Nemzetközi szemle: Május
Betonburkolat javítás legjobb gyakorlata: esettanulmányok sorozata
Concrete Repair Best Practices: A Series of Case Studies
Szerző(k):
M. Darter
Applied Research Associates, Inc. USA
Terjedelem: 119 oldal
Concrete pavement restoration (CPR) techniques have gained greater national significance as DOT agencies attempt to further extend infrastructure service lives prior to required major rehabilitation or reconstruction. Various publications have documented design procedures and materials for CPR techniques, but less has been written about best practices for their construction, based on information from contractor and DOT agency practitioners. This report consolidates best practice case studies for six CPR techniques: cross-stitching, dowel bar retrofit, diamond grinding, full depth repair, partial depth repair and slab stabilization. Technical briefs for each CPR case study have also been written to accompany the main report. They have been separately published.
Utazási idő kijelzés az autópálya felhajtók megközelítő útjain
Travel Time Displays at Freeway Entrance Approaches
Szerző(k):
E. Robinson, N. Lerner, J. Singer, D. Baragan, K. Kulbicki, J. Kline, D. Kellman
Westat, Leidos, Inc. USA
Terjedelem: 106 oldal
The Federal Highway Administration as well as State and local agencies face the challenge of providing real-time travel time information to motorists in a manner that allows them to take full advantage of it. One factor contributing to the limited effects of current systems is that the travel time displays are not optimally located. The purpose of this project was to explore the best means of providing travel time information to drivers as they approach a freeway entrance and evaluate how this influenced route choice and diversion. The project consisted of two experimental tasks. The first task was a laboratory-based experiment in which participants were presented with scenarios and video of arterial travel time (ATT) displays and then were asked to provide ratings and to offer location recommendations. The second task was a field implementation over 11 weeks to investigate behavior, ratings, and use of both freeway and ATT information provided near a freeway entrance approach. Information was provided via a variable message sign and in-vehicle. A main outcome of both studies was a better understanding of optimal ways and preferred locations for presenting freeway and ATT information to commuters. Guidance and recommendations are provided.
Hideg helyszíni újrahasznosításban és teljes mélységű újrafeldolgozásban használatos aszfaltbeton anyagtulajdonságai
Material Properties of Cold In-Place Recycled and Full-Depth Reclamation Asphalt Concrete
Szerző(k):
Charles W. Schwartz, Brian K. Diefenderfer, Benjamin F. Bowers
University of Maryland, Virginia Transportation Research Council USA
Terjedelem: 83 oldal
Highway agencies are placing increasing emphasis on sustainability, recycling, and making maximum use of existing pavement assets in rehabilitation strategies. Such emphasis has led agencies to explore the advantages of producing asphalt mixtures using cold-recycling technology, particularly cold in-place recycling (CIR), cold central-plant recycling (CCPR), and full-depth reclamation (FDR). The objective of this research was to determine relevant properties of CIR, CCPR and FDR materials with emulsified or foamed asphalt recycling/stabilizing agents for input into pavement structural design programs. The research was conducted by the University of Maryland, College Park, Maryland, with support from the Virginia Transportation Research Council, Charlottesville, Virginia. The project developed a small-scale testing procedure that permits the measurement of the dynamic modulus and repeated load permanent deformation characteristics of field-produced and cured asphalt-stabilized, cold-recycled mixtures. These properties were determined for cold-recycled materials sampled from field projects across the United States. Suggested Level 3 modulus inputs were developed by the research team for use in structural design and analysis programs. Finally, structural analyses were conducted with these inputs in Pavement ME Design that demonstrated the sensitivity of the test data to the different stabilizing agents used in the various field projects.
A jó ellensége – a csaknem tökéletes önvezető járműre várakozás költségének becslése
The Enemy of Good – Estimating the Cost of Waiting for Nearly Perfect Automated Vehicles
Szerző(k):
N. Kalra, D.G. Groves
RAND Corporation USA
Terjedelem: 54 oldal
Many are looking to highly automated vehicles (HAVs)—vehicles that drive themselves some or all of the time—to mitigate the public health crisis posed by motor vehicle crashes. But a key question for the transportation industry, policymakers, and the public is how safe HAVs should be before they are allowed on the road for consumer use. From a utilitarian standpoint, it seems sensible that HAVs should be allowed on U.S. roads once they are judged safer than the average human driver so that the number of lives lost to road fatalities can begin to be reduced as soon as possible. Yet, under such a policy, HAVs would still cause many crashes, injuries, and fatalities—albeit fewer than their human counterparts. This may not be acceptable to society, and some argue that the technology should be significantly safer or even nearly perfect before HAVs are allowed on the road. Yet waiting for HAVs that are many times safer than human drivers misses opportunities to save lives. It is the very definition of allowing perfect to be the enemy of good.
Hosszú távú burkolatviselkedési adatok elemzése és értelmezése Új-Zélandon
Analysis and interpretation of New Zealand long-term pavement performance data
Szerző(k):
K.L. Neaylon, R. Davies, L. Harrow, R. Henderson
Opus Research, Opus International Consultants, New Zealand
Terjedelem: 228 oldal
A comprehensive statistical analysis and review of the dataset was undertaken on the March 2015 LTPP database, including application of transformations on the skewed raw data. Following a detailed analysis, it was found that the numerical data available to undertake a statistical analysis to identify factors that need to be present for accelerated condition trending was not sufficiently robust. It is not possible to find useful or significant correlations with this data set as it stands. A manual investigation by a person with extensive experience in road engineering and maintenance was undertaken. This investigated engineering explanations for the sites highlighted by the statistical analysis, which involved interpreting site photographs, notes and construction records. This review was unable to identify any reliable data to show pavements displaying cracking are at a higher risk of failure. It does suggest, however, that the current selection of maintenance treatment type and the quality of maintenance and reconstruction practices may assist in making the level of service worse after maintenance, compared with sterilised sites where maintenance is restricted to emergency repair work only. The maintenance practice of water cutting also needs to be carefully considered, as this may contribute to a more rapid condition deterioration. Recommendations are provided on how the dataset could be restructured to provide additional benefit.
A közúton végzett munkák forgalmi jellemzőkre gyakorolt hatásainak megértése
Understanding the Impacts of Work Zone Activities on Traffic Flow Characteristics
Szerző(k):
P. Edara, N. Bharadwaj, C. Sun, Y. Chang, H. Brown
University of Missouri-Columbia USA
Terjedelem: 100 oldal
What effect does work activity have on traffic conditions in a work zone? This question has still not been answered satisfactorily in practice. Without knowing the true effect a work activity has on traffic, practitioners are forced to make assumptions while scheduling work. This report attempts to answer this question by studying the traffic flow characteristics for various work activities, i.e., traffic speed versus flow curves, capacity reduction factors, and free-flow speed reduction factors. The importance of the speed-flow curves and reduction factors for work zone planning is also stressed in the latest edition of the Highway Capacity Manual (HCM). The HCM recommends capacity and speed reduction factors for work zones yet does not include specific guidance for including the impact of work activities. Three traffic stream models, Gipps, Newell-Franklin, and Van Aerde, were calibrated using field data from St. Louis, Missouri. The Van Aerde model offered the best fit with the field data compared to the other two models. Using the Van Aerde model-generated speed-flow curves, it was found that the capacity for bridge-related activities varied from 1,416 vehicles per hour per lane (vphpl) to 1,656 vphpl and for pavement-related activities from 1,120 vphpl to 1,728 vphpl.
The capacity reduction factor for different work activities was found to be in the range of 0.68 to 0.95, while the free-flow speed reduction factor was found to be in the range of 0.78 to 1.0. The methodology proposed in this report allows the incorporation of work activity effects into traffic impact assessment tools and results in quantitative guidance for work zone planning and design.
A közúti forgalom megfigyelése fejlett módszerekkel stratégiai kutatás alapján
Advancing Highway Traffic Monitoring Through Strategic Research
Szerző(k):
Standing Committee on Highway Traffic Monitoring
Transportation Research Board USA
Terjedelem: 112 oldal
Data acquisition methods through the decades have progressed from manual counts of vehicles and vehicle type to automated systems that gather vehicle data through the Global Positioning System and cellular devices. Along with the vehicle industry’s electronic revolution, we have witnessed an evolution in our ability to collect vast quantities of different types of data. The issue now is how to manage those data and extract from them the required information to meet state and federal reporting requirements and the other myriad of uses of traffic monitoring data in an expeditious manner.
Transportation planners traditionally have dealt with long-range travel needs and goals, and funding constraints with little consideration of short-term operational issues. Transportation agencies, metropolitan planning organizations, and other interested parties increasingly are recognizing the value of coordination and collaboration among all stakeholders and the operators of the nation’s road network. This E-Circular represents a timely capture of the state of the practice and state of the art in highway traffic monitoring, encompassing the known universe of data acquisition, analysis and reporting tools, quality assurance and quality control techniques, and trends in emerging technologies. It will aid traffic management agencies, transportation planners, and designers in understanding how accurate highway traffic data are acquired and used, and will provide the entire transportation community with an excellent explanation of current practices and gaps in knowledge from which to move forward. The document provides guidance to those involved with highway data acquisition, reporting, and its applications, and will assist them in meeting present day and future requirements. Furthermore, each section presents suggested research that is needed to close the gaps in current knowledge and practices.
Forgalmi menedzsment döntéstámogató eszköz fejlesztése gyorsforgalmi utak esemény menedzsment tervének alkalmazásához
Development of a Traffic Management Decision Support Tool for Freeway Incident Traffic Management (FITM) Plan Deployment
Szerző(k):
W. Kim, H. Kim, M. Won, G.L. Chang
University of Maryland USA
Terjedelem: 125 oldal
Traffic incidents have long been recognized as the main contributor to congestion in highway networks. Thus, contending with non-recurrent congestion has been a priority task for most highway agencies over the past decades. Under most incident scenarios, if proper diversion plans can be implemented in time, motorists can circumvent the congested segments and best use the available corridor capacity. To tackle this vital operational issue, transportation professionals have proposed a variety of advanced diversion control and route guidance strategies to optimally balance the volumes between the freeway and the arterial. In such a system, reliably estimated incident duration plays a key role in selection of strategies for mitigating incident-related delays and impacts. This research developed a methodology for estimating the duration of a detected incident with association rules (SCAR) and two supplemental models using the CHART-II incident database. To minimize the incident impacts, this study further developed two supplemental models: a deployment strategy for incident response units, and a decision support tool for assessing the need of implementing detouring operations. With these three models, responsible highway agencies can have reliable information to tackle critical issues, such as: “what is the estimated duration to clear the detected incident? How far will the maximum queue reach? Can the projected delay and congestion during incident management warrant the detour operations?”
Ejtősúlyos behajlás mérési adatok felhasználása a mechanikai-tapasztalati tervezésben és elemzésben. III. kötet: Behajlás mérési, elemzési és értelmezési útmutató
Using Falling Weight Deflectometer Data with Mechanistic-Empirical Design and Analysis, Volume III: Guidelines for Deflection Testing, Analysis, and Interpretation
Szerző(k):
L.M. Pierce, J.E. Bruinsma, K.D. Smith, M.J. Wade, K. Chatti, J.M. Vandenbossche
Applied Pavement Technology Inc. USA
Terjedelem: 126 oldal
The need to accurately characterize the structural condition of existing pavements has increased with the recent development, release, and ongoing implementation of the Mechanistic-Empirical Pavement Design Guide (MEPDG). A number of different material inputs are required in the procedure, and it is important to adequately characterize and define them. The analysis of deflection data collected by the falling weight deflectometer (FWD) provides a quick and reliable way to characterize the properties of the paving layers, as well as to assess the load carrying capacity of existing pavement structures. With the release of the new MEPDG, there is a pressing need to identify and evaluate the way that FWD testing is integrated into the new design procedure. Moreover, as highway agencies continue to implement the MEPDG, they need best practices guidance on how to effectively test existing pavement structures and interpret the results as part of a mechanistic-empirical pavement evaluation and rehabilitation process. This document is part of a three-volume report investigating the use of the FWD as part of mechanistic-empirical pavement design and rehabilitation procedures. This volume provides best practice guidelines for effective testing of existing pavement structures and interpretation of those results as part of a mechanistic-empirical pavement evaluation and rehabilitation process. Included are guidelines for deflection testing, a discussion of the various data input requirements and suggested default values for backcalculation, a summary of backcalculation modeling issues, and information on measures of convergence and verification of backcalculated results. In addition, general background information is provided on mechanistic-empirical pavement design; data and testing recommendations for project evaluation; and flexible, rigid, and composite pavement inputs. This is volume III of a three-volume report. The other volumes in the series are FHWA-HRT-16-009, Volume I: Final Report, and FHWA-HRT-16-010, Volume II: Case Study Reports.
Közlekedési statisztikai zsebkönyv
Pocket Guide to Transportation
Szerző(k):
Bureau of Transportation Statistics
U.S. Department of Transportation USA
Terjedelem: 69 oldal
The BTS Pocket Guide to Transportation is a quick reference guide that provides transportation statistics at your fingertips. It provides key information and highlights major trends on the U.S. transportation system.