A közlekedésépítési szakterület mérnöki és tudományos folyóirata. ISSN: 2064-0919
14. szám
8. évfolyam
2020 december
14
Bejegyzés

Nemzetközi szemle: Február

Újabb eredmények a biztonság és a torlódás kapcsolatában városi gyorsforgalmi utakon
Further Development of the Safety and Congestion Relationship for Urban Freeways

Szerző(k):
Ingrid B. Potts, Douglas W. Harwood, Chris A. Fees, Karin M. Bauer, Christopher S. Kinzel,
Transportation Research Board Strategic Highway Research Program 2 USA

Terjedelem34 oldal

SHRP 2 Reliability Project L07 provided (1) general guidance on the range of design elements that could be used by transportation agencies to improve travel time reliability and reduce nonrecurrent congestion on urban freeways and (2) the Analysis Tool for measuring operational and safety effectiveness and calculating a life-cycle benefit–cost value. This value can be used to support decision making about the possible use of individual treatments to address actual nonrecurrent traffic conditions. For the safety-effectiveness analysis, a new relationship between safety and congestion was explored, and a mathematical model was developed to quantify crash frequency at various levels of traffic density. This supplemental report presents the research findings on the effort to further develop and refine the original safety and congestion relationship model using two additional independent freeway data sets. The results of this additional research confirmed the graphical relationship between crash frequency and traffic density developed in the original research. The crash rate on urban freeways varies with traffic density in a U-shaped curve. The lowest crash rates occurred at medium traffic densities, with slightly higher crash rates (single-vehicle-dominant) recorded at lower traffic densities and much higher crash rates recorded at higher traffic densities (multiple-vehicle-dominant). Therefore, if a design treatment is effective in reducing nonrecurrent congestion conditions at higher levels of service, it should also be effective in reducing crashes, resulting in a safety benefit.

 

Szintézis és szakirodalmi áttekintés alaprétegek szerkezeti tényezőjének meghatározásához
Synthesis/Literature Review for Determining Structural Layer Coefficients (SLC) of Bases

Szerző(k):
Dennis R. Hiltunen,
Department of Civil and Coastal Engineering University of Florida USA, Florida Department of Transportation USA

Terjedelem33 oldal

FDOT’s current method of determining a base material structural layer coefficient (SLC) is detailed in the Materials Manual, Chapter 2.1, Structural Layer Coefficients for Flexible Pavement Base Materials. Currently, any new base material not approved under FDOT specifications must undergo (1) laboratory testing, (2) test pit investigation, and (3) a project test section for constructability and roadway performance evaluation to determine a SLC for design purposes. The test section evaluation phase can take up to five years to compare the pavement performance of the new base material with a limerock base control section. In this project, a thorough review of literature has been conducted of current and past practices for the determination of structural layer coefficients (SLC) of pavement base materials. The review organizes the methodologies into three broad categories: (1) methods that determine SLCs via relationships with other material parameters; (2) methods that determine SLCs via estimates of the structural number (SN) of existing and available pavement sections; and (3) methods that establish SLCs via equivalencies with a reference material. Several of the strategies reviewed provide opportunities for estimating SLCs of both traditional and new base course materials in a more accelerated fashion and in considerably less time than the five years often required at present.

 

Mart aszfalt maximális újrafelhasználása – második év eredménye: újrafelhasznált aszfalt keveréktervezés
Maximising the Re-use of Reclaimed Asphalt Pavement – Outcomes of Year Two: RAP Mix Design

Szerző(k):
Jeffrey Lee, Erik Denneman, Young Choi
Austroads Australia

Terjedelem67 oldal

This report presents the findings from the second year of a three year Austroads study which aims to maximise the re-use of reclaimed asphalt pavement (RAP) in new asphalt mixes. A survey was conducted in Australia to identify the important issues that limit the use of RAP in asphalt. A literature review has been conducted to address the issues identified in the survey. Asphalt mixes containing different percentages of RAP were tested in the laboratory to evaluate the impact of RAP on the volumetrics, flexural stiffness, fatigue, permanent deformation and moisture susceptibility of the asphalt mixes. Viscosity was identified as an important indicator to rank the performance of dense graded asphalt mixes containing different percentages of RAP. For the asphalt mixes tested in this study, increasing viscosity of the binder (after the addition of RAP) will generally increase the stiffness, reduce the rut depth and wheel tracking rate, as well as result in a general reduction of fatigue life. A guideline for design of RAP mixes is also presented in this report.

 

Az INRIX főútvonali utazási idő adatainak validálása és kiterjesztése független forrásokkal
Validation and Augmentation of INRIX Arterial Travel Time Data Using Independent Sources

Szerző(k):
Ali Haghani, Xuechi Zhang, Masoud Hamedi
University of Maryland USA
Maryland State Highway Administration USA

Terjedelem50 oldal

Travel time data is a key input to Intelligent Transportation Systems (ITS) applications. Advancement in vehicle tracking and identification technologies and proliferation of location-aware and connected devices has made network wide travel time data available to transportation management agencies. The trend started with data collection on freeways has been quickly extended to arterials. Although freeway travel time data has been validated extensively in recent years, the quality of arterial travel time data is not well known. This project presents a comprehensive validation scheme for arterial travel time data based on GPS probe and Bluetooth generated data as two independent sources. Since travel time on arterials is subject to a higher degree of variation compared to freeways mainly due to presence of signals, a new validation methodology based on coefficient of variation was introduced. Moreover, a Context Dependent (CD) based travel time fusion framework was developed to improve the reliability of travel time information by fusing data from multiple sources. The entire 2012 data on a busy arterial corridor consisting of six segments in Maryland was used to demonstrate the proposed comparison and augmentation model.

 

Teljesítmény menedzsment a gyakorlatban (szakfolyóirat célszám)
Performance Management in Practice

Szerző(k):
Hyun-A Park, Mara Campbell, Daniela Bremmer, Kirk T. Steudle, Mike Hancock, Julie Lorenz, Carlos Braceras, Jeffrey F. Paniati, Frederick G. (Bud) Wright, Gregory Slater, Frances Harrison, Ananth Prasad, Trish Hendren
TR News July-August 2014 Transportation Research Board USA

Terjedelem: 60 oldal

The full PDF version of the TR News July-August 2014 issue assembles a comprehensive how-to on performance management in transportation. Authors explore current thinking, lessons learned, tools and techniques, and issues related to performance management—what works and what does not. Features detail the experience of a CEO in championing performance management; how state DOTs are using performance measures in long-range planning; successful efforts to communicate performance management information; development of organizational support for performance management; underpinnings of performance measurement and decision making with quality information; the interrelationship between transportation asset management and performance management; and more. The July-August 2014 issue of TR News includes the following articles:

  • Performance Management in Practice: Working Together to Improve Results
  • The Benefits of Performance Management: A Chief Executive Officer’s Perspective
  • Integrating Performance Measures into States’ Long-Range Transportation Plans
  • Telling Our Stories Powerfully, One Data Set at a Time
  • Organizational Support for Performance Management
  • Evaluating Transportation System Performance: Mapping Out a National Framework
  • Performance Management for All: Building on the States’ Robust Foundation
  • Partners in Performance: Working Together to Transform the Nation’s Transportation System
  • Transportation Performance Management: Theory and Practice, Challenges, and Strategies for Success
  • Transportation Asset Management and Performance Management: A Symbiotic Relationship
  • Moving from Reactive to Strategic Decision Making: Ten Basic Steps Toward Performance Management

 

Új útburkolat sűrűségének értékelése georadarral
Ground Penetrating Radar Evaluation of New Pavement Density

Szerző(k):
Ken Maser, Adam Carmichael
Infrasense, Inc. USA
Washington State Department of Transportation USA

Terjedelem20 oldal

Kivonat:

The objective of this project was to map pavement surface density variations using dielectric measurements from ground penetrating radar (GPR). The work was carried out as part of an Asphalt Intelligent Compaction demonstration project on SR 539 inLynden, WA. This demonstration was part of a larger WSDOT project entitled, “Lynden-Aldergrove Port of Entry Improvements.” The research found that comparing the GPR dielectrics and core air void data showed no significant correlation. It was speculated this lack of correlation could be due to a density gradient within the 4-inch asphalt depth, and the fact that the GPR equipment only captures the properties of the top 1-1.5 inches. By focusing on the thinnest asphalt sections, the correlation was significantly improved, with an R2 of 0.77.


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