It takes roughly 20,000 passes of the sedan to cause the same amount of same amount of damage as one pass of a tractor-trailer. In these scenarios, the design ESALs will be predetermined. This is usually based on the expected traffic mix. Reference ASCE and ICPI Tech Spec 4 to calculate the appropriate ESAL rating to a design.
Pedestrian or Light Vehicular Loads
Intermediate Vehicular Loads
Heavy Vehicular Loads or Weak Soil
Choosing a reliability ratio is based on the amount of uncertainty on the expected traffic loads over the life the pavement, the soil type or ability of the soil to support the pavement especially if saturated and weakened from wet weather. A reliability ratio of 75% is typical for low speed municipal roadways.