July 10 UPDATE
Massive boulders came down last night at the U.S. Highway 95 slide south of Riggins (milepost 188). The slope above the route remains too unstable to allow for traffic or rock removal crews in the area.
“The highway will remain closed until we are able to evaluate this new development and determine the best option to safely stabilize the slope.” Operations Engineer Jared Hopkins said.
The department had already built a temporary gravel road to detour traffic around the base of the slide, but continued significant movement on the slope closed it on July 8.
“The extensive rock fall that occurred last night confirmed that we had made the right decision to completely close that portion of US-95 to traffic,” Hopkins said.
Early next week, crews will again begin scaling the slope and surveying the area.
“Currently there are a lot of overhanging boulders and ledges,” stated Hopkins. “We don’t yet know how stable these are and until we are able to further evaluate the area, crews will not be able to engage in rock removal operations.”
Old Pollock Road will continue to serve as a detour around the slide during daytime hours – 6 am – 8 pm PDT (7 am – 9 pm MDT). The detour will remain closed at night in order for crews to perform maintenance operations on the roadway, which typically does not see this amount of traffic.
“It’s very important that we maintain the integrity of Old Pollock Road so that it can continue to serve as a viable option for detouring traffic during this time,” Hopkins said.
The slope and area around the slide is considered extremely hazardous. ITD is asking citizens to stay away from the area for their safety. The department is also asking drivers choosing to use the detour, to ensure that they drive attentively in order to keep traffic flowing.
“The proven unpredictability of this slide requires that we remain flexible,” Hopkins said. “While our goal is to safely reopen the highway as soon as possible, we are very thankful that no one has been injured and will focus our efforts to ensure that it remains that way.”
Updates will be provided on the status of the slide as they are made available. At present, there is no estimated time for reopening of the highway.
July 8 evening update
The recently reopened detour around the US-95 closure south of Riggins due to a July 3 rockslide will not open tomorrow following discovery of significant movement on the slope. This closure is anticipated to last at least two days.
“Between Monday and today, one of our survey targets moved nearly two inches,” Operations Engineer Jared Hopkins said. “That kind of activity may not sound like much, but in terms of geological movement it is alarming.”
The continued closure at US-95 will allow geotechnical experts to perform intensive scaling activities to dislodge the rock and reassess site conditions.
During the closure, Old Pollock Road will serve as a detour for both passenger and commercial traffic.
“This is a one-lane gravel road that is nearly four miles long,” Hopkins said. “Even with this open, getting through the area could take up to three hours.”
Repairs to Old Pollock Road were completed earlier tonight. Flaggers will be on scene tomorrow morning at 6 a.m. PDT / 7 a.m. MDT to direct alternating traffic.
“Slides are unpredictable, and this one keeps proving that,” Hopkins said. “For the safety of drivers and our workers, we have to close it. Until this problem is solved, we recommend that drivers check 511 every time they travel on US-95.”
July 8 morning update
U.S. Highway 95 will open to one lane of traffic between Pollock and Riggins this morning by 10 a.m. PDT/ 11 a.m. MDT and stay open until 8 p.m. PDT/ 9 p.m. MDT for the first time since the July 3 rockslide closed it at milepost 188.
Drivers will pass around the slide on a temporary gravel road. They should expect lengthy delays as only a limited number of vehicles will be allowed to pass underneath the slope at one time. Scaling activity above will also require periodic 20-minute closures over the next couple of days.
“We have built a rock berm and placed large container boxes to shield traffic from any unforeseen rockfall,” Operations Engineer Jared Hopkins said. “A spotter and a surveyor will watch the hillside and be ready to have flaggers close the highway in the unlikely event it becomes unstable.”
Starting Thursday, ITD plans to open the highway from 6 a.m. PDT /7 a.m. MDT to 8 p.m. PDT/ 9 p.m. MDT each day. Approximately 30 minutes before the highway is closed each night, staff at barricades in Riggins and New Meadows will turn traffic away.
Crews will continue breaking down rocks and pushing them up against the existing berm to make it taller and provide more room for any further debris.
Improvements to Old Pollock Road will be completed later today, serving as another one-lane gravel option for local commuters only but not commercial traffic.
“For the time being, motorists should plan for congestion and expect the highway to be closed at night when we can’t monitor the slope,” Hopkins said. “We expect to keep flagging and monitoring for several weeks until we identify a long-term solution.”
Another update will be released when the long-term solution is identified next week.
July 7 update
The Idaho Transportation Department plans to open US-95 to traffic between Pollock and Riggins tomorrow, Wednesday (July 8) following the evaluation of geotechnical experts yesterday and positive results from continued monitoring. The highway will only open during the day to allow observation of the slope.
“Yesterday geotechnical professionals measured the slope to identify short-term options to get the highway safely open,” Operations Engineer Jared Hopkins said. “Today rock scalers will keep dislodging any loose material.”
Crews have closed Old Pollock Road to add gravel and install culverts to help the county repair it for local and commuter traffic. Work is expected to take up to two days.
Recent rain could affect the stability of the slope. More details will be released tomorrow morning.
July 6 evening update
July 6 morning update
Results from geotechnical surveys on the slide south of Riggins showed significantly less movement on the slope yesterday (July 5), but the highway will remain closed today (July 6) to allow for more monitoring.
Outside experts are examining the slope today to identify short-term and long-term options to stabilize the area. They are also dislodging any loose material.
“By tomorrow morning, we will have more data to compare to the baseline conditions of the slope,” Operations Engineer Jared Hopkins said.
Crews have finished constructing the temporary road around the slide at milepost 188 and have placed barriers to protect future traffic from rockfall.
“When survey results and on-slope evaluations prove that the slide is stable, we will look to open the highway for short periods of time,” Hopkins said. “In the meantime, we are evaluating the condition of Old Pollock Road to see how we may be able to help the county with a locals-only detour.”
The Idaho Transportation Department has submitted feedback to Google Maps to show that Old Pollock Road is currently not open to traffic. There is no detour around the slide.
July 5 update
U.S. Highway 95 will no longer open to traffic between Pollock and Riggins this afternoon to allow for continued monitoring of the slide at milepost 188.
“We know this is contradictory to what we had hoped to accomplish today and will cause long detours for travelers heading home,” ITD District Engineer Doral Hoff said. “However, without enough data and uncertainty about an apparent gap at the top of the hillside, we are concerned it might be active still.”
Yesterday around 4:30 p.m. crews left the site once a crack in the rock face became visible from below. They had been working on a temporary road around the slide as well as building a rock berm and placing container boxes to shield traffic once allowed to pass through.
“The very nature of slides is unpredictable,” Operations Engineer Jared Hopkins said. “At this time, we’re not sure when we will be able to open the highway, but we are continuing to conduct geotechnical surveys and tomorrow will have experts on the slope to pry off any loose material and further analyze its condition.”
July 4 update
Depending on geotechnical survey results, US-95 between Pollock and Riggins may temporarily open tomorrow afternoon (Sunday, July 5) to allow traffic to drive around the rock slide that has closed the highway since Friday morning.
“We were fortunate that there was no further activity last night, and if repeated surveys show no more movement, we are prepared to open the highway for a short time,” ITD District Engineer Doral Hoff said. “We have surveyors on site right now to periodically gauge the stability of the slope.”
Around 9 a.m. Friday, the slope above milepost 188 crashed onto the highway, leaving a debris field approximately 120 feet long and 40 feet deep at the base. Some rocks measure 25 feet across and just as tall. Continued rockfall throughout the day kept maintenance crews from cleaning up the slide.
Equipment and operators from across the region have been called to the area. Crews are actively working to build a temporary road around the slide with a tall berm and container boxes to protect drivers in the event of more rockfall.
“Even with those protective measures in place, the biggest threat to drivers’ safety will be the stability of the slope above them,” Hoff said. “We cannot open the highway until we know it’s safe, and we won’t know without more surveys taken over time.”
Another release will be sent Sunday morning to confirm any opening of the highway.