Large trucks and buses are required to reduce their speed from the posted 55 mph to 30 mph along this 35-mile stretch of highway to minimize the breakup of the roadway surface. Speed and load limits are in effect until the end of the freeze-thaw period. Truck speed and load limits are enforced on Idaho's highways to minimize further damage by extensive breakup and extend the life of the road. This year, with above-normal amounts of rainfall and melting snow, Idaho 55's surface is severely broken up with potholes and rutting.
Cold weather combined with moisture and warm temperatures make the roads susceptible to breakup.
When the ground thaws and refreezes, it creates unstable soil conditions under the road surface. Fast-moving and heavily loaded vehicles can force shifting of the soil and cause the road surface to shift or break down. Other state highways will be receiving these breakup speed restrictions as spring weather dictates. Without these limits, hundreds of thousands of dollars of damage would be done yearly to the roads. When the weather becomes warmer and less damp, the transportation department will be able to patch and pave the breakups on the highway.