Travel Demand Forecasting: Parameters and Techniques (2012) / Chapter Skim
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Pages 89-99
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From page 89... ...
is the product of a TRB study, funded by FHWA, FTA, and the Office of the Secretary of Transportation, to determine the national state of practice in metropolitan area travel demand forecasting and to recommend improvements (Committee for Determination of the State of the Practice in Metropolitan Area Travel Forecasting, 2007)
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Home HomeWork Shop Home HomeWork HomeShop Figure 6.1. Temporal substitution of trips.
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These decisions determine the generation and scheduling of trips. Hence, determining the impact of travel demand management policies on time use behavior is an important precursor step to assessing the impact of such policies on individual travel behavior.
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Population synthesis; 2. Long-term choice models; and 3.
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Subsequent to the determination of long-term choices, the synthetic population of households and individuals is "processed" through the activity-based travel model system, as discussed in more detail in the following sections. 6.2.2 Generic Structure of Activity-Based Systems Activity-based model systems used in practice typically consist of a series of utility maximization-based discrete choice models (i.e., multinomial logit and nested logit models)
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Transportation network data needed in activity models are similar to data used in trip-based models and typically include highway network data, transit network data, and nonmotorized mode data. The transportation system performance data should be of high quality, with time-varying LOS characteristics (in-vehicle, out-of-vehicle, access, egress, and wait times)
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are required for past years and existing "future" years. In this regard, it is important that the regional planning agencies store and document the land use data and transportation network data of past and existing "future" years.
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operational activity-based travel demand models treat the longer-term choices concerning the housing (such as residential tenure, housing type, and residential location) , vehicle ownership, and employment choices (such as enter/exit labor market and employment type)
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as well as the spatial path assignment as input, and outputs the spatial-temporal trajectories of vehicles as well as travel times. The time-dependent shortest path routing algorithms and path assignment models take the spatiotemporal vehicle trajectories and travel times as input, and output the spatial path assignment of vehicles.
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From page 98... ...
Person tours generated by the activity-based model that are fully or partially made via transit can have their transit paths simulated individually. This individual simulation requires the specification of all transit vehicle runs and stops and the assigning of passenger trips to these runs and stops, along with their walk and auto access and egress components.
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From page 99... ...
individual of the study area using a microsimulation implementation that provides activity-travel outputs that look similar to survey data and can allow analysis of a wide range of policies on specific sociodemographic segments. Activity-based travel models are increasingly being adopted by the larger MPOs in the country and offer a more comprehensive and potentially more accurate assessment of policies to enhance mobility and reduce emissions.
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