Nemzetközi szemle: Március
Zúzalékvázas masztix aszfalt teljesítménye és életciklus költség előnyei
Szerzők: F. Yin, R.C. (West National Center for Asphalt Technology, USA)
Terjedelem: 66 oldal
Stone matrix asphalt (SMA), also called stone mastic asphalt, is a durable and rut-resistant asphalt mixture that relies on stone-on-stone contact to offer strength and a rich mortar binder to provide durability (Hughes 1999). SMA was introduced into the United States in the early 1990s mainly through the efforts of a Technical Working Group established by the Federal Highway Administration. The first SMA project in the United States was constructed in Wisconsin in 1991. Ever since, SMA has gained popularity among highway agencies as a premium asphalt mixture to enhance field performance and extend life expectancy of asphalt pavements and overlays. However, SMA is generally more expensive than the conventional Superpave dense-graded mixture, mainly due to higher asphalt contents, requirements for more durable aggregates, and inclusion of fibers as stabilizers. This study was undertaken to objectively and comprehensively quantify and compare the performance and life-cycle cost benefits of SMA versus those of polymer-modified Superpave dense-graded mixtures used on similar trafficked highways. To accomplish the objective, market analysis was first conducted to determine the current usage of SMA through surveys of state highway agencies (SHAs), state asphalt pavement associations (SAPAs), and knowledgeable individuals in the asphalt pavement industry. Performance analysis was then conducted to compare the long-term field performance of pavement sections with SMA and polymer-modified Superpave dense-graded mixtures. Information gathered from the market analysis and performance analysis was then used as inputs to compare the life-cycle cost between these two mixtures. Finally, a comprehensive review of literature was conducted to summarize the engineering properties and field performance of SMA. Results obtained from this study provide highway agencies with additional guidance regarding the use of SMA as a premium asphalt mixture.
A közúti infrastruktúra vagyon elemekre bontásának minimum szintjei: útmutató
(letölthető ingyenes regisztrációval)
Szerző: G. Rykers (Austroads, Australia)
Terjedelem: 39 oldal
The purpose of this guideline is to assist organisations determine the appropriate minimum level of componentisation for road infrastructure assets. This guideline is designed to facilitate improved integration and alignment of asset management, financial management and financial reporting processes. It is intended that this guideline will drive a more consistent approach to data management, asset recognition and preparation of financial statements. In turn, this will enable more efficient collation of national data sets used to enable equitable reform initiatives.
A közúti infrastruktúra vagyon elemekre bontásának minimum szintjei: kutatási háttér
Szerző: G. Rykers (Austroads, Australia)
Terjedelem: 108 oldal
This report details the background research that underpins the Minimum Levels of Componentisation for Road Infrastructure Assets: Guideline. It provides background information to support organisations with implementation of the Guideline and includes an impact statement. It also explains the methodology used, and details the outcomes of the literature review, stakeholder survey and conformance assessment. The Guideline provides prescriptive minimum levels of componentisation for road infrastructure assets, to enable road authorities to drive improved integration of asset management, financial management and financial reporting. It also provides a benchmark for auditors to drive a more consistent approach to auditing of road agency financial statements. This, in turn, will enable more efficient collation of national data sets used to enable equitable reform initiatives, such as national funding reform. It is applicable to State / Territory Road Agencies and Local Government Authorities.
Összekapcsolt járműves környezet hatásai az intelligens közlekedési rendszerek tervezésére és megvalósítására
Szerzők: D. Krechmer, E. Flanigan, A.T. Rivadeneyra, K. Blizzard, S.Van Hecke, R. Rausch (Cambridge Systematics, Inc. USA)
Terjedelem: 64 oldal
The objective of this document is to assess the impacts of Connected Vehicle (CV) technology on Intelligent Transportation Systems (ITS) planning processes and implementation. This report identifies and analyzes how CV technology may be considered in the ITS planning process and subsequent deployment; and investigates the need for new or enhanced tools, techniques, and data to support ITS planning and operations activities. The report covers ITS functions such as traveler information, freeway management and arterial management. It also includes functions that are currently peripheral to ITS practitioners but may, in the future, become more mainstream, such as Connected and Automated Vehicle (C/AV) technology and deployment and maintenance of roadside units to support security and data management. CV technology is anticipated to have significant impacts on traveler information, crash rates, and available traffic management strategies, and to drive a need for expanded data management and security as well as a need for new operational policies and practices. Agencies may choose to integrate CV into planning functions, engage with broader stakeholder groups, establish mechanisms for continued learning, outreach, and program evolution, and strengthen their communications networks.
Beton burkolatok építése és rehabilitációja forgalom alatt
Szerzők: S. Rao, D. Raghunathan (Applied Research Associates, Inc. USA)
Terjedelem: 95 oldal
With advancements in materials, equipment, placement procedures, and project management techniques, the construction and rehabilitation of concrete pavements can be effectively accomplished under traffic. Many projects have been constructed under varying levels of traffic, ranging from temporary closures to the maintenance of high traffic volumes adjacent to or through the projects. However, the current state of the practice in constructing or rehabilitating concrete pavements under traffic relies primarily on a few high-profile and well-documented projects. This study identified practices from projects representing a wider range of conditions and techniques. Information on existing practices and advancements in concrete pavement construction and rehabilitation was gathered through literature reviews and a survey of state transportation agencies, including that of the District of Columbia and the Illinois Tollway. Furthermore, sixteen case examples were reported to illustrate successful projects conducted under a variety of scenarios.
Szerzők: RSG USA
Terjedelem: 205 oldal
This handbook provides best-practice guidance on recognizing which measurement methodologies apply to which project type (Section 1.0), how to plan a noise measurement program (Section 2.0), descriptions of measurement methodologies and related considerations (Sections 3.0-15.0), terminology (Section 16.0, Appendix A) and measurement instrumentation (Section 17.0, Appendix B) related to highway traffic noise, example report documentation for measurements (Section 18.0, Appendix C), and supporting material for various methodologies (Sections 19.0-21.0, Appendices D-F). Sections 3.0 and 4.0 are directly applicable to the conduct of traffic noise studies required by the Federal Highway Administration (FHWA) noise regulation in 23 CFR 772. Section 22 is a bibliography.
Közlekedéstervezés elérhetőségi indexekkel Hollandiában
Szerző: International Transport Forum
Terjedelem: 28 oldal
Accessibility has been central to physical planning and spatial modelling for more than fifty years. The concept of accessibility, as it accounts for both the pattern of activities and for the links between activities provides a basis for making trade-offs between land-use and transportation policies. This discussion paper overviews the different perspectives and approaches to measuring accessibility, reviews the strengths and weaknesses of different accessibility indicators, and describes the use of accessibility indicators in the Dutch policy and planning practice. The rest of the paper is structured as follows. Section 2 describes different components of accessibility. Section 3 provides a brief review of accessibility measures. Section 4 describes the Dutch practice of applying accessibility indicators in Dutch transport policy and planning, and its limitations and finally, Section 5 presents the conclusions and discussion.
Szintbeni közút-vasút keresztezés forgalmi kockázatát előrebecslő modell
Szerző(k): P. Lu, D. Tolliver, Z. Zheng (Mountain-Plains Consortium USA)
Terjedelem: 37 oldal
The highway-rail crossing accident has been long recognized as a priority safety concern for worldwide rail industries and researchers because traffic crashes at highway-rail crossings are often catastrophic with serious consequences, which include fatalities, injuries, extensive property damage, and delays in both railway and highway traffic. Generalized linear models (GLMs) have been frequently used in highway safety studies to explore the relationship between crash likelihood and contributors and to forecast future highway rail grade crossing accident likelihood because they are believed to be better suited for discrete and non-negative crash frequency data. However, GLMs have several limitations, such as a pre-defined underlying relationship between target variable and predictors and their limitations to fit dynamic non-linear relationships. Non-parametric data mining methods are gaining popularity because they are not required to pre-define the underlying relationship between dependent and independent variables. They also model non-linear relationships among variables with missing data and between contributor variables and predictors. This research seeks to investigate highway rail grade crossing (HRGC) crash predicting models and contributing factors by exploring the application of GLM and data mining models. In summary, data mining models can serve as great alternative modeling tools to perform crash forecasting with relatively accurate forecasting power and strong ability to model non-linear relationships between contributors and crash likelihood. All the models will provide different sets of contributors. However, decision tree models may be hard to apply due to their large tree structure. Since GLM models are parametric, they tend to pick a limited number of explanatory variables; data mining algorithms, also considered as non-parametric algorithms, tend to select more contributor variables. However, the top contributors identified by all the methods agree with each other on traffic exposure variables, such as highway traffic volume, rail traffic volumes, and their travel speed, and also on some crossing characteristics such as warning devices.
Meglévő aszfaltréteg károsodásának jellemzése mechanikai burkolat rehabilitációs tervezéshez
Szerzők: D. Ayyala, H. Lee, H.L. Von Quintus (Applied Research Associates, Inc. USA)
Terjedelem: 200 oldal
Designing rehabilitation strategies for flexible pavements exhibiting various types and levels of distress is a challenge. An important factor related to the design of a rehabilitation strategy is the use of a reliable procedure to evaluate the in-place condition of pavements. A project-level pavement evaluation program should consist of multiple activities to assess structural condition, identify the types of pavement deterioration, and determine the cause of deficiencies that need to be addressed during pavement rehabilitation. One of the critical steps for evaluating the in-place structural condition of existing pavement layers is deflection-basin testing. Deflection basins are used to backcalculate the elastic layer modulus of existing asphalt concrete (AC) layers, which is considered input level 1 for rehabilitation designs in accordance with the Mechanistic-Empirical Pavement Design Guide. Most agencies measure deflection basins as part of their pavement evaluation programs, but few actually use the data to determine the in-place condition of the AC layers. Deflection data are used to establish analysis sections and/or estimate the resilient modulus of the subgrade soils. However, more recently, agencies have started to use the backcalculated elastic layer modulus to determine the amount of in-place fatigue damage in the existing AC layers. This report evaluates the use of deflection-basin data to determine the in-place structural condition of AC layers for rehabilitation design in accordance with the Mechanistic-Empirical Pavement Design Guide – A Manual of Practice. A common use of deflection data is to backcalculate in-place layered elastic modulus values.
Alacsony sebességű multimodális utak tervezési útmutatója
Szerzők: M. Elizer, J. Bockisch, M. Sewell, I. Potts, D. Torbic, J. Gilpin (Gresham, Smith and Partners, Midwest Research Institute, Alta Planning and Design, USA)
Terjedelem: 283 oldal
NCHRP Research Report 880: Design Guide for Low-Speed Multimodal Roadways provides best practice guidance to the designer by referencing a range of acceptable elements, criteria and values for critical dimensions for design of low- to intermediate-speed (45 mph and lower design speed) roadways with a mix of users and (2) assists designers in establishing a balance between operational efficiency, comfort, safety, and convenience for modes on the low- and intermediate-speed roadways. The report also includes detailed design case studies of design processes. The material in this report will be of immediate interest to design practitioners and stakeholders involved in the planning and design of streets and roadways that serve a mix of motorized and non-motorized users on facilities designed for low and intermediate speeds.