When heading up to Tamarack Ski Resort in Donnelly, there’s a bridge visitors must cross that has a somewhat watery reputation: The S-bridge, on Roseberry Road over Lake Cascade.
The bridge was constructed during the 1960s. At that time, only a handful of residents were crossing the bridge. Jeff McFadden, Valley County’s Road and Bridge Superintendent, said there would have been about 20 cars passing over per day. Several decades later, traffic counts are pushing 20,000 cars a week.
“The design of it just does not handle that kind of traffic,” McFadden said.
McFadden said during the ‘60s, rock was a cheap material used to build bridges. And designing the bridge perpendicular to a body of water with curves, as opposed to straight but at an angle, was less expensive because the bridge could be shorter.
“I think it’s a 103-foot-long (bridge). So, that’s the cheapest way you could build a bridge back then,” he said. “And build anything perpendicular to it instead of trying to span an angle creek or river, making your bridge three times longer. So, that’s why they did it that way because rock was basically free and that was the cheapest way they could build a bridge was perpendicular to the water body.”
While repairs have been made to the bridge over the past 15 years, the structure has largely stayed the same.
“The bridge has not changed,” McFadden said. “We’ve done some repairs on it in the last 15 years. One was pretty major. We had to close the bridge for a day and dig out one of the abutments and fix it. That was the only major thing we’ve done to it. Twelve, 15 years ago, we ground all the asphalt off all of West Roseberry from Donnelly to Norwood and repaved it. We put new guardrail up on that S-bridge.”
Crash data
Looking back over the last decade from 2013 to 2023, there have been 26 total crashes on the S-bridge, according to the Idaho Transportation Department. Of those, there were 0 fatalities, one suspected serious injury, five possible injuries/ complaints, and 20 counts of property damage recorded.
Twelve of the 26 accidents happened during the winter months. ITD crash data shows that people driving too fast for the weather conditions accounted for 15 of the crashes, failing to maintain lane accounted for seven, inattention accounted for three, and overcorrection accounted for the remaining three.
“In the wintertime, bridges are icy, but people come up here and they just forget,” he said. “Their brain just goes out the window because they’re going skiing for the weekend or something. They come off the highway, which is treated with 4,000 tons of salt all winter long, and they hit our roads and most of our roads are ice covered. Except for that when we try to keep it as bare as possible, but it’s a bridge over a water body so there’s a lot of humidity there and it causes ice.”
Will there be a rebuild?
To help address weather-related crashes, McFadden says the county is installing temperature-sensitive signs that will flash when the road is icy to catch drivers’ attention.
Despite its age and the influx of traffic, the bridge is still rated as good. This means it does not qualify for the normal process of federal funding that would be used to rebuild.
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If a new bridge was built, McFadden says it would be built straight without curves because West Roseberry is on a straight section line. However, this would mean the structure would be much longer, about 1,500 feet compared to the current 103 feet.
The extra footage and new material comes with a steep price tag.
McFadden said the “ballpark figure” for a new bridge of that magnitude would cost anywhere from $10 to $30 million.
He said if the rebuild process were to start right now, it would take about five years to complete.
Along with funding, there are a number of other factors that make the bridge rebuild complicated.
“Funding and environmental studies, those are the main ones,” McFadden said. “As it crosses through the Bureau of Reclamation property, there’s gonna have to be environmental studies done on critters, and creatures, and aquatic organisms, and all that other good stuff, wetland studies.”
There are still some funds available that would help get the project started. McFadden says the county is applying for several large grants that would help pay for the engineering side of redoing the S-bridge. But for the foreseeable future, the winding section of path toward Tamarack will remain.
