Transportation Statistics and Microsimulation

6    ◾    Transportation Statistics and Microsimulation

disciplines, including pavement engineering, that are not necessarily appli-

cable to transportation systems engineering. For example, consider an

engineer who is interested in the various factors that aect skid resistance

and the relationship to crash rate. From an ethical standpoint, she cannot

place various types of pavement surfacing on dierent sections of high-

way, observe what types of accidents occur, and then choose the best type

of pavement based on the empirical accident results. Instead, most trans-

portation studies are observational in nature, and as a result, the statisti ...