Systematic Investigation of Variability due to Random Simulation Error in an Activity-Based Microsimulation Forecasting Model

2003 ◽  
Vol 1831 (1) ◽  
pp. 76-88 ◽  
Author(s):  
Joe Castiglione ◽  
Joel Freedman ◽  
Mark Bradley
Keyword(s):  
Travel Demand ◽  
Mode Choice ◽  
Demand Forecasting ◽  
Time Of Day ◽  
Model System ◽  
Destination Choice ◽  
Random Numbers ◽  
Microsimulation Model ◽  
Random Simulation ◽  
Simulation Error

A key difference between stochastic microsimulation models and more traditional forms of travel demand forecasting models is that micro-simulation-based forecasts change each time the sequence of random numbers used to simulate choices is varied. To address practitioners’ concerns about this variation, a common approach is to run the microsimulation model several times and average the results. The question then becomes: What is the minimum number of runs required to reach a true average state for a given set of model results? This issue was investigated by means of a systematic experiment with the San Francisco model, a microsimulation model system used in actual planning applications since 2000. The system contains models of vehicle availability, day pattern choice, tour time-of-day choice, destination choice, and mode choice. To investigate the variability of the forecasts of this system due to random simulation error, the model system was run 100 times, each time changing only the sequence of random numbers used to simulate individual choices from the logit model probabilities. The extent of random variability in the model results is reported as a function of two factors: ( a) the type of model (vehicle availability, tour generation, destination choice, or mode choice); and ( b) the level of geographic detail—transit at the analysis zone level, neighborhood level, or countywide level. For each combination of these factors, it is shown graphically how quickly the mean values of key output variables converge toward a stable value as the number of simulation runs increases.

A Combined Disaggregate Model System for Travel Demand Forecasting

1994 ◽  
Vol 27 (12) ◽  
pp. 507-512
Author(s):  
Liang Su ◽  
Naojiro Aoshima ◽  
Shogo Kawakami
Keyword(s):  
Travel Demand ◽  
Demand Forecasting ◽  
Model System ◽  
Travel Demand Forecasting ◽  
Disaggregate Model

scholarly journals Agent-Based Simulation to Improve Policy Sensitivity of Trip-Based Models

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Rolf Moeckel ◽  
Nico Kuehnel ◽  
Carlos Llorca ◽  
Ana Tsui Moreno ◽  
Hema Rayaprolu
Keyword(s):  
Travel Demand ◽  
Time Budget ◽  
Time Of Day ◽  
Destination Choice ◽  
Trip Generation ◽  
Demand Model ◽  
Agent Based ◽  
Travel Mode Choice ◽  
Travel Time Budget ◽  
Aggregate Nature

The most common travel demand model type is the trip-based model, despite major shortcomings due to its aggregate nature. Activity-based models overcome many of the limitations of the trip-based model, but implementing and calibrating an activity-based model is labor-intensive and running an activity-based model often takes long runtimes. This paper proposes a hybrid called MITO (Microsimulation Transport Orchestrator) that overcomes some of the limitations of trip-based models, yet is easier to implement than an activity-based model. MITO uses microsimulation to simulate each household and person individually. After trip generation, the travel time budget in minutes is calculated for every household. This budget influences destination choice; i.e., people who spent a lot of time commuting are less likely to do much other travel, while people who telecommute might compensate by additional discretionary travel. Mode choice uses a nested logit model, and time-of-day choice schedules trips in 1-minute intervals. Three case studies demonstrate how individuals may be traced through the entire model system from trip generation to the assignment.

Generation of Synthetic Daily Activity-Travel Patterns

1997 ◽  
Vol 1607 (1) ◽  
pp. 154-162 ◽  
Author(s):  
Ryuichi Kitamura ◽  
Cynthia Chen ◽  
Ram M. Pendyala
Keyword(s):  
Daily Activity ◽  
Travel Demand ◽  
Demand Forecasting ◽  
Multinomial Logit Model ◽  
Time Of Day ◽  
Travel Patterns ◽  
Activity Type ◽  
Individual Activity ◽  
Sequential Approach ◽  
Data Set

Microsimulation approaches to travel demand forecasting are gaining increased attention because of their ability to replicate the multitude of factors underlying individual travel behavior. The implementation of microsimulation approaches usually entails the generation of synthetic households and their associated activity-travel patterns to achieve forecasts with desired levels of accuracy. A sequential approach to generating synthetic daily individual activity-travel patterns was developed. The sequential approach decomposes the entire daily activity-travel pattern into various components, namely, activity type, activity duration, activity location, work location, and mode choice and transition. The sequential modeling approach offers practicality, provides a sound behavioral basis, and accurately represents an individual’s activity-travel patterns. In the proposed system each component may be estimated as a multinomial logit model. Models are specified to reflect potential associations between individual activity-travel choices and such factors as time of day, socioeconomic characteristics, and history dependence. As an example results for activity type choice models estimated and validated with the 1990 Southern California Association of Governments travel diary data set are provided. The validation results indicate that the predicted pattern of activity choices conforms with observed choices by time of day. Thus, realistic daily activity-travel patterns, which are requisites for microsimulation approaches, can be generated for synthetic households in a practical manner.

Travel Demand Modeling and Conformity Determination: Atlanta Regional Commission Case Study

2002 ◽  
Vol 1817 (1) ◽  
pp. 172-176 ◽  
Author(s):  
Guy Rousseau ◽  
Tracy Clymer
Keyword(s):  
Land Use ◽  
Travel Demand ◽  
Mode Choice ◽  
Time Of Day ◽  
Traffic Model ◽  
Demand Model ◽  
Primary Input ◽  
Land Use Model ◽  
Home Based ◽  
Travel Demand Model

The Atlanta Regional Commission (ARC) regional travel demand model is described as it relates to its link-based emissions postprocessor. In addition to conformity determination, an overview of other elements is given. The transit networks include the walk and highway access links. Trip generation addresses trip production, trip attraction, reconciliation of productions and attractions, and special adjustments made for Hartsfield Atlanta International Airport. Trip distribution includes the application of the composite impedance variable. In the mode choice model, home-based work uses a logit function, whereas nonwork uses information from the home-based work to estimate modal shares. Traffic assignment includes preparation of time-of-day assignments. The model assigns single-occupancy vehicles, high-occupancy vehicles, and trucks by using separate trip tables. The procedures can accept or prohibit each of the three types of vehicles from each highway lane. Feedback between the land use model and the traffic model is accounted for via composite impedances generated by the traffic model and is a primary input to the land use model DRAM/EMPAL. The land use model is based on census tract geography, whereas the travel demand model is based on traffic analysis zones that are subareas within census tracts. The ARC model has extended the state of the practice by using the log sum variable from mode choice as the impedance measure rather than the standard highway time. This change means that the model is sensitive not only to highway travel time but also to highway and transit costs.

scholarly journals What Matters Most in Transportation Demand Model Specifications: A Comparison of Outputs in a Mid-size Network

2015 ◽  
Author(s):  
T. Donna Chen ◽  
Kara Kockelman ◽  
Yong Zhao
Keyword(s):  
Travel Demand ◽  
Choice Model ◽  
Mode Choice ◽  
Demographic Data ◽  
Time Of Day ◽  
Demand Model ◽  
Land Use Patterns ◽  
Transportation Demand ◽  
Step Model ◽  
The Impact

This paper examines the impact of travel demand modeling (TDM) disaggregation techniques in the context of medium-sized communities. Specific TDM improvement strategies are evaluated for predictive power and flexibility with case studies based on the Tyler, Texas, network. Results suggest that adding time-of-day disaggregation, particularly in conjunction with multi-class assignment, to a basic TDM framework has the most significant impacts on outputs. Other strategies shown to impact outputs include adding a logit mode choice model and incorporating a congestion feedback loop. For resource-constrained communities, these results show how model output and flexibility vary for different settings and scenarios.BACKGROUND Transportation directly provides for the mobility of people and goods, while influencing land use patterns and economic activity, which in turn affect air quality, social equity, and investment decisions. Driven by the need to forecast future transportation demand and system performance, Manheim (1979) and Florian et al. (1988) introduced a transportation analysis framework for traffic forecasting using aggregated data that provide the basis for what is known as the four-step model: a process involving trip generation, then trip distribution and mode choice, followed by route choice. Aggregating demographic data at the zone level, the four-step model generates trip productions based on socioeconomic data (e.g., household counts by income and size) and trip attractions primarily based on jobs counts. The model then proportionally distributes trips between each origin and destination (OD) zone pair based on competing travel attractions and impedances, under the assumption that OD pairings with higher travel costs draw fewer trips. Trips between each OD pair are split among a variety of transportation modes, allocating trips to private vehicle, transit, or other

Practical Approach to Model Trip Chaining

1998 ◽  
Vol 1645 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Yoram Shiftan
Keyword(s):  
Travel Demand ◽  
Choice Model ◽  
Academic Research ◽  
Household Survey ◽  
Model System ◽  
Destination Choice ◽  
Type Model ◽  
Trip Chaining ◽  
Model Components ◽  
At Home

The need to model trip chaining has been discussed widely in the travel demand literature, but new approaches generally have been limited to academic research. Trip chaining was modeled in an actual urban area model. The model was developed for Boise, Idaho, on the basis of a household survey of 1,600 households. For this model, a tour was defined as a sequence of trip segments that start at home and end at home. The model distinguishes between two main types of tours: A tour that includes one or more work destinations is defined as a work-related tour (WRT); all other tours are defined as nonwork-related tours (NWRT). A model system was developed by assuming the hierarchy of the model components. The highest-level model estimates auto ownership for the household. On the basis of auto ownership, the frequency of WRT is estimated, and on the basis of the frequency of WRT, the frequency of NWRT is modeled. These three model components produce the number of WRT and NWRT for each household. All subsequent models are estimated at the tour level. The WRT model system includes work destination choice model, tour type model including the number of stops on the way to and from work and midday trips, and secondary destination choice model for all nonwork destinations. The NWRT model was developed in the same way with some structural differences.

Florida Activity Mobility Simulator

2005 ◽  
Vol 1921 (1) ◽  
pp. 123-130 ◽  
Author(s):  
Ram M. Pendyala ◽  
Ryuichi Kitamura ◽  
Akira Kikuchi ◽  
Toshiyuki Yamamoto ◽  
Satoshi Fujii
Keyword(s):  
Travel Demand ◽  
Demand Forecasting ◽  
Model Development ◽  
Model System ◽  
Model Systems ◽  
Development Effort ◽  
Transportation Demand ◽  
New Era ◽  
System A ◽  
Preliminary Validation

The development of modeling systems for activity-based travel demand ushers in a new era in transportation demand forecasting and planning. A comprehensive multimodal activity-based system for forecasting travel demand was developed for implementation in Florida and resulted in the Florida Activity Mobility Simulator (FAMOS). Two main modules compose the FAMOS microsimulation model system for modeling activity–travel patterns of individuals: the Household Attributes Generation System and the Prism-Constrained Activity–Travel Simulator. FAMOS was developed and estimated with household activity and travel data collected in southeast Florida in 2000. Results of the model development effort are promising and demonstrate the applicability of activity-based model systems in travel demand forecasting. An overview of the model system, a description of its features and capabilities, and preliminary validation results are provided.

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