Uses of Travel Demand Models Beyond the MTP

Janie Temple Transportation Planning and Programming Division

October 12, 2011

Presentation Outline

What is a Travel Demand Model?

Cautionary notes on using models Typical Uses Emerging Uses Innovative Uses

What are Travel Demand Models

Travel demand models (TDMs) are

developed to simulate actual travel patterns and existing demand conditions in an urban area or region.

Travel Demand Modeling

Forecasts are used to develop

information to evaluate the effects that known and projected changes in socioeconomic conditions may have on the demand for travel on the urban area's major roadway and transit systems.

The Travel Demand Modeling Process

Trip generation

Trip Distribution

Mode Choice Traffic Assignment

Notes on using TDMs - Application Consistency

Model construct must be consistent with The requirements of the analysis. For example, sketch planning models are appropriate for analyses to evaluate and select specific transportation alternatives for further analysis but would be inconsistent with the analysis requirements for estimating toll revenue.

Application Consistency

Consistency between model framework and analysis requirements is necessary to ensure that the model is not used in a way that is inconsistent with the theory on which it is founded.

Notes on using TDMs - Reasonableness Checks

Reasonableness checks should be part of model development and analyses standard practice because there are many opportunities for introducing erroneous data, omitting information, or misunderstanding models and analyses.

Reasonableness Checks

Input data Calibration/Validation data Evaluate each model step results Evaluate final model results Sensitivity testing

Notes on using TDMs - Benefits

Known input and analysis parameters Allows comparison of alternatives Baseline and alternatives can be easily

compared Results can be replicated Results can be compared to other data

sources such as Census data

Typical Uses of TDMs

TDM output is used by TxDOT, MPOs, and local governments to:

Develop or update the metropolitan

transportation plan Program projects for additional study Rank projects for the Transportation

Improvement Program Emissions analysis in non-attainment areas

Typical Uses of TDMs

Evaluate system improvements Identify system deficiencies Conduct Alternative analysis Supports future design level traffic

development

Typical Uses of TDMs – GIS Databases

The model input data consists of three primary databases for both base and forecast years.

Network database Traffic analysis zone database Demographic database

Using TDM Database Road Network in Tyler, Texas

Using TDM Databases – Employment in Tyler, Texas

Using TDM Results – Travel Patterns in Tyler, Texas

Using TDM Results – Volume to Capacity Ratios in Tyler,

Texas

Emerging Uses of TDMs

Linking planning and environmental Traffic operations analyses HOV Analysis Toll and HOT analyses Transit analyses

– New/Small Starts Applications Needs based analyses

– TMMP/TUMP

Planning and Environmental

TDMs may be used for planning and environmental linkages: Statewide Implementation Plan development Conformity emissions analyses Air quality studies and analyses

– TCM evaluations – Hot spot analyses – Mobile Source Air Toxics analyses

Planning and Environmental

Indirect and cumulative impact (ICI)

studies - used at least as baseline Socioeconomic analyses

(demographics and land use) - used at least as baseline

Regional toll analyses

Planning and Environmental

Alternatives analyses (traffic

redirection studies) Land use information may also be

used to help assess water quality and biological impacts

Need and purpose

Operational Analysis

TDMs – Macro scale – Regional travel

patterns – 24 hr/daily demand – Typical weekday

travel – Simplified network – Link volume output

Simulation Models – Micro scale – Addresses dynamic

aspects of traffic – Incremental

demand – Detailed network – Capacity restrained – Provides network

delay

Operational Analysis

TDM and simulation models are used together to accomplish operational Analysis. Simulation model inputs include: The regional TDM Local travel survey data

Innovative Uses of TDMs

Evaluate alternate growth scenarios Evaluate major transit projects Evaluate major land use changes Link to land use models Link to economic models Link to the Statewide Analysis Model Link to other freight or truck models

Innovative Uses of TDMs

Commuter rail studies using planning models and the Statewide Analysis Model

Evaluate hurricane evacuations Evaluate impacts of floods Evaluate smart growth impacts Evaluate alternate funding scenarios

Conclusions

Travel demand models are powerful tools

Travel demand models can be utilized in transportation planning in innovative ways

Understanding the model is critical to producing effective analyses

If you need additional information

For questions about the development

or uses of the travel demand model, please contact one of the following people:

Contact Information

Janie Temple (512) 486-5107

jtempl1@dot.state.tx.us

Greg Lancaster (512) 486-5126

glancas@dot.state.tx.us