Simulation Type

The following controls, located on the Input -> Simulation Parameters Page, are used to specify the type of Mechanistic-Empirical simulation to perform for the pavement project.

CalME has two types of Mechanistic-Empirical (ME) simulations to select from:

•Deterministic - a single simulation is performed on the design using the median inputs to estimate the median performance

•Monte Carlo - multiple simulations are performed in parallel on the design to estimate the distribution of its performance. Each simulation represents a likely as-built slice of the given design after accounting for the construction variability. The number of simulations is specified in the Monte Carlo Variability parameter section. For more details on the role of Monte Carlo simulations in CalME please go to accounting for uncertainties.

In general, Deterministic simulations are performed to get close to the optimal design, and Monte Carlo simulations are performed to determine the optimal design, often after slightly thickening the structure. For details on how this process works see topic Typical Design Process.

The default number of simulations for Monte Carlo runs is set at 60, which is high enough to confirm whether a design to have minimum 95% reliability.

The amount of CalME runtime required to perform the Monte Carlo analysis is directly dependent on the number of simulations and the simulation duration (set to Design Life by default). Using a four-layer structure as an example, the following are runtimes are:

•Simulation duration = 20 yrs                    Number of simulations = 10                    19 seconds

•Simulation duration = 20 yrs                    Number of simulations = 60                    64 seconds

•Simulation duration = 40 yrs                    Number of simulations = 60                    121 seconds

This indicated that a 20 year design typically needs one minute to run, while a 40 year design needs two minutes.

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).