conference paper
Metrics for Quantifying Shareability in Transportation Networks: The Maximum Network Flow Overlap Problem
102nd Transportation Research Board Annual Meeting 2023
Publication Date
January 1, 2023
Archives: Research Products
published journal article
How concentrated disadvantage moderates the built environment and crime relationship on street segments in Los Angeles
Criminology & Criminal Justice
Publication Date
November 14, 2022
Author(s)
John R Hipp, Sugie Lee, Dong Hwan Ki, Jae Hong Kim
Abstract
Criminological theories have posited that the built environment impacts where crime occurs; however, measuring the built environment is difficult. Furthermore, it is uncertain whether the built environment differentially impacts crime in high-disadvantage neighborhoods. This study extracts features of the built environment from Google Street View images with a machine learning semantic segmentation strategy to create measures of fences, walls, buildings, and greenspace for over 66,000 street segments in Los Angeles. Results indicate that the presence of more buildings on a segment was associated with higher crime rates and had a particularly strong positive relationship with robbery and motor vehicle theft in low-disadvantage neighborhoods. Notably, fences and walls exhibited different relationships with crime. Walls, which do not allow visibility, were strongly negatively related to crime, particularly for robbery and burglary in high-disadvantage neighborhoods. Fences, which allow visibility, were associated with fewer robberies and larcenies, but more burglaries and aggravated assaults. Fences only exhibited a negative relationship with violent crime when they were located in low-disadvantage neighborhoods. The results highlight the importance of accounting for the built environment and the surrounding level of disadvantage when exploring the micro-location of crime.
Suggested Citation
John R Hipp, Sugie Lee, Dong Hwan Ki and Jae Hong Kim (2022) “How concentrated disadvantage moderates the built environment and crime relationship on street segments in Los Angeles”, Criminology & Criminal Justice, p. 17488958221132764. Available at: 10.1177/17488958221132764. conference paper
Best Frennemies? A Characterization of TNC and Transit Users Based on the 2017 NHTS
100th Transportation Research Board (TRB) Annual Meeting
Publication Date
January 1, 2021
Author(s)
Suggested Citation
Farzana Khatun and Jean-Daniel Saphores (2021) “Best Frennemies? A Characterization of TNC and Transit Users Based on the 2017 NHTS”. 100th Transportation Research Board (TRB) Annual Meeting, Washington, DC. working paper
Prices, capacities and service quality in a congestible Bertrand duopoly
Publication Date
September 1, 2005
Author(s)
Areas of Expertise
Abstract
We study the duopolistic interaction between congestible facilities that supply perfect substitutes. Firms are assumed to make sequential decisions on capacities and prices. Since the outcomes directly affect consumers’ time cost of accessing or using a facility, the capacity sharing rule is endogenous. We study this two-stage game for different firm objectives and compare the duopoly outcomes with those under monopoly and at the social optimum. Our findings include the following. First, for profit maximizing firms both capacity provision and service quality, defined as the inverse of time costs of using the facility, are distorted under duopoly: they are below the socially optimal levels. This contrasts with the monopoly outcome, where pricing and capacity provision are such that the monopolist does provide the socially optimal level of service quality. Second, duopoly prices are lower than monopoly prices, but higher than in the social optimum. Hence, while price competition between duopolists yields benefits for consumer, capacity competition is harmful. Third, price-capacity competition implies that higher capacity costs may lead to higher profits for both facilities. Finally, if firms also care about output, this mainly affects pricing behavior; strategic interaction in capacities are much less affected. If duopolists attach a higher weight to output and a correspondingly lower weight to profits, this leads to a deterioration of the quality of service.
Phd Dissertation
An object-relational approach to visual database
Publication Date
January 1, 1998
Author(s)
Suggested Citation
Taehyung Wang (1998) An object-relational approach to visual database. PhD Dissertation. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/1go3t9q/alma991035093066004701. conference paper
On activity-based network design problems
20TH INTERNATIONAL SYMPOSIUM ON TRANSPORTATION AND TRAFFIC THEORY (ISTTT 2013)
Publication Date
January 1, 2013
Associated Project
Author(s)
Abstract
This paper examines network design where OD demand is not known a priori, but is the subject of responses in household or user itinerary choices to infrastructure improvements. Using simple examples, we show that falsely assuming that household itineraries are not elastic can result in a lack in understanding of certain phenomena; e.g., increasing traffic even without increasing economic activity due to relaxing of space-time prism constraints, or worsening of utility despite infrastructure investments in cases where household objectives may conflict. An activity-based network design problem is proposed using the location routing problem (LRP) as inspiration. The bilevel formulation includes an upper level network design and shortest path problem while the lower level includes a set of disaggregate household itinerary optimization problems, posed as household activity pattern problem (HAPP) (or in the case with location choice, as generalized HAPP) models. As a bilevel problem with an NP-hard lower level problem, there is no algorithm for solving the model exactly. Simple numerical examples show optimality gaps of as much as 5% for a decomposition heuristic algorithm derived from the LRP. A large numerical case study based on Southern California data and setting suggest that even if infrastructure investments do not result in major changes in link investment decisions compared to a conventional model, the results provide much higher resolution temporal OD information to a decision maker. Whereas a conventional model would output the best set of links to invest given an assumed OD matrix, the proposed model can output the same best set of links, the same daily OD matrix, and a detailed temporal distribution of activity participation and travel from which changes in peak period OD patterns can be observed. (C) 2013 The Authors. Published by Elsevier Ltd.
Suggested Citation
Jee Eun Kang, Joseph Y.J. Chow and Will W. Recker (2013) “On activity-based network design problems”, in . Hoogendoorn, SP and Knoop, VL and VanLint, H (ed.) 20TH INTERNATIONAL SYMPOSIUM ON TRANSPORTATION AND TRAFFIC THEORY (ISTTT 2013). ELSEVIER SCIENCE BV (Procedia social and behavioral sciences), pp. 157–185. Available at: 10.1016/j.sbspro.2013.05.011.Related Publications
published journal article |
Nov 2015
Strategic hydrogen refueling station locations with scheduling and routing considerations of individual vehicles
Transportation Science
published journal article |
Sep 2013
The location selection problem for the household activity pattern problem
Transportation Research Part B: Methodological
published journal article |
Dec 2009
An activity-based assessment of the potential impacts of plug-in hybrid electric vehicles on energy and emissions using 1-day travel data
Transportation Research Part D: Transport and Environment
working paper
A Simultaneous Dynamic Travel And Activites Time Allocation Model
Publication Date
September 1, 1991
Associated Project
Author(s)
Leo J. G. van Wissen, Thomas Golob, Henk J. Meurs
Areas of Expertise
Abstract
In this paper a model is developed and estimated empirically of the allocation of time to out-of-home activities and travel. The model has three important characteristics.First, the allocation of time to out of home activities by individuals is the key concept in the research reported here. Since there exist interdependencies among time usages for different activities, the joint distribution of all relevant out of home activity times has to be taken into account. Consequently the model developed is multivariate.Second, travel is a derived demand. The amount of travel is the result of the spatial activity behaviour of the individual. Of course, the exact relation between activity performance and travel demand is highly complex. The spatial dispersion and quality of activity locations and the scheduling of activities by individuals are both important elements that need to be studied in order to predict total travel demand from a given activity pattern. Here a much simpler approach is taken. It is assumed that total travel time expenditure over a certain time period (i.e. one week) for an activity is proportional to the total amount of time engaged in that activity.The third main feature or the model is its longitudinal character. Longitudinal data have a number of advantages over cross-sectional (see e.g. Hensher, 1985; Davies and Pickles, 1985; van Wissen and Meurs, 1989). From a statistical point of view it allows the estimation of model parameters conditional on non-observed stationary characteristics and individual taste variations. From a theoretical point of view longitudinal data are necessary in order to identify and estimate dynamic processes. In this study only the statistical advantages of longitudinal data will be used.This paper is organized as follows. In section two an overview is given of earlier related work on the allocation of time and travel consequences. In section three the model methodology will be presented. Next, in section four, the data will be described briefly. Section five contains the empirical results of the model estimation. These results are evaluated and some conclusions are drawn in section six.
Suggested Citation
Leo J. van Wissen, Thomas F. Golob and Henk J. Meurs (1991) A Simultaneous Dynamic Travel And Activites Time Allocation Model. Working Paper. Institute of Transportation Studies, UC Irvine: University of California Transportation Center. Available at: https://escholarship.org/uc/item/0pq5099j.Related Publications
working paper |
Aug 1990
Using Longitudinal Methods for Analysis of a Short-Term Transportation Demonstration Project
working paper |
May 1990
Simultaneous Equation Systems Involving Binary Choice Variables
working paper |
Sep 1991
Court Intervention, The Consent Decree, and The Century Freeway
working paper |
Jun 1991
Home Environment Consequences of Commute Travel Impedance
conference paper
A new formulation for the traveling salesman problem with separation requirement and cost
Proceedings of the 90th annual meeting of the transportation research board, washington, DC
Publication Date
January 1, 2011
Author(s)
Suggested Citation
X. Wang and A.C. Regan (2011) “A new formulation for the traveling salesman problem with separation requirement and cost”, in Proceedings of the 90th annual meeting of the transportation research board, washington, DC. conference paper
High coverage point-to-point transit: Local vehicle routing problem with genetic algorithms
2011 14th international IEEE conference on intelligent transportation systems (ITSC)
Publication Date
October 1, 2011
Author(s)
Jae Young Jung, R. (Jay) Jayakrishnan, Doohee Nam
Suggested Citation
Jaeyoung Jung, R. Jayakrishnan and Doohee Nam (2011) “High coverage point-to-point transit: Local vehicle routing problem with genetic algorithms”, in 2011 14th international IEEE conference on intelligent transportation systems (ITSC). IEEE. Available at: 10.1109/itsc.2011.6082818. published journal article
Performance Based Funding Allocation guidelines for Transit Operations in Los Angeles County
Transportation Research Record
Publication Date
January 1, 1982
Author(s)
Gordon (Pete) Fielding, Subhash R Mundle, Joe Misner
Abstract
During the last five years, transit performance indicators have been widely used in the transit industry. California and New York have used performance indicators to determine eligibility for funding. In Pennsylvania, transit performance measures have been used to provide incentive payments for superior performance, and in Michigan a detailed analysis of transit operations provides the basis for state managerial assistance. In Los Angeles County, nine transit operators, including Southern California Rapid Transit District, provide fixedroute transit service. Between 1977 and 1980, operating cost per vehicle hour increased from $28.52 to $38.76, a rate higher than the consumer price index for the Los Angeles area. In response to state legislation designed to maximize utilization of public subsidies for transit, the Los Angeles County Transportation Commission undertook the development of performance-based guidelines for allocating transit subsidies. The performance guidelines developed in cooperation with the local transit operators are presented here. In this program, service is classified into local and express categories. Seven indicators were chosen to monitor transit performance on a periodic basis. Three indicators were selected to establish standards to be achieved by all fixed-route service operators in Los Angeles County. Compliance with these standards will determine eligibility for discretionary funds (representing 5 percent of operating assistance) in the future. The methodology for quantifying loss of subsidy funds if an operator falls below the established standards is also described. The performance guidelines merit consideration for two reasons. First, they represent an attempt by a large metropolitan area to control transit costs, and second they initiate performance-based funding allocation rather than funding based on demographic characteristics or operating deficits. Both reasons are substantial advancements in the theory and application of performance-based guidelines to transit-financing issues.