Eric Petersen

Explicit Modeling of Joint Travel by Household Members: Statistical Evidence and Applied Approach

A substantial portion of regional travel is implemented by household members who travel together, primarily to participate in a shared household activity. Joint household travel is not explicitly accounted for in most regional travel models in which the unit of travel (either trip or tour) is considered for each person separately at each modeling stage—generation, mode, destination, and time-of-day choice. In addition, statistical evidence demonstrates that the vast majority of shared-ride travel consists of joint household travel. A modeling approach that distinguishes shared activity-based joint household travel from arranged interhouse-hold carpooling is clearly desirable to support accurate forecasts of shared-ride travel, critical in the evaluation of high-occupancy vehicle lanes or the adoption of toll strategies differentiated by occupancy levels. A range of aspects of joint travel both with empirical evidence and with discussion of modeling issues are addressed. A set of joint travel models is presented that has been estimated with the mid-Ohio regional travel household-interview survey. The model reported is one of the innovative components of the tour-based travel demand modeling system that has been developed for the Mid-Ohio Regional Planning Commission.

Microsimulation in Travel Demand Modeling: Lessons Learned from the New York Best Practice Model

Microsimulation is increasingly assuming a major role in the advancement of demand-modeling practice. At the same time, it is attracting growing attention from the larger transportation-planning community. Four basic advantages of microsimulation versus conventional fractional-probability models are examined. The first is the technical advantage related to computational savings in the calculation and storage of large multidimensional probability arrays. The second is the meaningful advantage gained in the explicit modeling of various decision-making chains and time–space constraints on individual travel that allows for behavioral realism in the demand-modeling procedure. The third relates to the variability of microsimulation outcomes, which can yield full information about the distributions of the travel demand statistics of interest rather than single deterministic estimates or average values. As soon as constraints are introduced into the modeling framework (which often is done at the destination choice stage), competition arises, although generally it has been ignored in standard models. Microsimulation has the potential to handle this competition over work attractions and other travel activities in a meaningful fashion, which is the fourth advantage. These four advantages of microsimulation are discussed in light of the recent development and application of the New York best practice model, a microsimulation demand-modeling system for the New York–New Jersey–Connecticut metropolitan area.

Escorting children to school: Statistical analysis and applied Modeling approach

An important aspect of intrahousehold interactions-joint travel arrangements that arise when adult household members escort children to school-is investigated. Previously published research on intrahousehold interactions have focused mostly on time allocation or episode generation between individual and joint activities and have largely been limited to interactions between household heads. Insights into the less-explored aspect of intrahousehold interactions between adults and children in the household are provided. Children are explicitly considered active agents in the intrahousehold decision making, and the interaction itself takes the form of a joint travel arrangement rather than a shared activity. A statistical analysis indicates the importance of this segment of intrahousehold interactions in the overall system of household activity and travel. A choice model, which is formulated and estimated, relates the probability of various types of ridesharing and escorting to the person, household, and zonal...

IMPACT OF INTRAHOUSEHOLD INTERACTIONS ON INDIVIDUAL DAILY ACTIVITY-TRAVEL PATTERNS

Existing approaches to modeling daily activity-travel patterns (DAPs) are mostly person based. However, intrahousehold interactions have a strong effect on the formation of the daily activity agenda of each household member. An approach is adopted that is based on the sequential modeling of the choices reflected in the DAPs of all household members, in a predetermined order of processing by person type, with explicit linkages between the choices made by different members of the household. The statistical analysis of intrahousehold interactions is described, as well as the application experience with this modeling approach in the framework of the new tour-based regional travel demand model recently developed for the Mid-Ohio Regional Planning Commission. Linkages across different household members that reflect the sharing of the same activities or the making of joint travel proved to be extremely strong statistically.

MODEL FOR ALLOCATION OF MAINTENANCE ACTIVITIES TO HOUSEHOLD MEMBERS

Household maintenance activities and associated tours, even if individually implemented, should be thought of as satisfying the needs of the entire household rather than simply the needs of the person who implements the activity. These activities are characterized by a high degree of substitution between household members who could implement them. This characteristic suggests a modeling structure in which maintenance activities are generated by the entire household and then allocated to the household members for implementation. In this approach, the modeling of allocated activities is executed by a sequence of two linked discrete choice models. The first model relates to the entire household and returns total daily frequency of individual maintenance tours by purpose. The second model relates to the tour level and returns the allocation of each generated tour to a particular household member. Within the general framework of a regional demand modeling system, these models are applied after, and are conditional on, the mandatory and joint tour generation stage. The statistical analysis and model estimation for this implementation of allocated household maintenance activities allow for important insights into the intrahousehold decision-making mechanism and improved travel demand forecasts. Models of this type have been implemented as components of the regional travel demand modeling system recently developed for the Mid-Ohio Regional Planning Commission.

Use of Physical Devices for Calming Traffic Along Major Roads Through Small Rural Communities in Iowa

Many rural communities have developed around highways or major county roads. As a result, the main street through small rural communities is often part of a high-speed rural highway. Highways and county roads are characterized by high speeds outside the city limits and then transition into a reduced-speed section through the rural community. Consequently, drivers passing through the community may enter at high speeds and then maintain those speeds throughout. Traffic calming in small rural communities along major roadways is common in Europe, but the United States does not have experience with applying traffic calming outside of major urban areas. Seven different low-cost traffic treatments were implemented and evaluated in five rural Iowa communities. Two of the treatments physically affected the roadway cross-section. A speed table was placed along the major road (County Highway E-23) in Gilbert, Iowa, and longitudinal channelizers were used to create a center island narrowing along County Highway R-38 in Slater, Iowa. Before and after speed studies were conducted. Speed studies were conducted at 1, 3, 9, and 12 months after installation of the treatments to evaluate their effectiveness over time. Both treatments successfully reduced mean speed, 85th percentile speed, and fraction of vehicles traveling 5, 10, 15, and 20 mph over the posted speed limit; reductions were sustained over time.