Repairs are designed to stabilize the slope and prevent the hill from sliding onto the highway again.
Work will likely begin midsummer and last for two months. The highway will be reduced to one lane with signal-controlled access.
The hill slid onto the road in late March of 2017, moving concrete barrier and depositing debris.
Since then, ITD has reshaped the slope above the road to get the load off, installed barrier to prevent any further debris from falling onto the road and hired a geotechnical firm to drill down for subsurface investigation. Study results helped develop the long-term fix, which will add a rock buttress to hold the hill back where it’s sliding and to improve drainage. Nearly 23,000 cubic yards will be excavated to make room for the buttress.
Starlight Road will also be temporarily paved to allow crews and equipment access during construction.Watch a video of the slide
Although the department typically sets design and construction schedules for projects, emergency repairs set their own.
After a slide, state forces are immediately activated to open as many lanes as safely possible. The initial response is the quickest part of the process, as extra steps must be taken in order to successfully obtain federal aid for permanent repairs. They include installing devices to monitor conditions, securing design approval, acquiring any land needed, etc.
In general, repairs to slides that are still slowly moving, to areas still expected to receive significant moisture or to sites with a high water table are not likely to last.
These factors can significantly affect drivers and the schedule of repairs, whether they are big or small. In order to maximize external and internal resources, ITD must wait until conditions are right.