Nemzetközi szemle: Május
Helyszíni hideg remix keverékek tényleges aszfalt tartalmának értékelése
Evaluating Effective Asphalt Content in CIR Mixtures
Szerző(k): D.E. Wegman, M. Sabouri
Braun Intertec Corporation, USA
Terjedelem: 29 oldal
In this study, to evaluate the effect of emulsion reduction during the CIR process in the field, three laboratory CIR mix designs were performed using the same RAP material and emulsion at three different mixing temperatures. The mix design results showed that as the mixing temperature increased, the optimum emulsion content decreased significantly. Also, increasing the mixing temperature improved the mixture compaction. Both the dry and retained stabilities were also higher for the high-temperature mixtures. The critical low temperatures of high-temperature mixtures were higher than the room-temperature mixture (indicative of a worse performance) but still lower than -20°C. From the results of this study, it appears that reducing the emulsion content of the CIR mixtures during the heat of the day, does not necessarily deteriorate the mixture properties. This could result in substantial savings for agencies that use this process without sacrificing long-term performance.
Az utazási idő megbízhatóságának fontossága
Does Travel Time Reliability Matter?
Szerző(k): Culotta, V. Fang, F. Habtemichael, D. Pape
Battelle Memorial Institute, MacroSys, LLC, USA
Terjedelem: 64 oldal
This primer provides an overview of the concept of travel time reliability, including why we should care about reliability and how to define and measure it. The primer also describes the cost of an unreliable system to businesses, the traveling public, and local governments and how lack of reliability can impair safety and security. Lastly, practical strategies and actions for creating and maintaining a reliable transportation system are provided along with case study examples of successful State and local efforts. This information is intended to better communicate the concept of reliability and help transportation systems management and operation professionals in designing their own approaches to improving travel time reliability in their area. This primer is based on information from an extensive literature search and review, which located national and international publications addressing the importance of reliable transportation systems, consequences of unreliability, and successful solutions to improve reliability.
Önvezető járművek keresztirányú vándorlásának optimálása a közúti biztonság és a burkolat élettartam javítására
Optimizing the Lateral Wandering of Automated Vehicles to Improve Roadway Safety and Pavement Life
Szerző(k): Zhou, S. Hu, W. Xue, G. Flintsch
Safe-D National UTC, Texas A&M Transportation Institute, USA
Terjedelem: 37 oldal
Because most automated vehicles (AVs) are programmed to follow a set path and maintain a lateral position in the center of the lane, over time significant pavement rutting will occur. This study directly measured AV lateral wandering patterns. It was found that the wandering patterns of both AVs and human-driven vehicles could be modeled with a normal distribution but have significantly different standard deviations, with AV lateral wandering being at least 3 times smaller than the wandering of human-driven vehicles. Modeling with the Texas Mechanistic-Empirical Flexible Pavement Design System (TxME) found that the AVs with smaller lateral wandering would shorten pavement fatigue life by 22 percent and increase pavement rut depth by 30 percent, which leads to a much higher risk of hydroplaning. Researchers also calculated the maximum tolerable rut depths at different hydroplaning speeds. AVs have a much smaller tolerable rut depth than human-driven vehicles due to greater water film thickness in the rutted wheel paths. To reduce the negative impact of AVs on roadway safety and pavement life, this research recommends an optimal AV wandering pattern, a uniform distribution, which results in prolonged pavement life and decreased hydroplaning potential.
Automatizált közösségi közlekedési busz programok értékelési szempontjai
Considerations for Evaluating Automated Transit Bus Programs
Szerző(k): Luna, E. Machek, S. Peirce
John A. Volpe National Transportation Systems Center, USA
Terjedelem: 30 oldal
Given the potential of transit-bus automation, it is critical to evaluate the benefits and challenges from early implementations. A well-designed evaluation can quantify such societal benefits as improving travel time, increasing mobility, and raising transit ridership. This guide aims to assist transit stakeholders with designing and implementing evaluations of automated transit-bus programs. In designing evaluations, transit agencies and other stakeholders should identify program goals and audiences affected by the technology; develop a logic model that maps project inputs, activities, and outcomes; choose an appropriate evaluation design; and collect and analyze data on key performance indicators related to their program goals.
Döntéstámogató keretrendszer és paraméterek dinamikus részidős üzemi sáv használathoz gyorsforgalmi utakon
Decision Support Framework and Parameters for Dynamic Part-time Shoulder Use
Szerző(k): Jenior, B. Schroeder, R. Dowling, J. Geistefeldt, D. Hale
Leidos, Kittelson & Associates Inc., USA
Terjedelem: 140 oldal
Dynamic part-time shoulder use (D-PTSU) opens shoulders for travel beyond fixed (or static) time periods (e.g., weekday peak periods). Dynamically operating the transportation system by matching supply-side strategies in accordance with prevailing conditions and travel demands represents an important advancement in agency adoption of Active Transportation and Demand Management (ATDM) concepts. This report provides agencies with relevant information and best practices for operating D-PTSU on freeways. The report explains how the opening of PTSU can be optimized based on speed and volume conditions observed or modeled on the freeway, and methods for determining specific “decision parameters” for opening the shoulder are presented. The report also assists agencies in determining if D-PTSU is an appropriate strategy where no part-time shoulder use is in place, or where static part-time shoulder use is in place.
Vagyonelemek közti többcélú forráselosztás megvalósításának esettanulmányai
Case Studies in Implementing Cross-Asset, Multi-Objective Resource Allocation
Szerző(k): Spy Pond Partners, LLC, High Street Consulting Group, LLC, Burns & McDonnell, USA
Terjedelem: 115 oldal
NCHRP Research Report 921: Case Studies in Implementing Cross-Asset, Multi-Objective Resource Allocation extends and implements the results of NCHRP Report 806: Cross-Asset Resource Allocation and the Impact on System Performance. Case studies were used to illustrate key issues in implementing a cross-asset resource allocation approach, and the lessons learned were then used to improve the guidance and tools developed in NCHRP Report 806. In addition, a web tool was developed to enable the use of Data Envelopment Analysis (DEA) in the optimization step of the implementation process and to demonstrate use of a web service that transportation agencies can use in their own web applications to automate DEA analysis.
Fenntartható útépítési útmutató
Sustainable Highway Construction Guidebook
Szerző(k): S.T. Muench, G. Migliaccio, J. Kaminsky, M.Z. Ashtiani, A. Mukherjee, C.G. Bhat, J. Anderson
University of Washington, Michigan Technological University, Greenroads International, USA
Terjedelem: 151 oldal
NCHRP Research Report 916 provides practitioner-ready guidance on how to identify and implement practices that advance sustainability during the construction phase of a highway project. The guidance includes information about practices that go beyond regulatory compliance in addressing the environmental, economic, and social dimensions of sustainability. The guidebook is relevant for practitioners in transportation agencies as well as those in the private sector. Those who are responsible for enterprise-level sustainability initiatives in their agency or firm will find information on how to broaden and deepen these initiatives. Practitioners advancing sustainability in highway construction will find information about specific construction practices, as well as how to implement these practices by specifying them in procurement and contracting.
Torlódás kezelési stratégiák társadalmi egyenlőségi hatásai
Social Equity Impacts of Congestion Management Strategies
Szerző(k): Shaheen, A. Stocker, R. Meza
University of California, USA
Terjedelem: 54 oldal
This white paper examines the social equity impacts of various congestion management strategies. The paper includes a comprehensive list of 30 congestion management strategies and a discussion of equity implications related to each strategy. The authors analyze existing literature and incorporate findings from 12 expert interviews from academic, non-governmental organization (NGO), public, and private sector respondents to strengthen results and fill gaps in understanding. The literature review applies the Spatial – Temporal – Economic – Physiological – Social (STEPS) Equity Framework to identify impacts and classify whether social equity barriers are reduced, exacerbated, or both by a particular congestion mitigation measure. The congestion management strategies discussed are grouped into six main categories, including: 1) pricing, 2) parking and curb policies, 3) operational strategies, 4) infrastructure changes, 5) transportation services and strategies, and 6) conventional taxation. The findings show that the social equity impacts of certain congestion management strategies are not well understood, at present, and further empirical research is needed. Congestion mitigation measures have the potential to affect travel costs, commute times, housing, and accessibility in ways that are distinctly positive or negative for different populations. For these reasons, social equity implications of congestion management strategies should be understood and mitigated for in planning and implementation of these strategies.