What is the allowable tolerance for the completed thickness of the base for crushed stone bases and sub-bases?

The correct answer, which indicates an allowable tolerance of ± 6mm for the completed thickness of the base for crushed stone bases and sub-bases, reflects industry standards aimed at ensuring proper construction quality and structural integrity. This tolerance is critical in highway and road construction, where variations beyond specified limits can lead to issues such as uneven surfaces, compromised load distribution, and increased wear on pavement materials over time.

A tolerance of ± 6mm illustrates a commitment to precision in the construction process. This specification helps maintain consistency in the base layer, which is essential for the structural performance of the roadway or any paved surface built upon it. The narrower tolerance compared to other choices emphasizes the need for accuracy in thickness to reduce future maintenance costs and enhance durability.

In practice, ensuring that thickness deviates no more than 6mm from the specified design can significantly impact the overall performance and longevity of the pavement, ensuring a safer and more reliable surface for vehicles.