Nemzetközi szemle: Szeptember

Aszfalt burkolatok javított tervezési módszerei
Improved Design Procedures for Asphalt Pavements

Szerző(k): Denneman, E., Lee, J., Dias, M., Dr Laszlo Petho

Austroads Australia
a letöltéshez ingyenes regisztráció szükséges

Terjedelem: 123 oldal

This report is the final deliverable of a three year Austroads project to improve the design procedures for asphalt pavements. The object of the work in this final year was to validate the proposed improved procedures for the characterisation of asphalt modulus and asphalt mix fatigue performance. Based on the work, a revised text for Austroads Guide to Pavement Technology Part 2 has been prepared. Changes include the introduction of flexural modulus master curves for the characterisation of the resilient response of asphalt in pavement design. Field and laboratory experiments were conducted to validate recommended changes. The findings support the proposed changes to the design procedures in the Guide.

Sebességcsökkentési megoldások nagy sebességű környezetben
Speed Reduction Treatments for High-speed Environments

Szerző(k): Austroads Australia
a letöltéshez ingyenes regisztráció szükséges

Terjedelem: 64 oldal

This report examines the performance of different types of speed-reducing treatments (or combinations of treatments) in high-speed environments. The project also considered how desired speed can be aligned with a safe, anticipated operating speed with the goal of making high-speed roads more self-explanatory. Treatments reviewed included: treatments to support development of road hierarchies in line with the concept of self-explaining roads; perceptual countermeasures; transverse rumble strips; vehicle activated signs; gateway treatments; route-based curve treatments; wide median centrelines; and sight distance adjustments on intersection approaches. Based on the outcomes of this review, these treatments may merit further consideration for future Austroads research and guidance.

Hosszú vasúti alagutak világtrendjének elemzése

Trend Analysis of Long Tunnels Worldwide
Szerző(k): Pyeon, J.H. Mineta Transportation Institute, USA

Terjedelem: 62 oldal

High-speed rail construction projects have frequently required long tunnels to reduce travel time and distance. The California High-Speed Rail (CHSR) authority is considering a tunnel up to 16 miles long for a direct route from Palmdale to Burbank. With advances in tunneling technology, the many long tunnels in use around the world today hold valuable lessons for CHSR, particularly with respect to minimization of ground disturbance and improved passenger and operator safety. The primary objective of this project is to determine the state of the art for construction and operation of long tunnels used for high-speed rail. With an abundance of long tunnels successfully completed and already in use around the globe, an examination of those projects can provide the State with the benefit of their experience at little cost. The research began with a review of the literature on long tunnels around the world, with a focus on characteristics and the research team constructed a detailed database of information on the projects behind the world’s long tunnels. Based on the data, this report presents data on 67 tunnels longer than 4.5 miles, including 32 high-speed railway tunnels, located in 28 countries around the world. The research team analyzed the data to determine the factors that should be considered in planning long tunnels for HSR projects. Analysis results were documented in a systematic manner to compare with potential tunnels for the Palmdale-to-Burbank segment of the California HSR system. It is hoped that the trends identified from the aggregate data will help inform decisions for the tunnel projects being considered for the Palmdale-to-Burbank segment of California High-Speed Rail.

Multimodális közlekedési fejlesztések gazdasági hatásainak becslése
Estimating the economic impacts of multimodal transportation improvements
Szerző(k): Zhang, L., Schonfeld, P., Kastrouni, E., Shayanfar, E., He, X.
University of Maryland USA

Terjedelem: 59 oldal

Project selection and prioritization is of the utmost importance to federal, state and local agencies, and should be performed cautiously based on the estimated project costs and benefits. Informed resource allocation decisions among project candidates maximize public investment benefits and create economic opportunities that ultimately improve the quality of life. The objective of this research is to quantify the broader economic impacts of different types of transportation infrastructure investment. The research team integrated the Maryland Statewide Transportation Model with the SHRP2 C11 tools and showcased this integration through four (4) case studies. Using the SHRP2 C11 suite of tools (Development of Improved Economic Analysis Tools), the authors estimate the improvement of travel time reliability and the changes in market access in the study area following the new investment, in performance and monetary terms.

Javított felületi réteg vastagság tervezési változatok fejlesztése helyi utakon

Development of Improved Overlay Thickness Design Alternatives for Local Roads

Szerző(k): Tutumluer, E., Sarker P.
Illinois Center for Transportation USA

Terjedelem: 99 oldal

In this research study, 20 pavement sections were selected from six counties in Illinois, with varying structural and traffic characteristics. Falling weight deflectometer (FWD) tests were conducted on these road segments to determine and monitor the structural conditions of both the existing and HMA overlaid pavement sections. Then the corresponding required overlay thicknesses were determined using three different methods—the AASHTO 1993 nondestructive testing (NDT) method, the IDOT modified layer coefficients method, and the Asphalt Institute deflection approach—that are currently used by local agencies including municipalities, counties and townships. Inadequacies of the currently available methods to properly account for the pavement structural conditions were highlighted. Accordingly, a new mechanistic-empirical (M-E) overlay design method was developed to adequately assess the structural conditions of existing pavements and subsequently recommend required thickness values from FWD based critical pavement responses computed and compared with threshold values for the pre-established fatigue and/or rutting damage algorithms. The M-E overlay design method successfully identified structural deficiencies in the original pavement configurations through FWD NDT and subsequently resulted in reliable and cost-effective overlay solutions, as compared with the IDOT modified layer coefficients method.

Missouri állam burkolat megőrzési programja 1. rész, összegző jelentés
MoDOT Pavement Preservation Research Program. Volume I, Summary Report
Szerző(k): Richardson, D.N.
Missouri University of Science and Technology USA

Terjedelem: 51 oldal

The report documents a research project on pavement preservation performed by the Missouri University of Science and Technology (Missouri S&T) and the University of Missouri-Columbia (UMC) on behalf of the Missouri Department of Transportation (MoDOT). The report is in seven separate volumes consisting of a Summary Report followed by six detailed technical reports. To achieve the goal of reducing maintenance costs and improving minor road ratings, MoDOT has embarked upon a plan of formalizing its maintenance/preservation planning. To assist in developing the plan, MoDOT contracted with Missouri S&T and UMC to conduct a research project, entitled “MoDOT Pavement Preservation Research Program.” The product of this research would become a part of MoDOT’s overall Pavement Management System (PMS). The overall objective of the research was to provide a process that would allow MoDOT to do more selective planning, better engineering and more effective maintenance to minimize costs while maintaining adequate safety and performance of Missouri’s pavements. Six Guidance Documents were created which will act as guidelines for MoDOT’s Pavement Specialists and Pavement Engineers. The work was divided into six tasks, each with its own research (Task) team. The focus of the research was on preservation strategies applied to minor routes.

Autóbusz érkezési idők és utas foglaltságok bizonytalanságának becslése
Estimating Uncertainty of Bus Arrival Times and Passenger Occupancies
Szerző(k): Gayah, V.V., Yu, Z., Wood, J.S.
Mineta National Transit Research Consortium, USA

Terjedelem: 81 oldal

Travel time reliability and the availability of seating and boarding space are important indicators of bus service quality and strongly influence users’ satisfaction and attitudes towards bus transit systems. With Automated Vehicle Location (AVL) and Automated Passenger Counter (APC) units becoming common on buses, some agencies have begun to provide real-time bus location and passenger occupancy information as a means to improve perceived transit reliability. Travel time prediction models have also been established based on AVL and APC data. However, existing travel time prediction models fail to provide an indication of the uncertainty associated with these estimates. This can cause a false sense of precision, which can lead to experiences associated with unreliable service. Furthermore, no existing models are available to predict individual bus occupancies at downstream stops to help travelers understand if there will be space available to board. The purpose of this project was to develop modeling frameworks to predict travel times (and associated uncertainties) as well as individual bus passenger occupancies. For travel times, accelerated failure-time survival models were used to predict the entire distribution of travel times expected. The survival models were found to be just as accurate as models developed using traditional linear regression techniques. However, the survival models were found to have smaller variances associated with predictions. For passenger occupancies, linear and count regression models were compared. The linear regression models were found to outperform count regression models, perhaps due to the additive nature of the passenger boarding process. Various modeling frameworks were tested and the best frameworks were identified for predictions at near stops (within five stops downstream) and far stops (further than eight stops). Overall, these results can be integrated into existing real-time transit information systems to improve the quality of information provided to passengers.

Körfogalmak a gyakorlatban. Az USA közutas gyakorlat szintézise
Roundabout Practices. A Synthesis of Highway Practice

Szerző(k): Pochowski, A., Paul,, A., Rodegerdts, L.A.
Kittelson & Associates, Inc. USA

Terjedelem: 92 oldal

In mid-1997, NCHRP Synthesis of Highway Practice 264: Modern Roundabout Practice in the United
States identified 50 roundabouts known to have been constructed since the beginning of the decade. As of 2013, there were an estimated 3,200 roundabouts in use throughout the country. This synthesis documents and summarizes roundabout policies, guidance, and practices in place within state departments of transportation (DOTs) as of 2015. The primary focus of the synthesis is on roundabout selection and design with a secondary focus on performance analysis. Information used in this study was gathered through a literature review and a survey of state DOTs. Personnel from seven states were interviewed to create case examples and more specific information.