conference paper

Effects of Activity-Travel Chaining Propensity on Peak and Off-Peak Travel: Workers Versus Non-Workers

Proceedings, 104th Annual Meeting of the Transportation Research Board

Publication Date

January 1, 2025

Abstract

Activity-travel chaining involves an interconnected series of activities and associated trips that occur between a pair of anchors or primary activities. By this definition, activity-travel chaining includes both the attributes of activities (e.g., location, duration, activity type, etc.) and trips (e.g., schedule, distance, route, mode, etc.). Prior research suggests that activity-travel chaining propensity can greatly influence travel demand and its temporal distribution. With the motivation to support reliable travel forecasting and inform travel demand management strategies, we investigate the direct and indirect effects of activity-travel chaining propensity for three activity types on peak and off-peak motorized person miles traveled (PMT). To perform the investigation, we employ a structural equation modeling (SEM) framework with five mediator variables (i.e., travel time savings ratio, activity space area, average daily trips, non-motorized travel mode share, and transit share) to capture the indirect effects of trip chain propensity (as well as socio-demographic and land use) on motorized PMT. We also compare workers and non-workers by specifying and estimating separate models for each group. The results indicate that activity-travel chaining propensities increase peak-hour motorized PMT for workers and non-workers. Also, non-workers chain maintenance activities during off-peak hours to avoid conducting or traveling to these activities during peak hours. We also find significant effects of location characteristics and mediator variables on peak-hour motorized PMT that policymakers can leverage when formulating travel demand management strategies.

Suggested Citation
Tanjeeb Ahmed and Michael F. Hyland (2025) “Effects of Activity-Travel Chaining Propensity on Peak and Off-Peak Travel: Workers Versus Non-Workers”, in Proceedings, 104th Annual Meeting of the Transportation Research Board. Washington, D.C..

presentation

Pilot Study: Smart Infrastructure for Automated Driving

policy brief

COVID-19 Vaccination Rates Influenced Bus Ridership Recovery

Abstract

COVID-19 has had lasting effects on transit ridership, with the worst declines seen in high-income, better educated, urban neighborhoods. However, declines among immigrant and/or low-income households was well documented prior to the pandemic, as more gained access to private vehicles. This has created a unique challenge for transit agencies to bring riders back to transit in cases where they may have already switched to traveling by car or consciously chose to make fewer trips. To better understand ridership during the pandemic, we documented the recovery of bus ridership in Los Angeles County and its relationship with COVID-19 vaccinations between April and December 2021, before the Omicron COVID-19 wave. We then developed a statistical model that relates LA Metro bus ridership as a percentage of October 2019 levels with the percent of adults fully vaccinated by ZIP code. We tested whether the relationship between vaccinations and bus ridership varied by two events: first, the full reopening of businesses in California and second, the wave of COVID transmission caused by the subsequentDelta variant.

Suggested Citation
David Brownstone and Henry Bernal (2024) COVID-19 Vaccination Rates Influenced Bus Ridership Recovery. Policy Brief. UC ITS. Available at: https://doi.org/10.7922/g2k935wj.

conference paper

The California ATMS Testbed Research Program: An Overview

Proceedings, IVHS America Annual Conference

Publication Date

January 1, 1995

Author(s)

Suggested Citation
Wilfred W. Recker (1995) “The California ATMS Testbed Research Program: An Overview”, in Proceedings, IVHS America Annual Conference. Washington, D. C..

working paper

A Property Rights Framework for Transit Services

Publication Date

December 1, 1995

Author(s)

Daniel B. Klein, Adrian Moore

Working Paper

UCI-ITS-WP-95-22, UCTC 303

Abstract

The paper shows how variations in systems of property rights explain diverse experiences of urban jitneys and buses. Scheduled bus service entails route specific investments and cultivation of a market. If these investments can be expropriated by interloping jitneys, scheduled service will be dissolved. Property rights in curbspace determine whether scheduled service will be preserved, and whether jitney services will co-exist. We analyze the dynamics of thick and thin transit markets, with and without curb rights. We develop a governance system of curb rights that would let bus operators appropriate their own investments in scheduled service, yet would avoid monopoly by letting jitneys and competing scheduled services operate along the same route. A property rights system dispenses with government ownership, franchise contracting, and regulation.

Suggested Citation
Daniel B. Klein and Adrian T. Moore (1995) A Property Rights Framework for Transit Services. Working Paper UCI-ITS-WP-95-22, UCTC 303. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/36f657t2.

research report

Evaluating the Impacts of Start-Up and Clearance Behaviors in a Signalized Network: A Network Fundamental Diagram Approach

Abstract

Numerical simulations have shown that the network fundamental diagram (NFD) of a signalized network is significantly affected by the green ratio. An analytical approximation of the NFD has been derived from the link transmission model. However, the consistency between these approaches has not been established, and the impacts of other factors are still unrevealed. This research evalutes the impacts of start-up and clearance behaviors in a signalized network from a network fundamental diagram approach. Microscopic simulations based on Newell’s car-following model are used for testing the bounded acceleration (start-up) and aggressiveness (clearance) effects on the shape of the NFD in a signalized ring road. This new approach is shown to be consistent with theoretical results from the link transmission model, when the acceleration is unbounded and vehicles have the most aggressive clearance behaviors. This consistency validates both approaches; but the link transmission model cannot be easily extended to incorporate more realistic start-up or clearance behaviors. With the new approach, this project demonstrates that both bounded acceleration and different aggressiveness lead to distinct network capacities and fundamental diagrams. In particular, they lead to start-up and clearance lost times of several seconds; and these lost times are additive. Therefore, the important role that these behaviors play in the NFD shape is studied to reach a better understanding of how the NFD responds to changes. This will help with designing better start-up and clearance behaviors for connected and autonomous vehicles.

Suggested Citation
Wen-Long Jin and Adrià Morales Fresquet (2019) Evaluating the Impacts of Start-Up and Clearance Behaviors in a Signalized Network: A Network Fundamental Diagram Approach. Final Report. Available at: https://escholarship.org/uc/item/36v9c2ct (Accessed: October 11, 2023).

Phd Dissertation

Zero Emission Shared-Use Autonomous Vehicles: A Deployment Construct and Associated Energy Grid and Environmental Impacts

Abstract

For decades, the leading cause of death for American youth has been the car accident, and the largest source of domestic Greenhouse Gas (GHG) and many Criteria Air Pollutants (CAPs) has been the transportation sector. The advent of the autonomous vehicle in combination with Battery-Electric Vehicles (BEVs) and Fuel-Cell Electric Vehicles (FCEVs) presents an opportunity to transcend both pernicious challenges. In particular, the evolution of safer and more efficient autonomous (i.e., robotic) driving behavior via vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication, increased use of electric vehicles, and greater access to affordable and convenient shared (i.e., pooled) rides portend societal benefits including a significant reduction in energy demand and associated pollution. This dissertation evaluates the impact of Shared Autonomous Electric Vehicles (SAEVs, “Saves”) on the California energy grid, GHG emissions, and CAPs. Vehicle-centric impacts (i.e., efficiency changes due to vehicle design and driving behavior) are measured using a vehicle design tool together with a microscopic traffic simulation model to (1) design prototype SAEVs, and (2) measure their energy efficiency for standard and eco-driving scenarios and an array of performance characteristics (e.g., different electric drivetrains, various communication protocols, etc.). Fleet-centric impacts (i.e., changes to vehicle allocation and usage) are measured using ArcGIS with a Caltrans travel demand model dataset to allocate and size SAEV stations, where SAEVs recharge/refuel and are sent to serve nearby trips in a hypothetical SAEV-deployment construct. The Holistic Energy Grid modelling tool (HiGRID) is used to measure SAEV impacts on the California electric grid and grid GHG and CAPs. The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation Model (GREET) is used to measure corresponding transportation sector GHG and CAP impacts. Vehicle-centric energy impacts from SAEV-enabled eco-driving and platooning averaged net efficiency improvements of approximately 6-18%. Fleet-centric impacts include VMT changes from -11% to +36%, largely depending on ridesharing. Depending on SAEV design and operation, over 375,000 metric tons of annual CO2-equivalent GHG emissions could be reduced by adopting the proposed SAEV-deployment construct in lieu of the projected conventionally-driven vehicle fleet. Corresponding CAP impacts include a net reduction of over 250 metric tons of annual NOx emissions.

Suggested Citation
VAN THOMAS WIFVAT (2019) Zero Emission Shared-Use Autonomous Vehicles: A Deployment Construct and Associated Energy Grid and Environmental Impacts. PhD Dissertation. UC Irvine. Available at: https://escholarship.org/uc/item/5398t15h.

conference paper

Performance of artificial neural networks for incident detection in ITS

TRANSPORTATION CONGRESS: CIVIL ENGINEERS - KEY TO THE WORLD'S INFRASTRUCTURE, PROCEEDINGS OF THE 1995 CONFERENCE, VOLS 1 AND 2

Publication Date

January 1, 1995
Suggested Citation
B Abdulhai and SG Ritchie (1995) “Performance of artificial neural networks for incident detection in ITS”, in . Lall, BK and Jones, DL (ed.) TRANSPORTATION CONGRESS: CIVIL ENGINEERS - KEY TO THE WORLD'S INFRASTRUCTURE, PROCEEDINGS OF THE 1995 CONFERENCE, VOLS 1 AND 2. AMER SOC CIVIL ENGINEERS, pp. 227–238.

research report

Analysis of Activity-travel Patterns and Tour Formation of Transit Users [Research Brief]

Publication Date

April 1, 2021

Abstract

The complexity of travel behavior has evolved as travelers respond to varying activity demands and the changing supply environment, measured by congestion, cost, and emerging technologies. Complexity in travel behavior is often manifested by an increasing tendency to chain several activities within a tour to minimize total travel time and the number of trips, leading travelers to seek more flexible travel modes to complete their complex travel demands.

Suggested Citation
Michael G McNally and Rezwana Rafiq (2021) Analysis of Activity-travel Patterns and Tour Formation of Transit Users [Research Brief]. researchBrief. Available at: https://rosap.ntl.bts.gov/view/dot/67954 (Accessed: October 11, 2023).

published journal article

Bargaining Unit Structure and Organizational Outcomes

Industrial Relations: A Journal of Economy and Society

Publication Date

January 1, 1981
Suggested Citation
James L. Perry and Harold L. Angle (1981) “Bargaining Unit Structure and Organizational Outcomes”, Industrial Relations: A Journal of Economy and Society, 20(1), pp. 47–59. Available at: 10.1111/j.1468-232X.1981.tb00181.x.