ABSTRACT
Figure 15.1 provides an overview of the information ow for a generic microsimulation model. We can see that there are two basic inputs: supply (box A) and demand (box B). e supply consists of (1) the physical attributes of the network and (2) the operating strategies of the transportation agency. An example of the former would be the fact that a given intersection has a trac signal present. An example of the latter is illustrated by that all trac signals in the simulation model operate according to the city’s timing plan. Note that the supply is typically under the direct control of the decision makers in charge of the transportation network. For example, they can add more roads, expand lanes, add transit, or change signal timing plans in the hopes of improving performance at an intersection, along a particular roadway, across a corridor, or at the system level. In contrast, the decision makers may exert considerable or almost no control over demand, depending on the situation. For example, airlines choose their prices and can manage demand by varying their fares. In contrast, highway authorities have limited ability to change prices on freeways, and consequently, they have to use other approaches, such as ramp metering or high-occupancy lanes.
