Transportation Planning and Modeling

Development of a Path Flow Estimator For Deriving Steady-State and Time-Dependent Origin-Destination Table Trips

Investigators: Will Recker, Anthony Chen, and Michael Zhang

Support: California Department of Transportation, Partners for Advanced Transit and Highways (PATH)

This research proposes to develop a software tool for estimating both steady-state and time- dependent origin-destination CO-D) trip tables using the concept of path flow estimation. The path flow estimator (PFE), originally developed by Bell and Shield (1995), is a one-stage network observer that estimates path flows (hence O-D flows) and path travel times from traffic counts in transportation networks. The core of the PFE is a logit path choice model (i.e., demand), which interacts with link cost functions (i.e., supply) to produce a stochastic equilibrium traffic pattern. The PFE can be implemented for both off-line transportation planning applications and on-line traffic management applications. The PFE is a proven operational model that has been tested in a number of projects in Europe.

 

Development of a Path Flow Estimator For Deriving Steady-State and Time-Dependent Origin-Destination Table Trips – Phase II

Investigator: Will Recker, Anthony Chen, and Michael Zhang

Support: California Department of Transportation, Partners for Advanced Transit and Highways (PATH)

This research is developing a software tool for estimating both steady-state and time-dependent origin-destination (O-D) trip tables using the concept of path flow estimation. The path flow estimator (PFE), originally developed by Bell and Shield (1995), is a one-stage network observer that estimates path flows (hence O-D flows) and path travel times from traffic counts in transportation networks. The core of the PFE is a logit path choice model (i.e., demand) that interacts with link cost functions (i.e., supply) to produce a stochastic equilibrium traffic pattern, The PFE can be implemented for both off-line transportation planning applications and on-line traffic management applications

 

Evaluation of Incorporating Hybrid Vehicle Use of HOV Lanes Institute of Transportation Studies

Investigator: Will Recker

Support: California Department of Transportation, Partners for Advanced Transit and Highways (PATH)

The objective of this study is to evaluate the impacts of allowing use of High Occupancy Vehicle {HOV) lanes by single-occupant gasoline-electric hybrid vehicles. Currently, Assembly Bill 71 allows single-occupant use of HOV lanes by electric and alternative- fuel vehicles (generally CNG) certified by the California Air Resources Board (ARB) as being zero-einission (ZEV), ultra-low-emission (ULEV) and super-ultra-low-emission (SULEV). Allowing hybrid vehicles to use HOV lanes would promote the ownership and usage of hybrid vehicles by providing savings in travel time and reliability. How such benefits affect the hybrid vehicle market are key components in predicting impacts.

This study will employ a microscopic traffic simulation model (using Paramics) incorporating a behavioral model that captures HOV/hybrid lane choice behavior. Demand for hybrid vehicles will be forecast using modified existing models of consumers' automobile choice behavior and vehicle allocation, which in term will feed origin-destination (O-D) matrices. An advanced emission model (based on the Integrated Transportation/Emissions Modeling (ITEM) system) will be integrated into the microscopic simulation model in order to estimate accurate emissions from changing HOV lane operations. Impacts will be measured in terms of the overall levels of vehicle emissions, fuel consumption, and traffic congestion.

 

Evaluation of the California Safe Routes to School Program

Investigators: Marlon Boarnet, Kristen Day

Support: U.S. Department of Transportation and California Department of Transportation/ University of California Transportation Center

We will conduct a pre- and post-evaluation of the California Safe Routes to School (SR2S) construction program. The California SR2S allocates $20 million to local governments for street, sidewalk, and neighborhood and/or traffic design construction projects to improve the safety and feasibility of walking and bicycling to school. This program grew out of the confluence of several trends, including broad national interest in improving the livability and pedestrian friendliness of urban areas. We will select six SR2S sites, and six sites not in the SR2S program as a "control group." We will assess and document changes to SR2S sites that are associated with the construction program, comparing changes to sites not in the program. We will observe pedestrian and bicyclist behavior before and after SR2S construction at each site, and will survey parents before and after SR2S construction at each site to obtain information on attitudes and perceptions of safety .These data will allow an evaluation of the effectiveness of different neighborhood and traffic interventions in improving the safety of children's non-motorized travel near schools, the frequency of walking and bicycling among children, and the interaction between perceived safety, traffic patterns, the physical environment, and walking and bicycling behavior.

 

Evaluation of the California Safe Routes To School Construction Program PHASE II

Investigator: Marlon Boarnet, Craig Anderson and Kristen Day

Support: California Department of Transportation

In this research, we will conduct a pre- and post-evaluation of the California Safe Routes to School (SR2S) construction program. The California SR2S allocates $20 million to local governments for street, sidewalk and neighborhood and/or traffic design construction projects to improve the safety and feasibility of walking and bicycling to school. This program grew out of the confluence of several trends, including broad national interest in improving the livability and pedestrian friendliness of urban areas. We will select twelve SR2S sites, representative of the range of design interventions. We will assess and document changes to the sites, comparing data collected before and after construction. We will observe pedestrian and bicyclist behavior before and after SR2S construction at each site, "and will survey parents before and after SR2S construction at each site to obtain information on attitudes and perceptions .of safety. These data will allow an evaluation of the effectiveness of. different neighborhood and traffic interventions in improving the safety of children’s non-motorized travel near schools, the frequency of walking, and bicycling among children and the interaction between perceived safety, traffic patterns; the physical environment, and walking and bicycling behavior.

 

Expanded Evaluation of the California Safe Routes to School Program, Year 2

Investigators: Marlon Boarnet, Kristen Day, and Craig Anderson

Support: U.S. Department of Transportation and California Department of Transportation/University of California Transportation Center

This research expands an ongoing pre- and post-evaluation of the California Safe Routes to School (SR2S) construction program. The California SR2S allocates $44 million to local governments for infrastructure projects to improve the safety and feasibility of walking and bicycling to school. With support from the University of California Transportation Center and the California Department of Transportation, we are currently evaluating 12 SR2S sites located in Southern California. We seek funding to expand this evaluation to include an additional 6 SR2S sites in Northern California. The expanded evaluation would incorporate several interesting construction projects that are only being pursued in Northern California. The evaluation will use the same research methods as the existing evaluation: ( 1) assessment of changes to SR2S sites that are associated with the construction program; (2) observations of pedestrian, bicyclist, and driver behavior before and after SR2S construction at each site; and (3) surveys of parents before and after SR2S construction at each site to assess attitudes and perceptions of safety. These data will allow an evaluation of the effectiveness of different neighborhood and traffic interventions in improving the safety of children's non-motorized travel near schools, the frequency of walking and bicycling among children, and the interaction between perceived 'i safety, traffic patterns, the physical environment, and walking and bicycling behavior.

 

Forecasting Demand and Values of Travel Time Savings for Freeway HOV, Toll and HOT Facilities: Incorporating Attitudes and Perceptions into Commuter Choice Models

Investigators: David Brownstone and Thomas F. Golob

Support: U.S. Department of Transportation and California Department of Transportation/ University of California Transportation Center

Accurate forecasts of demand for restricted roadway facilities -high occupancy vehicle (HOV) lanes, toll lanes (including congestion pricing), or combined HOV and toll (HOT) lanes on freeways and bridges -are key to the success of such projects. Yet the track record for predictions for such projects throughout the U.S. is dismal; transportation professionals have not been successful in understanding traveler behavior regarding such choice alternatives. The objective of the proposed research is to explore reasons for these failings and to make recommendations regarding priorities for better models. Alternative model specifications documented in the literature will be compared on a common data set. The most effective dataset for this purpose is the panel survey collected in 1997 -1999 for evaluation of the San Diego 1-15 Congestion Pricing Project, combined with recorded toll data and traffic speed data from freeway loop detectors and floating car measurements. The key new feature of this work is the joint modeling of commuters' choices, perceptions of key trip attributes, and attitudes about road pricing. These variables will be related to commuter's sociodemographic information as well as objective traffic network data typically used in demand analysis. This new model is designed to predict both the economic and political feasibility of a project.

 

Handheld Travel Survey Technology to Supplement Vehicle Tracking in a Shared-use Station Car Program

Investigator: Michael G. McNally

Support: U.S. Department of Transportation and California Department of Transportation/University of California Transportation Center

An experimental shared-use station car program, with electric vehicles, is being implemented in association with several public and private sector organizations in Irvine, CA. The goal of this program is to demonstrate the potential of linking shared-use electric vehicles with conventional line-haul public transit services to provide automobile- like accessibility at the ends of the commute trip. The decision to travel with the shared- use vehicles can be understood only through examining the process of how participants schedule activities before and after shared-use vehicles become a travel option. To evaluate system performance, GPS-based in-vehicle tracking technologies are being utilized with web-based travel surveys. It is proposed to supplement this survey approach with a GPS-based handheld device to track travel and activity when not using program vehicles. The handheld device continuously records and stores spatial position, dumping this data via a wireless link to the in-vehicle device (or a designated home or work PC) when completing activities. In conjunction with current program technologies and as a stand-alone technology, the handheld technology will be assessed relative to its efficacy in the acquisition of comprehensive data on daily travel and activities, while minimizing user effort and inconvenience. These devices will also be evaluated as a means of providing remote access to reservation systems and as keyless access to program vehicles.

 

High-Coverage Point to Point Transit: Institutional Feasibility and Demand Study Of Agencies, Users and Operators

Investigator: R. Jayakrishnan and Thomas F. Golob

Support: U.S. Department of Transportation and California Department of Transportation/University of California Transportation Center

This proposal is to conduct the first demand-side surveys on a new design for private-public transit, named HCPPT (High-Coverage Point to Point Transit). The technical and design details of HCPPT are currently under research by the PI in a multi-year sponsored project that is geared towards a pilot field test in the near future. The design is based on Jitney or Shuttle- style operations with a large number of deployed vehicles under a coordinated transit system that uses advanced information supply schemes with fast routing and optimization schemes.

The system design is rather innovative and ensures that no more than one transfer is needed for the travelers, by using transfer hubs as well as reroutable and non-reroutable portions in the vehicles' travel plans. It yields flexibility for demand-side benefits from options such as price incentives for time-bound "passenger-pooling" at the stops without destination constraints, by the users. Ongoing simulation studies have shown that with enough deployed vehicles, the system can be substantially better, even competitive with personal auto travel, compared to the often-unsuccessful traditional DRT systems and the existing fixed route public transit. Furthermore, HCPPT can be incrementally implemented by contracting out services to existing private operators.

The focus in this proposed research is on three aspects – (1) the acceptability of the system from the transit agency side, as well as the private operator agency side, if it is implemented with contracted-out service; (2) the acceptability from the operators, primarily drivers and other transit unions workers; and (3) the detailed demand-side responses towards the concept from potential travelers. The first two aspects will be studied using Delphi techniques. The third will be studied using both stated preference (SP) surveys of potential users and an SP study of revealed behavior in a laboratory simulator environment. The Delphi and SP surveys would yield valuable insights on refining the system design, though no reliable operational demand models are expected. They would also provide insights on developing utility structures for the simulated laboratory behavior study. In addition to making preliminary mode-split demand predictions, the calibrated utility models could then also be initial inputs for the system design and the real-time optimization of the routing operations, which are designed to be based on traveler cost (disutility) models. The supply-side design relies on a "self-learning" system that can also recalibrate these models during actual operations in the future.

 

Six Miles Uphill Both Ways: How Urban Form Impacts a Child’s Trip to School

Investigator: Tracy Elizabeth McMillan

Support: U.S. Department of Transportation and California Department of Transportation/University of California Transportation Center

The primary objective of this dissertation project is to identify the key factors that affect the relationship between urban form and a child's trip to school. In particular, this project will identify the factors that influence parental decision-making about how children travel to school and the relationship of these factors to urban form.

Parent surveys will be used to answer the overall question of how urban form impacts a child's trip to school. Surveys will be distributed to parents of 3rd-6th grade students at 12-18 elementary school sites in California. Traffic observations (vehicular, pedestrian and bicyclist behavior) and measurements of the neighborhood urban design will also be conducted to validate the model on how urban form impacts a child's trip to school.

This dissertation is a unique contribution to the travel behavior literature with its focus on children's travel behavior and specifically the trip to school. Children are an understudied population in travel behavior research, yet their travel needs have a direct impact on household travel patterns. This research will help in the understanding of child and household travel behavior and contribute to the development of better policies and programs to affect school travel behavior and school site planning.

 

Time-Dependent Equilibrium in Urban Commuting: An Exploratory Study

Investigator: R. Jayakrishnan

Support: U.S. Department of Transportation and California Department of Transportation/ University of California Transportation Center

Urban planners have not yet determined whether or not time-dependent equilibria exist in urban networks. Activity-based and microsimulation-based approaches consider transportation networks to be dynamic in nature but do not expect them to exhibit time-dependent travel impedance equilibrium across alternate travel paths and modes. Alternatively, dynamic traffic assignment (DTA) research often assumes the existence of such equilibria. No research has been done on existing urban commute patterns to see if such equilibria exist. This project uses time-dependent speed data from the Los Angeles area to find time-dependent alternate paths for the O-D pairs and to see if they have sufficiently equivalent travel times. This helps us assess the extent to which the assumptions and predispositions of researchers, planners, demand modelers and supply analysts approach real world situations.