1. Phenomenon: The rolling width of the road bed is generally or partially smaller than the width of the pavement structure.

2. Cause analysis: The sideline control is inaccurate, or the sideline piles are lost, displaced, trimmed and rolled without basis.

3. Hazard: The rolling width of the dirt road bed is narrower than the width of the pavement structure, and the edge of the pavement structure rests on a soft foundation. When the soft foundation is relatively dry, it has a certain supporting force and the structural layer can survive. When the soft foundation is soaked by rain or moisture accumulates in winter and spring, the soil foundation loses stability. The curb will sink causing it to break.

4． Treatment methods:

(1) Whether it is filling the roadbed with earth or digging the road. When excavating road trenches, surveyors should measure and set edge piles accurately and check whether the pile positions have changed at any time. If any are lost or displaced, piles should be replenished or pile positions corrected in a timely manner.

(2) The rolling edge of the road bed should exceed the width of the road structure (including the width of the curb foundation) by no less than 10cm on each side.