conference paper

Method for creating a real-time distributed travel history database - Persistent traffic cookies project

Travel survey methods, information technology, and geospatial data

Publication Date

January 1, 2006

Abstract

A novel distributed method for estimating a trip table in real time is described. The system is called “persistent traffic cookies” by analogy with the use of cookies by web servers to keep track of the current state of web browsers navigating a web site. The method uses traffic cookies placed on in-vehicle computers to maintain the state (current trip) of vehicles moving through the system. These cookies are persistent from day to day; taken together, they form a complete travel history for a traveler or vehicle. The method leverages the vehicles to store their own travel data and then physically do carry those data around the network. Advantages include scalability in both storage and computational effort as well as the unique ability to incorporate the travel behavior of individuals into real-time traffic predictions. A small-scale simulation is presented to illustrate the concept and its potential applications.

Suggested Citation
James E. Marca, Craig R. Rindt and R. Jayakrishnan (2006) “Method for creating a real-time distributed travel history database - Persistent traffic cookies project”, in Travel survey methods, information technology, and geospatial data. NATL ACAD SCI, pp. 69–77.

published journal article

Field Operational Test of Integrated Freeway Ramp Metering/Arterial Adaptive Signal Control: Lessons Learned in Irvine, California

Transportation Research Record: Journal of the Transportation Research Board

Publication Date

January 1, 2002

Author(s)

C. Arthur MacCarley, Steve Mattingly, Michael McNally, Daniel Mezger, James Moore

Abstract

A systematic evaluation of the performance and effectiveness of a field operational test (FOT) of an integrated corridor-level adaptive control system was attempted from fall 1994 through spring 1999 in Irvine, California. The FOT was conducted by a consortium consisting of the California Department of Transportation (Caltrans), the city of Irvine, and two private-sector consultants—National Engineering Technologies Corporation and Farradyne Systems, Inc., a division of Parsons Brinckerhoff—with the city of Irvine as the lead agency. The FOT was a cost-share funded by FHWA as part of the Intelligent Vehicle Highway System Field Operational Test Program. The FOT involves an integrated advanced transportation management system, which extends the capabilities of existing traffic management systems in the city of Irvine and in Caltrans District 12. The evaluation originally entailed both a technical performance assessment and a comprehensive institutional analysis. This report of the Irvine FOT does not constitute a technical evaluation because of the failure of any of the planned technologies to be successfully implemented in the field. Because of the extended time frame associated with the project and the significant range of technical and institutional issues associated with the development and eventual failure of the FOT, a summary of project development, institutional barriers, and lessons learned is provided.

Suggested Citation
C. Arthur MacCarley, Stephen P. Mattingly, Michael G. McNally, Daniel Mezger and James Moore (2002) “Field Operational Test of Integrated Freeway Ramp Metering/Arterial Adaptive Signal Control: Lessons Learned in Irvine, California”, Transportation Research Record: Journal of the Transportation Research Board, 1811(1), pp. 76–83. Available at: 10.3141/1811-09.

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..

published journal article

Identification of Postpartum Depression in Electronic Health Records: Validation in a Large Integrated Health Care System

JMIR Medical Informatics

Publication Date

March 1, 2023

Author(s)

Jeff Slezak, David Sacks, Vicki Chiu, Chantal Avila, Nehaa Khadka, Jiu-Chiuan Chen, Jun Wu, Darios Getahun

Abstract

Background: The accuracy of electronic health records (EHRs) for identifying postpartum depression (PPD) is not well studied. Objective: This study aims to evaluate the accuracy of PPD reporting in EHRs and compare the quality of PPD data collected before and after the implementation of the International Classification of Diseases, Tenth Revision (ICD-10) coding in the health care system. Methods: Information on PPD was extracted from a random sample of 400 eligible Kaiser Permanente Southern California patients’ EHRs. Clinical diagnosis codes and pharmacy records were abstracted for two time periods: January 1, 2012, through December 31, 2014 (International Classification of Diseases, Ninth Revision [ICD-9] period), and January 1, 2017, through December 31, 2019 (ICD-10 period). Manual chart reviews of clinical records for PPD were considered the gold standard and were compared with corresponding electronically coded diagnosis and pharmacy records using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Kappa statistic was calculated to measure agreement. Results: Overall agreement between the identification of depression using combined diagnosis codes and pharmacy records with that of medical record review was strong (κ=0.85, sensitivity 98.3%, specificity 83.3%, PPV 93.7%, NPV 95.0%). Using only diagnosis codes resulted in much lower sensitivity (65.4%) and NPV (50.5%) but good specificity (88.6%) and PPV (93.5%). Separately, examining agreement between chart review and electronic coding among diagnosis codes and pharmacy records showed sensitivity, specificity, and NPV higher with prescription use records than with clinical diagnosis coding for PPD, 96.5% versus 72.0%, 96.5% versus 65.0%, and 96.5% versus 65.0%, respectively. There was no notable difference in agreement between ICD-9 (overall κ=0.86) and ICD-10 (overall κ=0.83) coding periods. Conclusions: PPD is not reliably captured in the clinical diagnosis coding of EHRs. The accuracy of PPD identification can be improved by supplementing clinical diagnosis with pharmacy use records. The completeness of PPD data remained unchanged after the implementation of the ICD-10 diagnosis coding.

Suggested Citation
Jeff Slezak, David Sacks, Vicki Chiu, Chantal Avila, Nehaa Khadka, Jiu-Chiuan Chen, Jun Wu and Darios Getahun (2023) “Identification of Postpartum Depression in Electronic Health Records: Validation in a Large Integrated Health Care System”, JMIR Medical Informatics, 11(1), p. e43005. Available at: 10.2196/43005.

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.

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.

published journal article

Navigation with cellular CDMA Signals—Part II: Performance analysis and experimental results

IEEE Transactions on Signal Processing

Publication Date

April 1, 2018
Suggested Citation
Joe Khalife and Zaher M. Kassas (2018) “Navigation with cellular CDMA Signals—Part II: Performance analysis and experimental results”, IEEE Transactions on Signal Processing, 66(8), pp. 2204–2218. Available at: 10.1109/tsp.2018.2799166.