published journal article

Mapping wild vascular plant species diversity in urban areas in California using crowdsourcing data by regression kriging: Examining socioeconomic disparities

Science of The Total Environment

Publication Date

December 20, 2023

Author(s)

Mengyi Li, Shahir Masri, Chun-Huo Chiu, Yi Sun, Jun Wu

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Abstract

Biodiversity is crucial for human health, but previous methods of measuring biodiversity require intensive resources and have other limitations. Crowdsourced datasets from citizen scientists offer a cost-effective solution for characterizing biodiversity on a large spatial scale. This study has two aims: 1) to generate fine-resolution plant species diversity maps in California urban areas using crowdsourced data and extrapolation methods; and 2) to examine their associations with sociodemographic factors and identify subpopulations with low biodiversity exposure. We used iNaturalist observations from 2019 to 2022 to calculate species diversity metrics by exploring the sampling completeness in a 5 × 5-km2 grid and then computing species diversity metrics for grid cells with at least 80 % sample completeness (841 out of 4755 grid cells). A generalized additive model with ordinary kriging (GAM OK) provided moderately reliable estimates, with correlations of 0.64–0.66 between observed and extrapolated metrics, relative mean absolute errors of 21 %–23 %, and relative root mean squared errors of 27 %–30 % for grid cells with ≥80 % sample completeness from 10-fold cross-validation. GAM OK was further applied to extrapolate species diversity metrics from saturated grid cells (N = 841) to the remaining grid cells with <80 % sample completeness (N = 3914) and generate diversity maps that cover the grid. Further, generalized linear mixed models were used to examine the associations between species diversity and sociodemographic indicators at census tract level. The wild vascular plant species diversity metrics were inversely associated with neighborhood socioeconomic status (i.e., unemployment, linguistic isolation, educational attainment, and poverty rate). Minority populations (i.e., African American, Asian American, and Hispanic) and children had significantly lower diversity exposure in their neighborhoods. Crowdsourcing data offers a cost-effective solution for characterizing large-scale biodiversity in urban areas.

Suggested Citation

Mengyi Li, Shahir Masri, Chun-Huo Chiu, Yi Sun and Jun Wu (2023) “Mapping wild vascular plant species diversity in urban areas in California using crowdsourcing data by regression kriging: Examining socioeconomic disparities”, Science of The Total Environment, 905, p. 166995. Available at: 10.1016/j.scitotenv.2023.166995.

conference paper

Accurate individual vehicle speeds from single inductive loop signatures

Proceedings of the 88th annual meeting of the transportation research board

Publication Date

January 1, 2009

Author(s)

Andre (Yeow Chern) Tok, Sarah Hernandez, Stephen Ritchie

Abstract

The paper presents a new model for estimating individual vehicle speeds from conventional round single inductive loop sensors equipped with advanced high-speed scanning detector cards. The model presented improves upon existing models with final results of individual vehicle estimated speeds showing average errors of less than 2 mph and 4 mph, respectively, for two independent test datasets. Improvements to individual vehicle speed estimations can help to enhance analysis in traffic operations and planning fields which depend on accurate speed values such as traffic safety, where knowledge of speed variance is critical. The ability to estimate speed from a single loop, as opposed to double loop speed traps, reduces the need to install double loops and can assist in collecting data when information from double loops is not available.

Suggested Citation

Andre Tok, Sarah Vavrik Hernandez and Stephen G. Ritchie (2009) “Accurate individual vehicle speeds from single inductive loop signatures”, in Proceedings of the 88th annual meeting of the transportation research board, p. 22p.

conference paper

A activity-based modeling framework for transportation policy evaluations

Behavioural research for transport policy : proceedings of the 1985 International Conference on Travel Behaviour

Publication Date

April 1, 1985

Author(s)

Will Recker, Michael McNally

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Abstract

Assessment of the impacts of transportation policies on complex travel behaviour necessarily involves consideration of constraints, absent in conventional techniques, yet fundamental to the activity approach. Policies may be generally viewed as those which either relax or tighten constraints, or alternatively, those which expand or reduce the choice set of individual decision-makers. Whereas existing research has focused on the analysis of relevant constraints in activity/travel behaviour, few extensions have been made to examine choice as central to policy assessment, due to both the strength of accepted relationships between constraints and feasible activity patterns, and limited results relative to choice set formation. The starchild model system (Recker et al) generates feasible activity patterns utilising a constrained, combinatoric scheduling algorithm. This pattern set is subsequently subject to alternate techniques of choice set formation, resulting in a calibrated choice model. The impact of a range of policies (e.g., budget restrictions and activity availability, both temporally and spatially) is estimated within the model structure by examining the resultant changes in individual choice sets. The impacts of the introduction and utilisation of new modes of travel (e.g. electric vehicles) could also be estimated. A brief summary of pertinent research related to the model’s development and a brief examination of the data base utilised in the policy application precedes a comprehensive treatment of model estimation results and the ensuing evaluation for a range of policy scenarios.(a) for the covering abstract of the conference see IRRD 290118.

Suggested Citation

W. W. Recker and M .G. McNally (1985) “A activity-based modeling framework for transportation policy evaluations”, in Behavioural research for transport policy : proceedings of the 1985 International Conference on Travel Behaviour. Noordwijk, The Netherlands, pp. 31–52. Available at: https://swov.nl/en/publicatie/activity-based-modeling-framework-transportation-policy-evaluations.

published journal article

Comparing Markov and non-Markov alternatives for cost-effectiveness analysis: Insights from a cervical cancer case

Operations Research for Health Care

Publication Date

June 1, 2019

Author(s)

Cristina del Campo, Jiaru Bai, Robin Keller

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Abstract

Markov model allows medical prognosis to be modeled with health state transitions over time and are particularly useful for decisions regarding diseases where uncertain events and outcomes may occur. To provide sufficient detail for operations researchers to carry out a Markov analysis, we present a detailed example of a Markov model with five health states with monthly transitions with stationary transition probabilities between states to model the cost and effectiveness of two treatments for advanced cervical cancer. A different approach uses survival curves to directly model the fraction of patients in each state at each time period without the Markov property. We use this alternative method to analyze the cervical cancer case and compare the Markov and non-Markov approaches. These models provide useful insights about both the effectiveness of treatments and the associated costs for healthcare decision makers.

Suggested Citation

Cristina del Campo, Jiaru Bai and L. Robin Keller (2019) “Comparing Markov and non-Markov alternatives for cost-effectiveness analysis: Insights from a cervical cancer case”, Operations Research for Health Care, 21, pp. 32–43. Available at: 10.1016/j.orhc.2019.04.001.

research report

Dynamic traffic assignment based on arrival-time-based origin-destination demand

Publication Date

January 1, 2006

Author(s)

R. (Jay) Jayakrishnan, Hyunmyung Kim

Suggested Citation

R Jayakrishnan and Hyunmyung Kim (2006) Dynamic traffic assignment based on arrival-time-based origin-destination demand.

policy brief

What Can Be Done to Speed Up Building Approval for Multifamily Housing in Transit-Accessible Locations?

Publication Date

July 18, 2022

Author(s)

Doug Houston, Eric Biber, Giulia Gualco-Nelson, Jae Hong Kim, Moira O'Neill, Narae Lee, Nicholas Marantz

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Abstract

California’s legislature has attempted to address the state’s housing affordability crisis in recent years by adopting numerous laws encouraging new development in transit-accessible and/or jobs-rich areas, but the evidence concerning the impacts of these laws on housing development remains largely anecdotal. In particular, policymakers lack adequate information concerning: (1) the types of neighborhoods where developers are more likely to build; and (2) the causes of delays in approvals for proposed projects in jobs-rich and transit-accessible areas. In new research, scholars from UC Irvine and UC Berkeley address this problem by drawing on a unique project-level dataset, the Comprehensive Assessment of Land Use Entitlements (CALES), to analyze development projects including five or more residential units that were approved for development from 2014 through 2017 in six cities: Inglewood, Long Beach, Los Angeles, Pasadena, Redondo Beach, and Santa Monica.

Suggested Citation

Douglas Houston, Eric Biber, Giulia Gualco-Nelson, Jae Hong Kim, Moira O'Neill, Narae Lee and Nicholas Marantz (2022) What Can Be Done to Speed Up Building Approval for Multifamily Housing in Transit-Accessible Locations?. Policy Brief. UC ITS. Available at: https://doi.org/10.7922/g2tq5zvp.

conference paper

Indoor localization based on floor plans and power maps: Non-line of sight to virtual line of sight

28th international technical meeting of the satellite division of the institute of navigation, ION GNSS 2015

Publication Date

January 1, 2015

Author(s)

J.J. Khalifeh, Zaher Kassas, S.S. Saab

Suggested Citation

J.J. Khalifeh, Z.M. Kassas and S.S. Saab (2015) “Indoor localization based on floor plans and power maps: Non-line of sight to virtual line of sight”, in 28th international technical meeting of the satellite division of the institute of navigation, ION GNSS 2015, pp. 2291–2300.

policy brief

Estimating emissions using an integrated traffic model

Publication Date

January 1, 2011

Author(s)

Qi-Jian Gan, Jielin Sun, Jielin Sun, Jean-Daniel Saphores

Policy Brief

2011-04

Suggested Citation

Qijian Gan, Jielin Sun and Jean-Daniel Saphores (2011) Estimating emissions using an integrated traffic model. Policy Brief 2011-04. ITS-Irvine: University of California Transportation Center.

working paper

Productivity Comparisons of Four Different Modes of Demand Responsive Service in Orange, California

Publication Date

September 5, 1978

Author(s)

Al Hollinden, Rebecca Blair

Working Paper

UCI-ITS-WP-78-3

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Abstract

The Orange County Transit District (OCTD) has operated a community service transit program in the City of Orange, California since May of 1975. Because of an adverse court ruling and a subsequent successful appeal, this service underwent four modal changes. These four modes provide a unique opportunity for comparison. In order of implementation, they were: a demand-responsive Dial-A-Bus, a three-loop fixed route bus system, a two-loop fixed route bus system, and a demand-responsive Dial-A-Taxi system. Five performance indicators were used for the comparison, and the two demand-responsive systems were found more efficient and effective than the fixed route systems. The Dial-A-Taxi system, during its first three months of operation, compared very favorably to Dial-A-Bus. In addition, the Dial A-Taxi system continues to show monthly improvements on each indicator. There may be limited transferability of the information gained in this study, but the data suggests that Dial-A-Taxi can be very efficient and effective in serving cities or suburban areas with population densities of 5000 or less per square mile.

Suggested Citation

Al Hollinden and Rebecca Blair (1978) Productivity Comparisons of Four Different Modes of Demand Responsive Service in Orange, California. Working Paper UCI-ITS-WP-78-3. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/7bv7q4ns.

working paper

The Effect of Improved Fuel Economy on Vehicle Miles Traveled: Estimating the Rebound Effect Using U.S. State Data, 1966-2001

Publication Date

September 21, 2005

Author(s)

Kenneth Small, Kurt van-Dender

Working Paper

UCI-ITS-WP-05-2

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Abstract

We estimate the rebound effect for motor vehicles, by which improved fuel efficiency causes additional travel, using a panel of US states for 1966-2001. Our model accounts for endogenous changes in fuel efficiency, distinguishes between autocorrelation and lagged effects, includes a measure of the stringency of fuel-economy standards, and interacts the rebound effect with income. At sample averages of variables, our 3SLS estimates of the short- and long-run rebound effect are 4.7% and 22.0%. But they decline substantially with income: with variables at 1997-2001 levels they become 2.6% and 12.1%, considerably smaller than typically assumed for policy analysis.

Suggested Citation

Kenneth A Small and Kurt Van Dender (2005) The Effect of Improved Fuel Economy on Vehicle Miles Traveled: Estimating the Rebound Effect Using U.S. State Data, 1966-2001. Working Paper UCI-ITS-WP-05-2. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/1h6141nj.