oregon and Washington. Road closure signs will be posted between the two Idaho cities and also across the Montana border at Lolo.

To reach Lewiston from Boise during the closure travelers will have to take Interstate 84 west to Pendleton, Ore., turn north on Oregon State Highway 11 to Walla Walla and take U.S. 12 east to Lewiston.

To encourage the contractor to make the move in 72 hours, the Transportation Department has come up with unusually strict penalties for delays.

If the contractor, Harcon Inc., Spokane, can’t complete the bridge move in 72 hours, the penalty will be $625 for every 15 minutes it is late, $2,500 per hour.

Closing the road on a weekend is designed to pose as little inconvenience to the public as possible. Nearly 2,000 vehicles per day use the bridge, 330 of them commercial.

The bridge, named after early local pioneer John Goff, also is known as the Time Zone Bridge because it marks the boundary between the Mountain and Pacific time zones in Idaho.

The current bridge was built in 1935-36. It replaced a smaller steel and timber truss bridge built in 1911. The first bridge also was moved. It went about 50 miles north to Stites, where it spanned the South Fork of the Clearwater River.

Winds must be under 20 mph when the move is made, and it will be called off if the Salmon River is running too high. The high-water period for the Salmon usually starts in mid-May and runs through June.

The river has been known to come within a few feet of the bridge’s roadway. The new bridge will be five feet higher, longer and wider.

Current speed is 45 mph and the 24-foot bridge is so narrow that two large trucks can’t pass on it. The new design will allow 65 mph travel and be 47 feet wide.

Construction is expected to be finished by the winter of 1998.