Recent itsirvine_casa_rw items

The Activity-Based Approach

Mon, 17 Nov 2008 00:00:00 +0000

What is the activity-based approach (ABA) and how does it differ from the conventional trip-based model of travel behavior? From where has the activity approach evolved, what is its current status, and what are its potential applications in transportation forecasting and policy analysis. What have been the contributions of activity-based approaches to understanding travel behavior?

The conventional trip-based model of travel demand forecasting (see Chapters 2 and 3) has always lacked a valid representation of underlying travel behavior. This model, commonly referred to as the four-step model (FSM), was developed to evaluate the impact of capital-intensive infrastructure investment projects during a period where rapid increases in transportation supply were arguably accommodating, if not directing, the growth in population and economic activity of the post-war boom. As long as the institutional environment and available resources supported this policy, trip-based models...

The Four Step Model

Mon, 17 Nov 2008 00:00:00 +0000

The history of demand modeling for person travel has been dominated by the modeling approach that has come to be referred to as the four step model (FSM) (see Chapter 2). Travel, always viewed in theory as derived from the demand for activity participation, in practice has been modeled with trip-based rather than activity-based methods (as presented in Chapter 4). Trip origin-destination (O-D) rather than activity surveys form the principle database. The influence of activity characteristics decreases, and that of trip characteristics increases, as the conventional forecasting sequence proceeds. The application of this modeling approach is near universal, as in large measure are its criticisms (these inadequacies are well documented, e.g., by McNally and Recker (1986)). The current FSM might best be viewed in two stages. In the first stage, various characteristics of the traveler and the land use - activity system (and to a varying degree, the transportation system) are "evaluated,...

Land Use Influences on Trip Chaining in Portland, Oregon

Mon, 17 Nov 2008 00:00:00 +0000

This paper examines the nature of land use based substitution effects on travel modes, identified by Greenwald, examining the direct impact of land uses inducing trip-making behaviors. These impacts are analyzed in the context of trip chaining, defined here as consolidating two or more non-home activities in a single departure from home. The findings suggest rather than strictly promoting one type of transportation over another, the regional impact of localized urban design practices is to consolidate trip making behavior closer to the home. As such, urban design “carrots” must be complemented with policy “sticks” in order to promote true exchanges of travel modes.

Impact Of Real-World Driving Characteristics On Vehicular Emissions

Tue, 13 Feb 2007 00:00:00 +0000

With increase in traffic volume and change in travel related characteristics, vehicular emissions and energy consumption have increased significantly since two decades in India. Current models are not capable of estimating vehicular emissions accurately due to inadequate representation of real-world driving. The focus of this paper is to understand the level of Indian Driving cycle (IDC) in representing the real-world driving and to assess the impact of real-world driving on vehicular emissions.

The study has revealed that IDC does not represent the real-world driving. Irrespective of road classes, about 30% of time is spent below 20 km/hr and the speed too exceeds IDC’s maximum limit of 42 km/hr. Emissions are estimated for different driving patterns using International Vehicle Emission (IVE) model. Emission rates vary significantly from one class of road to another and the largest effect is on local streets.

An Empirical Investigation of the Dynamic Processes on Activity Scheduling and Trip Chaining

Tue, 13 Feb 2007 00:00:00 +0000

The dynamic process of how individuals organize their activities and travel is often termed activity scheduling. Investigation of the dynamic processes has been the interest of transportation researchers in the past decade, because of its relevance to the effectiveness of congestion management and intelligent transportation systems. To empirically examine this process, a computerized survey instrument was developed to collect household activity scheduling data. The instrument is unique in that it records the evolution of activity schedules from intentions to final outcomes for a weekly period.

This paper summarizes the investigation on the dynamic processes of activity scheduling and trip chaining based on data collected from a pilot study of the instrument. With the data, ordered logit models are applied to identify factors that are related to the scheduling horizon of activities. Results of the empirical analyses show that activities of shorter duration were more likely...

Estimation of Vehicular Emissions by Capturing Traffic Variations

Tue, 13 Feb 2007 00:00:00 +0000

Increase in traffic volumes and changes in travel-related characteristics increase vehicular emissions significantly. It is difficult, however, to accurately estimate emissions with current practice because of the reliance on travel forecasting models that are based on steady state hourly averages and, thus, are incapable of capturing the effects of traffic variations in the transportation network. This paper proposes an intermediate model component that can provide better estimates of link speeds by considering a set of Emission Specific Characteristics (ESC) for each link. The intermediate model is developed using multiple linear regression; it is then calibrated, validated, and evaluated using a microscopic traffic simulation model. The improved link speed data can then be used to provide better estimates of emissions. The evaluation results show that the proposed emission estimation method performs better than current practice and is capable of estimating time-dependent...

TRACER: In-Vehicle, GPS-Based Wireless Technology for Traffic Surveillance and Management.

Wed, 7 Feb 2007 00:00:00 +0000

The fundamental principle of intelligent transportation systems is to match the complexity of travel demands with advanced supply-side analysis, evaluation, management, and control strategies. A fundamental limitation is the lack of basic knowledge of travel demands at the network level. Modeling and sensor technology is primarily limited to aggregrate parameters or micro-simluations based on aggregate distributions of behavior. Global Positioning Systems (GPS) are one of several available technologies which allow individual vehicle trajectories to be recorded and analyzed. Potential applications of GPS which are relevant to the ATMS Testbed are implemented in probe vehicles to deliver real-time performance data to complement loop and other sensor data and implementation in vehicles from sampled households to record route choice behavior. An Extensible GPS-based in-vehicle Data Collection Unit (EDCU)has been designed, tested, and applied in selected field tests. Each...

Comparing the Influence of Land Use on Nonwork Trip Generation and Vehicle Distance Traveled: An Analysis using Travel Diary Data.

Wed, 7 Feb 2007 00:00:00 +0000

This study uses two-day travel diary data to examine whether land use matters more for an individual's total vehicle miles traveled (VMT). More specifically, sociodemographic, land use, and street connectivity variables are used to estimate nonwork trip frequency and nonwork vehicle miles traveled via ordered probit and ordinary least-squares regression models. We compare standardized coefficients of the models and conclude that: (1) the influence of land use variables is similar in both the trip generation and VMT regressions; and (2) income is the primary determinant of both trip frequency and VMT, but that land use exerts an influence that is on par with other sociodemographic characteristics after the primary role of income is considered.

A Simultaneous Model of Household Activity Participation and Trip Chain Generation

Wed, 16 Apr 2003 00:00:00 +0000

A trip generation model has been developed using a time-use perspective, in which trips are generated in conjunction with out-of-home activities, and time spent traveling is another component of overall time use. The model jointly forecasts three sets of endogeneous variables -- (1) activity participation and (2)travel time (together making up total out-of-home time use), and (3)trip generation -- as a function of household characteristics and accessibility indices. It is estimated with data from the Portland, Oregon 1994 Activity and Travel Survey. Results show that the basic model,which has ten endogeneous time use and trip generation variables and thirteen exogeneous variables, fits well, and all postulated relationships are upheld. Tests show that the basic model, which divides activities into work and nonwork, can be extended to a three-way breakdown of subsistence, discretionary and obligatory activities. The model can also capture the effects of in-home work on...

The Household Activity Pattern Problem: General Formulation and Solution

Mon, 14 Apr 2003 00:00:00 +0000

The household activity pattern problem of analyzing/predicting the optimal path of household members through time and space as they complete a prescribed agenda of out-of-home activities is posed as a variant of the pickup and delivery problem with time windows. The most general case of the model includes provision for vehicle transfer, selective activity participation and ridesharing options. A series of examples are solved using generic algorithms. The model is purported to remove existing barriers to the operationalization of activity-based approaches in travel behavior analysis.

GPS/GIS Technologies for Traffic Surveillance and Management: A Testbed Implementation Study

Mon, 14 Apr 2003 00:00:00 +0000

The fundamental principle of intelligent transportation systems is to match the complexity of travel demands with advanced supply-side analysis, evaluation, management and control strategies. A fundamental limitation is the lack of basic knowledge of travel demands at the network level. Modeling and sensor technology is primarily limited to aggregate parameters or micro-simulations based on aggregate distributions of behavior. Global positioning systems (GPS) are one of several available technologies that allow individual vehicle trajectories to be recorded and analyzed. Potential applications of GPS are implementation in probe vehicles to deliver real-time performance data to complement loop and other sensor data and implementation in vehicles from sampled households to record route choice behavior. A flexible GPS-based data collection unit has been designed which incorporates GPS, data logging capabilities, two-way wireless communications and a user interface in an embedded...

Evaluation of a Shared-Use Electric Vehicle Program: Integrating a Web-Based Survey with In-Vehicle Tracking

Mon, 14 Apr 2003 00:00:00 +0000

An experimental shared-use vehicle program in Irvine, California, is assigning 15 Toyota ecom electric vehicles to several public and private sector organizations who have identified a group of employees to utilize the vehicles in a shared-use mode. The primary goal of this experiment is to evaluate the potential of shared-use electric vehicles as a means of reducing urban traffic and vehicle emissions. The decision to travel with the shared-use vehicles can be understood only through examining the entire process of how participants schedule activites before, during and after shared-use vehicles become a travel option. To effectively evaluate performance of this prototype application, a novel data collection procedure is proposed that integrates GPS-based vehicle tracking and web-based travel survey technologies. The data collection process will occur in three stages: (1) before the vehicle-sharing program, (2) during the program and (3) after the program is completed....

How Households Use Different Types of Vehicles: A Structural Driver Allocation and Usage Model

Mon, 14 Apr 2003 00:00:00 +0000

The vehicle miles of travel for each vehicle in multi-vehicle households is modeled as a function of household characteristics, vehicle characteristics, and the matches of vehicle to driver in the satisfaction of travel desires. A structural equations model is developed in which principal driver characteristics, as well as vehicle miles of travel, are endogeneous. There are links between how each vehicle is used and who in the household is each vehicle's principal driver. Each vehicle's usage can then be expressed in reduced-form equations as a function of exogeneous household and vehicle type variables for forecasting purposes. The model is estimated on a 1993 sample of approximately 2000 multi-vehicle households in California.

Shopping without Travel or Travel without Shopping? An Investigation of Electronic Home Shopping

Fri, 11 Apr 2003 00:00:00 +0000

This study explores the growth of electronic home shopping in terms of likely transportation and communication interactions. Although opportunities exist to shop from home today, most consumers initiate travel trips to stores or markets. Widespread use of automobiles has facilitated the retailing configurations we know today but the development of new electronic networks could change this. This study establishes a baseline to explore shopping activities using two-day travel activity data from a large U.S. metropolitan area. It is found that people who telework from home today spend more time engaged in shopping activities than other workers. Potentially, their saved work travel is converted into new trips. In the future, saved shopping travel might be converted into other types of travel, and modeling results show that for busy working women, there is a latent demand for maintenance related activities. The study results suggest that electronic homw shopping will bring...

An Activity-Based Approach to Accessibility

Fri, 11 Apr 2003 00:00:00 +0000

This paper presents the initial formulation of an activity-based model structure to address deficiencies in traditional measures of individual accessibility and which incorporates temporal transference effects of alternative travel behaviors within a household to form an index sensitive to such effects. A network-based activity assignment protocol is developed for complex travel activity decisions within a household. The research incorporates routing, scheduling, household activity assignment and ride-sharing components into a hybrid model that explicitly captures the interactions between household members and integrates mode availability, ride-sharing behavior and time window constraints. In this approach, individual accessibility can be estimated and aggregated to reflect accessibility within a household under alternative transportation supply environments. Prior research on such accessibility approaches suggests that the proposed extensions can be applied to estimate...

An Assessment of the Interaction of the Land Use-Transportation System and Travel Behavior

Fri, 11 Apr 2003 00:00:00 +0000

This paper presents an empirical assessment of the interaction between the land-use transporttion system and travel behavior. A methodology is developed to identify a range of land-use transportation systems using a clustering technique with network and land use inputs. Twenty neighborhoods from Orange County, California, were considered in this process. Three groups, or themes, were found to best represent the neighborhoods in the sample area, one each associated with the conventional defition of neotraditional (TND) and planned unit development (PUD) neighborhoods, and one representing neighborhoods that blend characteristics of TND and PUD. Conventional and more complex measures of individual travel behavior were compared via an analysis of variance between the themes to identify significant differences, controlling for socio-economic differences. Research results included the development of a systematic methodology to identify a more explicit land use and transportation...

A Model of Household Demand for Activity Participation and Mobility

Fri, 11 Apr 2003 00:00:00 +0000

With modern multivariate statistical methods and activity-diary (time-use) data sets, it is possible to model household mobility decisions as being derived from decisions to participate in activities at various locations. We show how this can be accomplished by specifying activity participation by activity type and location as endogeneous variables, with a simple locational distinction of "at home" versus "out of home". The activity participation variables are then combined in a model system of simultaneous equations with variables that measure mobility demand: travel times by mode, household vehicle ownership and household vehicle utilization. We specify the model in terms of latent, multivariate normally distributed choice variables, and this treatment solves estimation problems associated with censored and ordinal observed endogeneous variables. The estimation method provides accurate goodness-of-fit evaluation and hypothesis testing. Results are shown from a model...

An Activity-Based Microsimulation Model for Travel Demand Forecasting

Fri, 11 Apr 2003 00:00:00 +0000

This paper summarizes the initial formulation of a micro-simulation model for activity-based travel demand forecasting that integrates household activities, land use distributions, regional demographics and transportation networks in an explicitly time-dependent fashion. Intended to form the initial elements of an alternative to the conventional four-step transportation planning process, the prototype model incorporates an activity-based travel behavior model in a micro-simulation approach utilizing a geographic information system platform to manipulate survey, demographic, land use and network databases. An aggregate classification using travel diaries produces representative activity patterns that are implicitly specified in terms of temporal information, activity purpose and sequencing. The classification also provides probability distributions of activity dimensions such as purpose and duration. Additional households are sampled and, based on demographic, land use and...

Can Land Use Policy Really Affect Travel Behavior? A Study of the Link between Non-Work Travel and Land Use Characteristics

Fri, 11 Apr 2003 00:00:00 +0000

Planners are increasingly viewing land use policies as a way to manage transportation demand. Yet the evidence on the link between land use and travel behavior is inconclusive. This paper uses travel diary data for Southern California residents to examine the demand for non-work travel. Both non-work automobile trips and non-work miles travelled by car are modelled as a function of individual sociodemographic variables and land use characteristics near the person's place of residence. The land use variables are rarely statistically significant, and diagnostic tests suggest that land use (and thus residential location choice) is endogeneous to non-work travel. The implications are twofold. The link between land use and non-work travel is weak at best, at least for the sample studied here, and future research should treat residential location and thus nearby land use characteristics as endogeneous in models of travel behavior.

The Potential for Integrating GIS in Activity-Based Forecasting Models

Fri, 11 Apr 2003 00:00:00 +0000

An increased interest in the development and implementation of activity-based modeling approaches has been evident in the ISTEA era given federal mandates to improve current modeling practice. Several activity-based alternatives to conventional regional forecasting are presented. Each of these approaches integrates household activities, land use distributions, regional demographics and transportation networks in a framework that explicitly recognizes the complexity of travel behavior in terms of temporal and spatial constraints, household interactions, transport accessibility and its inherent activity-derived basis. A brief evaluation of the temporal stability of the proposed basic unit of analysis, the household's set of individual activity patterns, leads to a summary of a pattern-based generation model and the initial development of an activity-based microsimulation to replace the demand components of the conventional process.

A Model of Activity Participation and Travel Interactions Between Household Heads

Fri, 11 Apr 2003 00:00:00 +0000

A structural model is used to explain activity interactions between heads of households and, in doing so, to explain household demand for travel. The model attempts to capture links between activity participation and associated derived travel, links between activities performed by male and female heads, links between types of travel, and time-budget feedbacks from travel to activity participation. Data for pairs of opposite gender heads of households are from the 1994 Portland Activity and Travel Survey. The results suggest that a feedback mechanism should be introduced in trip generation models to reflect the effect of activity frequency and duration on the level of associated travel.

Land Use, Urban Design, and Non-Work Travel: Reproducing for Portland, Oregon, Empirical Tests from other Urban Areas

Thu, 10 Apr 2003 00:00:00 +0000

This paper replicates the research on non-work automobile trip generation and land use conducted by Boarnet & Crane (1999) and Boarnet & Sarmiento (1998) for the Portland, Oregon, region. Additionally, new variables examining New Urbanist arguments are incorporated. The results suggest that any links between land use and non-work trip behavior act primarily by influencing trip costs, in terms of distances traveled and speeds achieved, rather than directly influencing the number of trips made. This analysis is consistent with Boarnet and Crane and Boarnet and Sarmiento, suggesting that this model is not sensitive to errors that might arise due to the unique characteristics of the urban area under review.

Why Do People Drive to Shop? Future Travel and Telecommunications Tradeoffs

Thu, 10 Apr 2003 00:00:00 +0000

In this study, we look at the relationship between shopping and travel trips, especially by car, and ask whether the travel trip has intrinsic value and/or costs for shoppers. We first describe recent trends in shopping travel, based on recent travel statistics. We then seek, through the transportation and marketing literatures, different approaches to the question of why people travel to stores. This leads us to pose specific hypotheses about shopping-related trips which we then test using activity-based demand modeling. Our results suggest that the behaviors associated with the adoption of electronic home shopping are complex and that it is naive to view home shopping as just another channel. Home shopping will not evolve independently of other changes in work, daily routines and leisure time use.

Incorporating Yellow-Page Databases in GIS-Based Transportation Models

Thu, 10 Apr 2003 00:00:00 +0000

A systematic approach is developed to transform data in the existing yellow-page databases to a point-based GIS database on activity supply. Such a database is needed for an activity-based travel forecasting system and for disaggregate accessibility analysis. First, the linkage between activity types and business types is established. According to this lookup relationship, businesses and services associated with certain activity types can be selected. These records are then geocoded by address-matching in a GIS and the locations supplying these activities are pinned down. Technical issues such as the difficulty in linking businesses to activities, long term projection and address-matching are discussed and potential solutions are proposed. Finally, issues that need to be addressed when attempting to develop an activity-based forecasting system are examined from the perspective of activity supply.

Accessibility and Auto Use in a Motorized Metropolis

Thu, 10 Apr 2003 00:00:00 +0000

This study uses data from the South Coast metropolitan area in Southern California to examine the effects of automobile and transit accessibility on vehicle holding, vehicle type choice and vehicle use. Household-based models are developed for the total number of vehicles available to the household, the number of vehicles per household member and per driver in the household, the choice of vehicle type for the most recently acquired vehicle and its use in terms of annual mileage. In each model, indicators of accessibility by auto and that by transit are introduced along with residential density and other indicators of residence area, and household attributes. The objective is to use statistical analysis of survey data to assess whether transit accessibility affects auto ownership, vehicle type choice or use in an automobile-dominated area.

Does Neighborhood Design Influence Travel? A Behavioral Analysis of Travel Diary and GIS Data

Thu, 10 Apr 2003 00:00:00 +0000

Can urban design improve the environment? If communities could be designed to reduce automobile use, yes. But can urban design influence travel? Surprisingly, perhaps, the effects of any specific neighborhood feature on travel behavior at the margin are all but unknown. The policy significance of this issue is reflected in the swelling popularity of the "new urbanism" and other planning strategies that use land use tools to mitigate the environmental impacts of metropolitan development. In addition to asserting that development patterns and densities affect how far, how often and by what means people travel, urban designers frequently argue that the legibility and shape of the local street pattern play a key role. "Connected" residential blocks are thus associated with less driving by comparison with the circuitous routes of the modern suburban cul-de-sac -- chiefly by reducing trip lengths and facilitating pedestrian and transit access. Remarkably, there is little empirical...

A Simulation Framework and Environment for Activity Based Transportation Modeling

Thu, 10 Apr 2003 00:00:00 +0000

This paper presents an event-based simulation framework designed specifically for applying activity-based transportation models to a variety of problems. General concepts of activity-based travel modeling are discussed followed by a specification of abstract concepts common to most activity modeling approaches. A simulation framework is developed and implemented in two examples to demonstrate the feasibility of the concepts presented.

Application of Space-Time Prisms for the Measurement of Accessibility

Thu, 10 Apr 2003 00:00:00 +0000

The space-time prisms envisioned by Hagerstrand enclose the locations a person can reach by taking into account various time constraints. This concept has occasionally been used to measure accessibility, but was limited by data availability and computing power. Taking advantages of technological advances, a new procedure utilizing a geographic information system (GIS) is developed to locate facilities within space-time prisms. Data from Portland, Oregon, are applied to demonstrate how the proposed procedure can be used to measure accessibility to health care facilities. The potential of the procedure for measuring accessibility from the activity-based perspective is discussed.

Development of a Microscopic Activity-Based Framework for Analyzing the Potential Impacts of Transportation Control Measures on Vehicle Emissions

Thu, 10 Apr 2003 00:00:00 +0000

The 1990 Clean Air Act Amendments (CAAA) and the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) have defined a set of transportation control measures to counter the rise in vehicle emissions and energy consumption due to increased travel. The value of these TCM strategies is unknown as there are limited data available to measure the travel effects of individual TCM strategies and the models are inadequate for forecasting changes in travel behavior that result from these strategies. The work described in this paper begins to provide an operational methodology to overcome these difficulties so that the impacts of the policy mandates of both CAAA and ISTEA can be assessed. This research demonstrates the benefits in vehicle emissions reduction based on optimal scheduling and linking of the activities performed by the individuals in a household. The potential of transportation policy options to alleviate vehicle emissions is determined in a comprehensive activity-based...

iCHASE: An Internet Computerized Household Activity Scheduling Elicitor Survey

Thu, 10 Apr 2003 00:00:00 +0000

The primary goal of activity-based models is a fundamental examination of the behavioral process that results in revealed travel behavior. To reveal this process, a new computer program, iCHASE, has been developed to collect data for a study of the determinants of travel and activity behavior in households. These data are inherently dynamic, since respondents record planned activity schedules and then update these schedules on a daily basis, fully defined in time and space. The resultant data will facilitate the identification of fundamental inter-relationships among a comprehensive range of revealed travel and activity participation variables, leading toward the identification of the critical variables, relationships and rules that govern that behavior. It is believed that an Internet-based travel survey, particularly one as rich in resultant content as iCHASE, will significantly reduce data collection costs, improve data quality and quantity and allow for continuous data...

An Activity-Based Travel Pattern Generation Model

Wed, 9 Apr 2003 00:00:00 +0000

Activity-based approaches are perhaps the most promising alternative to the current travel forecasting methodology. This paper presents a pattern generation model that can serve as a link between activity and trip-based methodologies. The model uses a clustering approach to identify groups of similar activity-travel behavior and relates them to household socioeconomic attributes. Minimally, the pattern generation model is offered as a possible replacement to the standard trip generation models. Moreover, it can serve as the core component of a proposed activity-based microsimulation model that constructs complete origin-destination tables using a wholly activity-based approach. The technique proposed clearly recognizes the complex nature of activity-travel behavior in terms of spatial and temporal constraints, household interactions and the derived nature of such behavior. An application of the model is outlined using data from the 1994 Portland activity-travel survey.

Measuring the Impact of Efficient Household Travel Decisions on Potential Travel Time Savings and Accessibility Gains

Wed, 9 Apr 2003 00:00:00 +0000

Using the conceptual framework of time-space geography, this paper incorporates both spatio-temporal constraints and household interaction effects into a meaningful measure of the potential of a household to interact with the built environment. Within this context, personal accessibility is described as a measure of the potential ability of individuals within a household not only to reach activity opportunities but to do so with sufficient time available for participation in those activities, subject to the spatio-temporal constraints imposed by their daily obligations and transportation supply environment. The incorporation of activity-based concepts in the measurement of accessibility as a product of travel time savings not only explicitly acknowledges a temporal dimension in assessing the potential for spatial interaction but also expands the applicability of accessibility consideration to such real-world policy options as the promotion of ride-sharing and trip chaining...

TravelBehavior.com: Activity Approaches to Modeling the Effects of Information Technology on Personal Travel

Wed, 9 Apr 2003 00:00:00 +0000

Accessibility can no longer be measured only in terms of travel time, distance or generalized travel cost. Information technology gives individuals "virtual accessibility" to a rapidly growing range of activities. Each person who shops at home on the Internet, or uses a handheld Internet device to gather information about the transportation system before embarking on a trip might only change his or her overall pattern of travel behavior just a little. But there are millions of people worldwide who will be doing similar things on any given day. The small effects scale up to be significant. Travel behavior researchers need to develop models of activity and travel behavior that are capable of capturing the present and future impacts of telecommunications on activity and travel behavior. This paper explores how we might do that.

New Highways, Urban Development and Induced Travel

Wed, 9 Apr 2003 00:00:00 +0000

We examine the link between highways and urban development by employing both hedonic analysis and multiple sales techniques to study the impact on house prices of the construction of toll roads in Orange County, California. Urban economic theory predicts that if highways improve accessibility, that accessibility premium will be reflected in higher land prices. Our empirical analyses of house sales prices provide strong evidence that the toll roads (the Foothill Transportation Corridor, in particular) created an accessibility premium: homebuyers are willing to pay for the increased access that the new roads provided. Such willingness to pay influences both development patterns and, potentially, induced traffic. The results are consistent with the idea that induced travel is caused, in part, by changes in urban development patterns that are linked to increases in highway capacity.

The Four Step Model

Wed, 9 Apr 2003 00:00:00 +0000

The history of travel demand modeling has been dominated by the four step model. The application of this modeling approach is near universal as in large measure are its criticisms. While the approach has been moderately successful in the aggregate it has failed to perform in most relevant policy tests on both the demand and supply sides. This paper begins with an overview of the four step model (4SM) in the broader context of transportation systems analysis. This discussion is followed by problem and study area definitions, model applications and data requirements. Finally, the most commonly used models in the four step process are illustrated through a sample application. I argue that the widespread use of the 4SM is not due to its analytical superiority but simply because it is the only approach available given current institutional requirements and financial limitations.

A Microsimulation of Daily Activity Patterns

Wed, 9 Apr 2003 00:00:00 +0000

This paper documents the prototype development, application and validation of a pattern synthesis model based on activity-travel pattern classifications. The technique proposed is a microsimulation approach to construct daily activity patterns for individuals established on empirical distributions of representative activity patterns and distributions of additional travel characteristics contained by every pattern. The method clearly recognizes the complex, stochastic nature of activity-travel behavior in terms of activity generation, spatial choice and scheduling components. A successful application of the model is outlined using data from the 1994 Portland Activity Travel Survey.

The Activity-Based Approach

Wed, 9 Apr 2003 00:00:00 +0000

The activity-based approach to travel behavior analysis emerged in the 1970s in reaction to changes in the transportation policy environment. The approach is a richer, more holistic framework in which travel is analyzed as daily or multi-day patterns of behavior related to and derived from differences in lifestyles and activity participation among the population (Jones et al, 1990). It explicitly recognizes and addresses the inability of more conventional trip-based models to reflect underlying behavior. This paper begins with a summary and critique of the conventional trip-based approach. Then, it provides an overview of activity-based approaches and reviews representative examples that can be used to enhance understanding of travel behavior and/or improve forecasting and policy analysis. It concludes with an assessment of the future of both trip-based and activity-based approaches.

Experimenting with a Computerized Self-Administrative Survey: Evaluating a Pilot Study

Wed, 9 Apr 2003 00:00:00 +0000

The process of activity scheduling is crucial to the understanding of travel behavior changes. A new computer program, REACT!,has been developed to collect household activity scheduling data for this purpose. The program is implemented as a stand-alone program with Internet connectivity for remote data transmission. It also contains a GIS for location identification and a special feature that traces the decisions in the scheduling process. A pilot study was conducted in Irvine, California, to evaluate the program performance. Preliminary analysis validated the program's capability of guiding participants to complete data entry tasks on their own, thus achieving the objective of reducing the cost and human resource associated with such a computerized survey. Other positive results regarding objectives of reducing instrumental biases and expanding program capabilities were also obtained. Areas for improvement were also identified in the pilot. Based on the finding, REACT!...

A Bridge between Travel Demand Modeling and Activity-Based Travel Analysis

Wed, 9 Apr 2003 00:00:00 +0000

The focus of this paper is on the demonstration that some rather well-known network-based formulations in operations research that have heretofore largely gone unnoticed in activity-based travel research offer a potentially powerful technique for advancing the general development of the activity-based modeling approach. These formulations can provide an analytical framework that unifies the complex interactions among the resource allocation decisions made by households in conducting their daily affairs outside the home while preserving the utility-maximizing principles presumed to guide such decisions. A mathematical programming formulation is developed and used to identify the similarities and differences between traditional trip-based modeling methodologies and those pertaining to an activity-based approach. It is demonstrated that the two approaches are directly related.

A Latent Factor Model of Observed Activities

Wed, 9 Apr 2003 00:00:00 +0000

This paper examines the problem of describing an activity in a concise, usable way. An activity is defined by a vector of observed attributes. Including more observed attributes improves the explanatory power and theoretical completeness of any model of activities, but simultaneously leads to a combinatorial explosion when considering questions about choosing between activities or sequences of activities -- questions that arise in simulation applications. This paper first builds a description of individual activities using a vector of observed attributes. Then, latent variable analysis is used to reduce this vector to just two latent variables, which together explain most of the variation in the original variables.

A GPS Enhanced In-Vehicle Extensible Data Collection Unit

Wed, 9 Apr 2003 00:00:00 +0000

The rapid advancement of technology has created the opportunity for applying new, powerful tools to transportation engineering problems, but often the very speed of technological change hinders the adoption of these tools in a research environment. This paper documents the development of an extensible data collection unit (EDCU). The unit combines a standard GPS unit, a cellular data modem, and an embedded processor running the Linux operating system. Some preliminary uses and applications of the EDCU are presented as well. The EDCU satisfies multiple functional requirements, due to the flexibility of its modular components and its full-powered operating system. The EDCU will serve the in-vehicle data collection needs of travel demand modelers and ITS researchers for the forseeable future.

An Activity-Based Microsimulation Model for Generating Synthetic Activity-Travel Patterns: Initial Results

Wed, 9 Apr 2003 00:00:00 +0000

This paper describes the development of SIMAP, an activity-based microsimulation model for travel demand forecasting. The model is part of a larger research effort aimed at the development of innovative transportation planning methodologies that address contemporary legislative and judicial mandates. The model builds upon existing research that demonstrates that travel behavior should be viewed holistically using activity-travel patterns, a time-dependent representation of the activities in which an individual engages. A microsimulation approach integrated with a geographic information system is advanced to synthesize individual 24-hour activity-travel patterns for households that reflect the existing transportation/land use system. By using activity-travel patterns as the basis of the SIMAP, the timing, sequencing and connections between activities are explicitly included in the model. The final product of this research is a prototype modeling system that has the potential...

An Agent-Based Activity Microsimulation Kernel Using a Negotiation Metaphor