For concrete roads, what is the maximum allowable slope of the road shoulder from the edge of the road carriageway?

The maximum allowable slope of the road shoulder from the edge of the road carriageway is typically designed to facilitate proper drainage and ensure the safety of vehicles. A slope in the range of 1.5% to 2.0% is optimal because it allows water to run off effectively, preventing pooling or flooding on the shoulder, which could create hazardous conditions for drivers.

Steeper slopes can lead to erosion and may pose difficulties for vehicles that may leave the roadway, while slopes that are too gentle may not drain water effectively, risking accumulation and creating a slippery surface. Thus, the range of 1.5% to 2.0% strikes a balance between adequate drainage and maintaining shoulder stability and safety, making it the standard practice for concrete road design.