TransCAD, Visum, and Cube are three examples of software that are used for travel demand modeling. These types of tools are typically GIS-based planning-stage tools used for travel demand modeling. Inputs include analysis zones and network of links (roadways and zone connectors). Most models are based on static traffic assignment, with static travel times for calculating the shortest path. Analysis zones include attributes such as land use, population, trip origins and destinations by mode, and employment data. Links include attributes such as facility type, number of lanes, posted speeds, capacity, distance, and travel time. Analysis follows the four-step model to output projected traffic volumes. When using TDMs, tool selection is based on model availability (i.e., if the TDM used was developed in Cube, then it is recommended that Cube is used as the analysis tool for the project). The content in this chapter focuses on TDM outputs, not on the development of TDMs. Typical outputs for a TDM are the Vehicle Miles Traveled (VMT), Vehicles Hours Traveled (VHT), Vehicle Hours of Delay, volume-to-capacity ratio, and speed.

A mesoscopic simulation model that uses dynamic traffic assignment (DTA) that is used for planning- and schematic-level projects. DynusT is a stochastic tool that uses the HCM fundamentals. It is a hybrid of microsimulation models and HCM-based models because it can model traffic flows and individual vehicles at intersections. It considers saturated and unsaturated conditions, capturing queues and diverted traffic. It also calculates shortest paths based on experienced travel delay

HCS is a Preliminary Schematics-stage tool used to evaluate uninterrupted flow (freeway) and interrupted flow (urban and rural) facilities. HCS performs the HCM equations/operations and includes methodologies for vehicle and non-vehicle (pedestrian, bicycle, transit) modes. HCS inputs and outputs vary by facility and mode; inputs include volume, roadway, and signal timing parameters. HCS outputs include traffic operations MOEs LOS, delay, queue lengths, facility travel speed, etc.). HCS reports static output by intersection or roadway segment. HCS results are most reliable when typical geometric locations are analyzed at locations with traffic volumes under capacity (undersaturated conditions). HCM/HCS is traditionally used for undersaturated conditions and rural facilities. HCS can be calibrated to local conditions by adjusting default inputs.

Synchro is a Preliminary Schematics-stage tool used to evaluate urban roadways and rural/urban intersections. Synchro performs the HCM calculations and includes proprietary equations particularly useful for optimizing signal timing parameters along signalized arterials within a static model. Synchro inputs include volume, roadway, and signal timing parameters. Bing maps are embedded in Synchro and Environmental Systems Research Institute (ESRI) shapefiles (or other georeferenced files/aerials) and can be imported into Synchro such that links/nodes are mapped correctly. Synchro can be calibrated to local conditions by adjusting default inputs.

Synchro outputs include traffic operations MOEs and environmental MOEs (fuel consumption and emissions). Synchro reports the HCM calculation results or Synchro static model percentile delay results for each location or network. The HCM results can be reported for intersection analyses, except for signal timing optimization projects. The Synchro proprietary delay calculations employ a percentile delay method, where delays are calculated for the 10th, 30th, 50th, 70th, and 90th percentile traffic volumes and then averaged to provide the reported delay values. Additionally, Synchro is capable of multi-file comparisons and TIA reporting.

Signalized and unsignalized intersection design and research aid (SIDRA) is a Preliminary Schematics-stage tool used to evaluate intersections, mainly roundabouts. SIDRA inputs include volume and roadway parameters. SIDRA outputs include LOS and delay reported by lane. SIDRA provides outputs for each location.

FREEVAL is a Planning-stage tool that is based on the HCM methodology and used to perform a capacity analysis for undersaturated and oversaturated conditions. In addition to a basic capacity analysis, it performs work zone impact analysis, managed lane analysis, and travel time reliability analysis. FREEVAL can be downloaded from the FREEVAL website, which also has links to user guides, instructive videos, and links to other resources.

Vissim is a tool used to evaluate uninterrupted and interrupted facilities. Vissim inputs need a more granular level of detail than macroscopic or mesoscopic models. Vissim is a microsimulation modeling program that simulates the movements of individual vehicles throughout a predefined network. A sketchlevel or macroscopic modeling tool aggregates vehicle behaviors between decision points. Vissim, by contrast, tracks every movement that every vehicle makes from the moment it enters the network until the moment it exits the network.

Vissim inputs include volume, roadway, and signal timing parameters. Vissim outputs include traffic and environmental MOEs. Vissim accounts for randomness and factors not included in the HCM calculations, including driver behavior and how delays in one part of the network impact every other part of the network. This makes Vissim more accurate, particularly when evaluating oversaturated conditions. Vissim reports simulation output by location. Vissim simulations can be exported as video files to demonstrate the conditions to expect in the field. Vissim is typically used to analyze complicated or unusual geometry, oversaturated conditions, alternative intersections, and complex urban facilities/networks.

Vissim (or an alternative microsimulation tool) is often used to analyze locations with the following characteristics:

CORSIM is a Final/Approved Schematics and Design-stage tool used to evaluate complex or oversaturated freeway and urban roadway facilities. CORSIM is a Microsimulation (Microscopic) traffic simulation that models freeways, highways, networks, including segments, weaves, merges/diverges, and unsignalized and signalized intersections. CORSIM inputs are similar to Preliminary Schematics-stage tools, with the addition of user-defined driver characteristics (dwell time, driver familiarity, etc.). CORSIM outputs include traffic and environmental MOEs.

SimTraffic, a companion tool for Synchro, is a microscopic and Final/Approved Schematics and Design-stage tool used to evaluate intersections and networks. SimTraffic inputs are similar to Preliminary Schematic-stage tools, with the addition of driver behavior parameters (deceleration rates, reaction time, gap acceptance factor, etc.). Driver behavior parameters are modified for each of 10 driver types. As vehicles are added to the simulation, they are randomly assigned a driver type. SimTraffic outputs include traffic and environmental MOEs. SimTraffic simulations can be exported as video files. Typical applications of SimTraffic include analyzing signalized and unsignalized intersections.