Nemzetközi szemle: Június
Elektromos útrendszerek: a jövő megoldása
Electric Road Systems: a solution for the future
Szerző(k): Bateman, D. Leal, S. Reeves, M. Emre, L. Stark, F. Ognissanto, R. Myers, M. Lamb (TRL Academy, UK)
Terjedelem: 239 oldal
This study has drawn on literature, stakeholder views, cost-benefit analysis and expert opinion in order to review ERS and its potential. There are still many unknowns with regard to these systems, but based on the information currently available the response to the question the study set out to answer “Is ERS a potential solution for the future?” – is in the long term, yes. This study has shown that all three ERS concepts are technically feasible and potentially financially viable and therefore could contribute to decarbonising transport systems. However, in the short term, wide spread implementation of ERS is not likely as there are still many unknowns with regard to its implementation. There are specific safety and maintenance concerns which still need to be addressed, uncertainty around policy and regulations and the business model is not fully developed. ERS may be a viable solution in the shorter term, in certain locations where circumstances prove financially viable i.e. there is likely to be a high uptake such as along bus routes in urban areas or along freight routes between ports and distribution areas.
Elsőbbségi vagy kizárólagos használatú sávok összekapcsolt és önvezető járműveknek
Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles
Szerző(k): Booz Allen Hamilton (WSP, New Jersey Institute of Technology, USA)
Terjedelem: 156 oldal
NCHRP Report 891: Dedicating Lanes for Priority or Exclusive Use by Connected and Automated Vehicles concentrates on identifying and evaluating opportunities, constraints, and guiding principles for implementing dedicated lanes for connected and automated vehicles. It identifies and describes conditions amenable to dedicating lanes for users of these vehicles and the necessary guidance to deploy them in a safe and efficient manner. The analysis, which relied on application of virtual, computer-based models, helps identify potential impacts associated with various conditions affecting lane dedication, market penetration, evolving technology, and changing demand. This report will be of immediate interest to transportation planners responsible for examining opportunities for integrating connected and, eventually, automated vehicles into the highway network.
Hosszú távú burkolatviselkedési vizsgálat: zárójelentés
Long-term Pavement Performance Study: Final Report
Szerző(k): Choummanivong, T. Martin (Austroads, Australia)
Link: https://austroads.com.au/publications/asset-management/ap-t342-19 (letölthető ingyenes regisztrációval)
Terjedelem: 82 oldal
This report summarises the outputs and benefits of the long-term pavement performance (LTPP) study which ran from 1994 to 2018 and was funded by Austroads. The study had three primary objectives: to enhance road asset management strategies by using improved pavement performance models, to compare the performance of a range of Australian pavement sections with United States (US) sections that had been established under the Strategic Highway Research Program Long Term Pavement Performance (SHRP-LTPP) Program, to compare the performance of accelerated loading facility (ALF) test pavements with actual road pavement performance, to investigate the quantitative influence that various maintenance surface treatments had on long-term pavement performance, as determined by the long-term pavement performance maintenance (LTPPM) portion of the study. These objectives were achieved using the LTPP and LTPPM observational data, which was collected from a range of in-service pavement sites specifically set up for the study, in combination with the data obtained from other sources such as ALF and participating road agencies. The ALF experimental data was used to separately investigate the impact of increased axle loads on long-term pavement performance. The data was also used in road deterioration modelling of flexible pavements.
Előzési sávok biztonsága és teljesítménye
Passing Lanes: Safety and Performance
Szerző(k): Espada, C. Stokes, P. Cairney, L. Truong, P. Bennett, M. Tziotis (Austroads, Australia)
Link: https://austroads.com.au/publications/traffic-management/ap-r596-19 (letölthető ingyenes regisztrációval)
Terjedelem: 102 oldal
This report examines the impacts of passing lanes on safety, journey time and user experience and provides guidance to assist in the development of passing lane installation projects. The research found that passing lanes result in safety benefits, including perceived safety by motorists, safer operational conditions, and historical crash reductions. Passing lanes were also found to improve journey times through a small increase in travel speed and a significant reduction in percentage of time spent following a slower vehicle. This project included a literature review, safety analysis, before-and-after analysis of crash records, speed and headway analysis, and overtaking behaviour analysis, journey time analysis, including development of modelling guidance and numerical experiments on the impact of passing lanes on travel speed and per cent time spent following, road user experience survey analysis, including an analysis of perceptions and valuation of level-of-service, a review and re-calibration of the TRAffic on Rural Roads (TRARR) model.
Körforgalmak baleseti előrebecslő modelljeinek és módszereinek fejlesztése
Development of Roundabout Crash Prediction Models and Methods
Szerző(k): Ferguson, J. Bonneson, L. Rodegerdts, N. Foster, B. Persaud, C. Lyon, D. Rhoades (Kittelson & Associates, Inc., Persaud and Lyon, Inc., Write Rhetoric, USA)
Terjedelem: 187 oldal
Safety performance factors (SPFs) and crash modification factors (CMFs) are predictive models that estimate expected crash frequencies. Transportation professionals use these models to identify locations where crash rates are higher than expected, to estimate safety benefits of a proposed project, and to compare the safety benefits of design alternatives. The models help identify and prioritize locations for safety improvements, compare project alternatives by their expected safety benefits, and guide detailed design decisions to optimize safety. Research indicates that roundabouts provide substantial reductions in crashes, especially crashes that result in serious injuries or fatalities. However, the 1st edition of the Highway Safety Manual (HSM) did not include a crash prediction method for roundabouts; therefore, practitioners were not able to quantitatively assess the crash reduction benefits of providing a roundabout at a specific intersection or to investigate the safety effects of complex design decisions at single lane and multilane roundabouts. NCHRP Report 888 provides practitioners with SPFs and CMFs for roundabouts. The models include variables for geometric features and operational characteristics, as well as their expected effects on crash rates for motorized and non-motorized users. The models can be used for planning-level analysis, and, as a project develops and more detailed information is available, for analysis at the intersection level and leg level of an intersection. NCHRP Report 888 is accompanied by online resources, including recommended revisions for the 2nd edition of the HSM, detailed information on the data sources and data pre-processing, and a downloadable slide presentation summarizing the results of the research. These materials are available on the TRB website (trb.org) by searching for “NCHRP Research Report 888”.
Az adat fontos: etika, adatok és nemzetközi kutatási együttműködés a változó világban: egy Workshop előadásai
Data Matters: Ethics, Data, and International Research Collaboration in a Changing World: Proceedings of a Workshop
Szerző(k): Sauer Sloan, J. Alper (National Academies of Sciences, Engineering, and Medicine USA)
Terjedelem: 103 oldal
International research agreements can serve many purposes, but data are always involved in these collaborations. The kinds of data in play within international research agreements varies widely and may range from financial and consumer data, to Earth and space data, to population behavior and health data, to specific project-generated data—this is just a narrow set of examples of research data but illustrates the breadth of possibilities. The uses of these data are various and require accounting for the effects of data access, use, and sharing on many different parties. Cultural, legal, policy, and technical concerns are also important determinants of what can be done in the realms of maintaining privacy, confidentiality, and security, and ethics is a lens through which the issues of data, data sharing, and research agreements can be viewed as well.
Hengerléssel tömörített beton gyors burkolatépítéshez
Roller Compacted Concrete for Rapid Pavement Construction
Szerző(k): K.H. Khayat, N.A. Libre, Z. Wu (Missouri University of Science and Technology USA)
Terjedelem: 103 oldal
The main objective of this research was to develop high-performance Roller Compacted Concrete (RCC) with enhanced solid skeleton to secure greater workability, mechanical properties, and frost durability. The study involved the development of a stepwise mixture design methodology to select aggregate proportioning and particle-size distribution of combined aggregates that can secure high packing density and lead to enhanced performance. RCC mixtures with high packing density of aggregate combination and suitable fresh and hardened properties were used to introduce air-entraining agent (AEA) at different dosages. The effect of binder content, AEA dosage, workability level, adjusted by varying the water-to-solid ratio, mixer type, and compaction energy on RCC performance was evaluated. Test results indicate that the performance of RCC can be improved with the increase in packing density of aggregate skeleton. Higher packing density can enable the reduction of cement content through improved compacted structure of the solid particles. RCC mixtures made with 40% sand, 20% intermediate aggregate, and 40% coarse aggregate led to the highest packing density and best workability and mechanical properties. The binder content, workability level, and compaction technique were shown to affect considerably affect the mechanical properties, whereas the AEA dosage and mixer type had limited effect. The lowest 28-d compressive strength of 5220 psi (36 MPa) is greater than the 3500 – psi (24.1 – MPa) minimum strength for RCC pavement construction. The highest 28-d compressive strength was 8410 psi (58 MPa). The spacing factor of RCC mixtures was consistently below the targeted value of 0.009 in. (230 μm) with an air content lower than 7%. The RCC mixtures exhibited a durability factor greater than 70% after 123 freeze-thaw cycles and failed soon after, reflecting marginal frost durability. The incorporation of AEA significantly improved the salt-scaling resistance. The average mass loss of air-entrained RCC mixtures was lower than 11.8 oz/yd2 (400 g/m2) after 50 freeze-thaw cycles, which is considerably lower than the limit of 29.5 oz/yd2 (1000 g/m2).
Az anyagkutatás határai: évtizedet áttekintő elemzés
Frontiers of Materials Research: A Decadal Survey
Szerző(k): National Materials and Manufacturing Board USA
Terjedelem: 211 oldal
The National Science Foundation (NSF) and the Department of Energy (DOE) requested that the National Academies of Sciences, Engineering, and Medicine perform an in-depth and broad study that will articulate the status and promising future directions of materials research (MR) in the United States in the context of similar efforts worldwide. Included in the statement of task for this assessment is that MR will be considered broadly in terms of material type, forms/structure, property, and phenomenon, as well as the full breadth of approaches to MR (e.g., experiment, theory, computation, modeling and simulation, instrument/technique development, synthesis, characterization, etc.). Assess the progress and achievements in MR over the past decade; Identify the principal changes in the research and development landscape for MR in the United States and internationally over the past decade, and how those changes have impacted MR; Identify MR areas that offer promising investment opportunities and new directions for the period 2020-2030 or have major scientific gaps; Identify fields in MR that may be good candidates for transition to support by other disciplines, applied research and development (R&D) sponsors, or industry; Identify the broad impacts that MR has had and is expected to have on emerging technologies, national needs, and science; Identify challenges that MR may face over the next decade and offer guidance to the materials research community for addressing those challenges; and Evaluate recent trends in investments in MR in the United States relative to similar research that is taking place internationally by using a limited number of case studies of representative areas of MR that either have experienced significant recent growth or are anticipated to see significant near-term growth, and based on those trends, recommend steps that the United States might take either to secure leadership or to enhance collaboration and coordination of such research support, where appropriate, for identified subfields of MR.