54 research outputs found

    Impacts of Covid-19 mode shift on road traffic

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    This article is driven by the following question: as the communities reopen after the COVID-19 pandemic, will changing transportation mode share lead to worse traffic than before? This question could be critical especially if many people rush to single occupancy vehicles. To this end, we estimate how congestion will increases as the number of cars increase on the road, and identify the most sensitive cites to drop in transit usage. Travel time and mode share data from the American Community Survey of the US Census Bureau, for metro areas across the US. A BPR model is used to relate average travel times to the estimated number of commuters traveling by car. We then evaluate increased vehicle volumes on the road if different portions of transit and car pool users switch to single-occupancy vehicles, and report the resulting travel time from the BPR model. The scenarios predict that cities with large transit ridership are at risk for extreme traffic unless transit systems can resume safe, high throughput operations quickly.Comment: 14 pages, 11 figure

    A class of perturbed Cell-Transmission models to account for traffic variability

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    We introduce a general class of traffic models derived as perturbations of cell-transmission type models. These models use different dynamics in free-flow and in congestion phases. They can be viewed as extensions to cell transmission type models by considering the velocity to be a function not only of the density but also of a second state variable describing perturbations. We present the models in their discretized form under a new formulation similar to the classical supply demand formulation used by the seminal Cell-Transmission Model. We then show their equivalence to hydrodynamic models. We detail the proper- ties of these so-called perturbed cell-transmission models and illustrate their modeling capabilities on a simple benchmark case. It is shown that they en- compass several well-known phenomena not captured by classical models, such as forward moving disturbances occurring inside congestion phases. An imple- mentation method is outlined which enables to extend the implementation of a cell transmission model to a perturbed cell transmission model

    A general phase transition model for vehicular traffic

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    to appear on SIAM J. Appl. Math.International audienceAn extension of the Colombo phase transition model is proposed. The congestion phase is described by a two-dimensional zone defined around an equilibrium flux known as the classical fundamental diagram. General criteria to build such a set-valued fundamental diagram are enumerated, and instantiated on several equilibrium fluxes with different concavity properties. The solution of the Riemann problem in the presence of phase transitions is obtained through the construction of a Riemann solver, which enables the definition of the solution of the Cauchy problem using wavefront tracking. The free-flow phase is described using a Newell-Daganzo fundamental diagram, which allows for a more tractable definition of phase transition compared to the original Colombo phase transition model. The accuracy of the numerical solution obtained by a modified Godunov scheme is assessed on benchmark scenarios for the different flux functions constructed

    A Multi-Level Analysis of the Impacts of Services Provided By the UK Employment Retention and Advancement Demonstration

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    Background: The United Kingdom Employment Retention and Advancement (U.K. ERA) demonstration was the largest and most comprehensive social experiment ever conducted in the United Kingdom. It examined the extent to which a combination of postemployment advisory support and financial incentives could help lone parents on welfare to find sustained employment with prospects for advancement. ERA was experimentally tested across more than 50 public employment service offices and, within each office, individuals were randomly assigned to either a program (or treatment) group (eligible for ERA) or a control group (not eligible). Method: article presents the results of a multilevel nonexperimental analysis that examines the variation in office-level impacts and attempts to understand what services provided in the offices tend to be associated with impacts. Result: The analysis suggests that impacts were greater in offices that emphasized in-work advancement, support while working and financial bonuses for sustained employment, and also in those offices that assigned more caseworkers to ERA participants. Offices that encouraged further education had smaller employment impacts. Conclusion: Plausible results are obtained identifying those particular implementation features that tended to be linked to stronger impacts of ERA. The methodology employed also allows the identification of which services are associated with employment and welfare receipt of control families receiving benefits under the traditional New Deal for Lone Parent program

    Enabling Mixed Autonomy Traffic Control

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    We demonstrate a new capability of automated vehicles: mixed autonomy traffic control. With this new capability, automated vehicles can shape the traffic flows composed of other non-automated vehicles, which has the promise to improve safety, efficiency, and energy outcomes in transportation systems at a societal scale. Investigating mixed autonomy mobile traffic control must be done in situ given that the complex dynamics of other drivers and their response to a team of automated vehicles cannot be effectively modeled. This capability has been blocked because there is no existing scalable and affordable platform for experimental control. This paper introduces an extensible open-source hardware and software platform, enabling a team of 100 vehicles to execute several different vehicular control algorithms as a collaborative fleet, composed of three different makes and models, which drove 22752 miles in a combined 1022 hours, over 5 days in Nashville, TN in November 2022

    Hierarchical Speed Planner for Automated Vehicles: A Framework for Lagrangian Variable Speed Limit in Mixed Autonomy Traffic

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    This paper introduces a novel control framework for Lagrangian variable speed limits in hybrid traffic flow environments utilizing automated vehicles (AVs). The framework was validated using a fleet of 100 connected automated vehicles as part of the largest coordinated open-road test designed to smooth traffic flow. The framework includes two main components: a high-level controller deployed on the server side, named Speed Planner, and low-level controllers called vehicle controllers deployed on the vehicle side. The Speed Planner designs and updates target speeds for the vehicle controllers based on real-time Traffic State Estimation (TSE) [1]. The Speed Planner comprises two modules: a TSE enhancement module and a target speed design module. The TSE enhancement module is designed to minimize the effects of inherent latency in the received traffic information and to improve the spatial and temporal resolution of the input traffic data. The target speed design module generates target speed profiles with the goal of improving traffic flow. The vehicle controllers are designed to track the target speed meanwhile responding to the surrounding situation. The numerical simulation indicates the performance of the proposed method: the bottleneck throughput has increased by 5.01%, and the speed standard deviation has been reduced by a significant 34.36%. We further showcase an operational study with a description of how the controller was implemented on a field-test with 100 AVs and its comprehensive effects on the traffic flow

    2000 Ohio-Grape Wine Short Course

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    Air, water, sun, and fire--the cooper's footprint on the barrel / Henry Work -- Keeping the bugs unhappy; successful barrel sanitation and maintenance / Henry Work -- Recommended methods for cleaning and maintaining oak cooperage / Phil Burton and Henry Work, with Jim Yerkes -- Chip me, stave me, oak me! The romance, dollars and sense of barrel alternatives / Tim DiPlacido -- Oak experiments / Roland Riesen -- Barrel experiment / Nick Ferrante -- Exploring the versatility and potential of vidal / Roland Riesen -- Ferrante: 1999 vineyard planting / Nick Ferrante -- Breeding rootstocks for current and impending viticultural problems / Andrew Walker -- Grape expectations looking toward traditional and non-traditional sponsors to enhance your event / Doniella Winchell -- Assessing grape maturity by taste and by numbers / Thomas Henick-Kling -- Influence of fruit condition on wine quality / James F. Gallander -- Influence of post bottling storage temperature and SO2 on wine quality / T. E. Steiner -- What we do at harvest to help wine quality / Tony Debevc -- Delivering wine quality / Nick Ferrante -- Criteria for selecting rootstocks / Andrew Walker -- A comparison of Pinot noir production in New York and Burgundy / Pascal Durand and Leslie Weston -- A unique approach to harvest labor / Fran Massaro -- New fungicide registrations for grapes in the year 2000 / Michael Ellis -- Studies to determine time of susceptibility of grape berry and rachis tissues to infection by Phomopsis viticola / O. Erincik, L. V. Madden, D. C. Ferree and M. A. Ellis -- Rootstock performance in Ohio / Arnie Esterer -- Growing your own: vinifera grafting experiments (1999) / Ron Barrett -- Developing an effective fungicide spray program for wine grapes in Ohio / Michael Ellis -- Light and fruit set / David C. Ferree, David M. Scurlock and John C. Schmid -- Soil amendments and mulches in tree health management / Harry Hoitink, Matthew Krause and Randy Zondag -- Report of 5th International Symposium on Cool Climate Viticulture and Enology / Roland Riesen -- Control strategies for soil insects in the vineyard / Roger Williams and Dan Fickl

    Precarious lives and resistant possibilities: the labour of people with learning disabilities in times of austerity

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    This paper draws on feminist and queer philosophers? discussions of precarity and employment, too often absent from disability studies, to explore the working lives of people with learning disabilities in England in a time of austerity. Recent policy shifts from welfare to work welcome more disabled people into the job market. The reality is that disabled people remain under-represented in labour statistics and are conspicuously absent in cultures of work. We live in neoliberal-able times where we all find ourselves precarious. But, people with learning disabilities experience high levels of uncertainty in every aspect of their lives, including work, relationships and community living. Our research reveals an important analytical finding: that when people with learning disabilities are supported in imaginative and novel ways they are able to work effectively and cohesively participate in their local communities (even in a time of cuts to welfare). We conclude by acknowledging that we are witnessing a global politics of precarity and austerity. Our urgent task is to redress the unequal spread of precaritization across our society that risks leaving people with learning disabilities experiencing disproportionately perilous lives. One of our key recommendations is that it makes no economic sense (never mind moral sense) to pull funding from organisations that support people with intellectual disabilities to work
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