Monte Carlo Variability

The following controls, located on the Input -> Simulation Parameters Page, are used to specify Monte Carlo variability parameters associated with the Mechanistic-Empirical simulation.

Selecting Monte Carlo for the Simulation Type will enable the following set of controls.

In Deterministic mode, the values (for thickness and modulus) entered in the Pavement Structure grid will be used in the simulation. These values may either represent the values at a specific point or the mean values over a section of pavement. The simulation will predict the permanent deformation and the damage of each layer in the pavement, but the roughness cannot be calculated as this is a function of the variability.

In Monte Carlo mode, many simulations are performed on the pavement structure using random values from a distribution of values for several input data items, such as thickness and and modulus. The number of simulations is specified below. Monte Carlo takes into account within project construction variability.

Monte Carlo Variability data items:

•No. of simulations - this sets the number of simulations to perform. The default is 10 but more are normally needed to achieve a 95% or greater reliability for rutting and cracking.

•Construction variability - select this item to include construction variability. The default is to include construction variability in the simulation.

•Layer variability parameters - the coefficient of variation for thickness (CoV Thick) and standard deviation for the modulus (Sdf Modulus) are shown for each layer from the Material Library. You may make changes to these values. When a project is created from a CalBack import, the "CoV Thick" is set to zero and the value for "Sdf Modulus" is computed from the modulus points for a section defined in the import file.

The question mark in the blue circle in the upper-right of the control group allows you to get help on the controls (this topic).