28.7. Pavement Thickness Design Charts

Try these first

1. 1.

   What does CBR stand for?

   Hint

   Think about what CBR measures.

2. 2.

   Which chart do you use for traffic loads of 5 msa?

   Hint

   Recall the traffic ranges defined earlier.

3. 3.

   The CBR is a measure of:

   • Pavement thickness
   • Subgrade strength
   • Traffic load

   Hint

   Think about what the CBR test evaluates.

4. 4.

   Using Chart 2 is necessary for traffic loads of:

   • True
   • False

   Hint

   Recall which traffic loads correspond to which chart.

5. 5.

   A new highway is expected to carry 100 msa with an average subgrade CBR of 5%. Calculate the required pavement thickness using the appropriate chart and discuss any potential issues with this design.

   Hint

   Look carefully at the upper limits of traffic loads mentioned in the charts.

6. 6.

   If you see a failure in the pavement structure, how would you assess whether the thickness was appropriate? Consider factors like CBR, traffic predictions, and material quality in your response.

   Hint

   Consider the interplay of design assumptions against actual conditions observed after construction.