Nemzetközi szemle: Február
Habosított meleg aszfalt teljesítménye 4-6 év alatt Virginia államban
Performance of Foamed Warm Mix Asphalt In Virginia Over Four to Six Years
S. D. Diefenderfer
Virginia Transportation Research Council USA
Terjedelem: 32 oldal
The Virginia Department of Transportation (VDOT) began allowing the use of warm mix asphalt (WMA) in 2008 and has become a national leader in the use of WMA technologies. Several WMA technologies were investigated in research projects prior to implementation; however, foamed WMA was not. This study was designed to evaluate the properties and performance of foamed WMA placed during the initial implementation of the technology to determine if the technology has performed as expected. Six mixtures produced using plant foaming technologies and placed between 2008 and 2010 were identified and subjected to field coring and laboratory testing to provide insight as to the performance of foamed WMA mixtures. All coring was performed in 2014, which resulted in pavement ages ranging from 4 to 6 years. Three comparable hot mix asphalt (HMA) mixtures were cored and evaluated to provide average values for comparison. All cores were tested to determine air-void contents and permeability and were subjected to dynamic modulus, repeated load permanent deformation, and Texas overlay testing. In addition, binder was extracted and recovered for performance grading. Test results found similar properties for the WMA and HMA mixtures evaluated. One WMA mixture exhibited high dynamic modulus and binder stiffness, but overlay testing did not indicate any tendency toward premature cracking. All binders were found to have aged between two and three performance grades above that which was specified at construction. WMA binders and one HMA binder aged two grades higher, and the remaining two HMA binders aged three grades, indicating a likely influence on aging from the reduced temperatures at which the early foamed mixtures were typically produced. Overall results indicated that foamed WMA should be expected to perform similarly to HMA. WMA has been fully adopted by VDOT as an alternative to HMA since 2008; however, at the time of implementation of foamed WMA, no studies had been conducted by VDOT to assess the performance of WMA relative to that of HMA. This study validated the assumption that the properties and performance of foamed WMA are similar to those of HMA.
Hálózat alapú jellemzők és számítási módszerek fejlesztése közlekedési hálózatok redundancia értékeléséhez
Development of Network-Based Measures and Computational Methods for Evaluating the Redundancy of Transportation Networks
A. Chen, X. Xu, S. Ryu
Tongji University, Shanghai, China, Seungkyu Ryu, Utah State University, USA
Terjedelem: 33 oldal
Natural and man-made disasters encountered over the past decade have repeatedly emphasized the importance of transportation networks and the need for government agencies and communities to make the transportation system more resilient. In transportation, some researchers have introduced various measures for assessing the resiliency of transportation networks, and redundancy is one of those measures. The objectives of this report are twofold: to develop network-based measures for systematically characterizing the redundancy of transportation networks, and to develop computational methods for evaluating the network-based redundancy measures. Travel alternative diversity and network spare capacity are developed as two quantitative measures to capture the considerations of travelers and planners. The travel alternative diversity dimension evaluates the existence of multiple modes and effective routes available for travelers or the degree of effective connections between an O-D pair. The network spare capacity dimension quantifies the network-wide residual capacity with an explicit consideration of congestion effect and travelers’ route and mode choice behaviors. To implement the two measures in practice, a formal methodology was provided to evaluate the network redundancy. In the context of a general network resiliency evaluation framework, the proposed measures of network redundancy can be considered as a critical component in assessing network resiliency and also designing a transportation network more resilient against disruptions.
Az önvezető és összekapcsolt járművek elterjedését szolgáló stratégiák
Strategies to Advance Automated and Connected Vehicles
J. Zmud, G. Goodin, M. Moran, N. Kalra, E. Thorn
Transportation Research Board USA
Terjedelem: 33 oldal
This briefing document concisely conveys the key findings of NCHRP Research Report 845:
Advancing Automated and Connected Vehicles: Policy and Planning Strategies for State and Local
Transportation Agencies that assesses policy and planning strategies at the state, regional, and local levels that could influence private-sector automated vehicle (AV) and connected vehicle
(CV) choices to positively affect societal goals. The researchers identified and described mismatches between potential societal impacts and factors that influence private-sector decisions on CV and AV technologies. Policy and planning actions that might better align these interests were then identified. Researchers and the project oversight panel identified the promising actions and then conducted in-depth evaluations of the feasibility, applicability, and impacts of 18 strategies.
Az önvezető és összekapcsolt járművek elterjedését szolgáló politikai és tervezési stratégiák az állami és helyi közlekedés irányítói számára
Advancing Automated and Connected Vehicles: Policy and Planning Strategies for State and Local Transportation Agencies
J. Zmud, G. Goodin, M. Moran, N. Kalra, E. Thorn
Transportation Research Board USA
Terjedelem: 160 oldal
Connected vehicle (CV) and automated vehicle (AV) technologies are rapidly entering the fleet and are expected to profoundly change personal, freight, and public transport. The potential benefits to society of these technologies are immense but there are also substantial risks. This report assesses policy and planning strategies at the state, regional, and local levels that could influence private-sector AV and CV choices to positively affect societal goals. The report will be useful to staff responsible for developing plans for reacting to these technologies and is accompanied by a briefing document that may be appropriate for agency decision makers.
Az aszfalt burkolat sűrűségének előírása és mérése a burkolat teljesítmény biztosítására
Specifying and Measuring Asphalt Pavement Density to Ensure Pavement Performance
D. S. Decker
Dale S. Decker, LLC, Colorado, USA
Terjedelem: 66 oldal
The in-place density of asphalt mixtures is the single most important property of the asphalt mixture in the pavement. The relationship between in-place density and the performance of the mixture has been studied for decades. The process of achieving in-place density involves creating the proper mix design, understanding aggregate and asphalt binder properties, understanding paver and roller operations, and adjusting the process to account for environmental conditions. Many details are involved in the process. Significant changes have occurred since the implementation of Superpave for materials and mix design but there is not a standard on how agencies measure and establish specification criteria for in-place pavement density. The objective of this study was to collect specific information on the current state-of-the knowledge of in-place density of asphalt concrete pavements and pavement performance as well as the current practices agencies follow to measure and specify in-place density of asphalt mixtures.
Áruszállító tehergépkocsi konvoj próba Texasban – 2. szintű automatizáltság
Commercial Truck Platooning Demonstration in Texas – Level 2 Automation
B. Kuhn, M. Lukuc, M. Poorsartep, J. Wagner, K. Balke, D. Middleton, P. Songchitruksa, N. Wood, M. Moran
The Texas A&M University System, USA
Terjedelem: 222 oldal
Through this project, the Texas Department of Transportation (TxDOT) funded the creation of a comprehensive truck platooning demonstration in Texas, serving as a proactive effort in assessing innovative operational strategies to position TxDOT as a leader in this research area and the overall transportation systems management and operation using connected vehicle and automated vehicle initiatives. The focus was on the feasibility of deploying truck platoons with two or more vehicles on specific corridors in Texas within 5 to 10 years. The project brought together major partners, including government agencies, national labs, truck manufacturers and equipment suppliers, all of which have committed resources in terms of in-kind matching of equipment, engineering services, and intellectual property.
Szövetségi Útügyi Hivatal kutatási és technológiai értékelés: Nemzeti utazási háztartás-felvételi program zárójelentés
Federal Highway Administration Research and Technology Evaluation: National Household Travel Survey Program Final Report
L. Chajka-Cadin, M. Petrella, C. Timmel, E. Futcher, J. Mittleman
Volpe National Transportation Systems Center, USA
Terjedelem: 102 oldal
This evaluation of the NHTS Program addresses three key questions: What is the breadth and depth of NHTS usage? What impact does the NHTS Program have on policy, project, or regulatory decision making? How responsive is the NHTS Program to its user community? Although it is difficult to trace the specific impacts of the NHTS data, the evaluation found many examples demonstrating that NHTS data inform a range of policy and legislative decisions, both within transportation and in other fields (e.g., health, energy). In some cases, NHTS provides context and understanding for how, when, and why Americans travel, as well as trends in travel. This context helps make the case for particular policy or legislative initiatives. In other cases, NHTS is an important data input to a model or statistical analysis, which is used, in turn, to influence policy or legislation. At the State and local levels, NHTS has its greatest impact in developing, calibrating, or validating travel demand models that are used to inform transportation planning and project selection. The report also identifies challenges and lessons learned regarding survey planning, survey administration, and outreach and offers a set of recommendations to improve program effectiveness.
Főúthálózatok fenntartható üzemeltetése
Sustainable Operation of Arterial Networks
D. Kalathil, A.A. Kurzhanskiy, P. Varaiya
University of California at Berkeley, USA
Terjedelem: 73 oldal
This report describes operational data analysis and modeling of arterial networks with signalized intersections as follows: The setup for data collection, analysis and simulation is presented in Section 2.1. Detailed analysis of collected signal phasing and traffic data is provided in section 2.2. Arterial traffic and platoon modeling is described in Section 2.3. Simulation results of the Rollins Park network is discussed in Section 2.4. Research conducted under this task is an important stepping stone for building a three-level information and control system for urban networks with high-density traffic. In this task researchers focused on elements of link-level information (signal phasing and timing SPaT) estimation and prediction) and vehicle-level control (Adaptive Cruise Control (ACC) and Cooperative Adaptive Cruise Control (CACC)). In SPaT analysis researchers presented several novel algorithms to estimate the residual duration of a signal phase for a semi-actuated intersection. These algorithms predict the times for all future phase transitions, based on previous phase measurements and on the real time information that locates the current time within the current phase. With respect to the vehicle-level control, researchers analyzed sensitivity of intersection throughput to car following models and related parameters. The Improved Intelligent Driver Model (IIDM) was chosen for traffic simulation. Finally, researchers implemented the platoon model in Simulation of Urban MObility (SUMO) and tested it in simulation of scenarios on Rollins Park network.
Gyalogosok kezelése szabályozatlan helyszíneken – eljárások és útmutató kialakítása
Establishing Procedures and Guidelines for Pedestrian Treatments at Uncontrolled Locations
Y. Qi, R.N. Fries, H. Zhou, A. Rab, R. Baireddy
University of Illinois at Urbana–Champaign, USA
Terjedelem: 248 oldal
Pedestrians are the most vulnerable road users. The risks to pedestrians crossing at uncontrolled locations are much higher than at signalized intersections. There has been an increasing trend in pedestrian deaths during the past decade. Specifically, pedestrian fatality as percent of total fatalities indicates an increasing trend in a ten-year period from 2005 to 2014. Several research projects funded by both federal and state transportation agencies have attempted to identify effective strategies for improving pedestrian safety within their jurisdictions. However, very little research was conducted on pedestrian safety at uncontrolled locations in Illinois. The objectives of the project were to identify the best practices of approving pedestrian crossings and pedestrian-crossing treatments at uncontrolled locations and to develop procedures and guidelines to be used by the Illinois Department of Transportation (IDOT) and local agencies. To achieve the research goal, the team conducted a comprehensive literature review of related studies and existing guidelines, a survey and interview of Illinois transportation engineers, statistical analysis of Illinois pedestrian-crash data from 2010 to 2014, and a field review of selected high-crash corridors (HCC) in Illinois. This study identified several common issues associated with the high-pedestrian-crash-prone roads, e.g., speeding, poor lighting, noncompliance with posted signage, inadequate or missing signage, or lack of conspicuity. Several geometric features were also proven to be related to pedestrian crashes; for instance, long crossing distances, insufficient sight distance, and inappropriate placement of bus stops and parking were proved to affect pedestrian safety. In addition, pedestrian-crossing treatments were classified into five categories in the study, and their effectiveness and suitable conditions were assessed and identified. Based on the research findings, a guidebook was compiled with a comprehensive discussion of strategies and treatments to enhance pedestrian safety at uncontrolled locations. The target audiences for this guidebook are transportation professionals, highway designers, traffic engineers, law enforcement officers, and safety specialists who may be involved in efforts to reduce pedestrian crashes at uncontrolled locations.
Legjobb gyakorlat útmutató stabilizált burkolatokhoz
Best practice guide for pavement stabilisation
Opus International Consultants Limited, New Zealand
Terjedelem: 68 oldal
New Zealand pavement engineers, in collaboration with colleagues in South Africa and Australia, are recognised internationally as leaders in the use of stabilisation in highway, road, airport, port and industrial hardstand pavement applications. Stabilisation is used to rectify a deficiency in a soil, aggregate or surfacing material. Stabilised materials contribute to the strength and performance of pavements at all levels: subgrade; subbase; base and surfacing. Applied research into and development of leading edge testing and design knowledge, coupled with significant improvements in the capacity and effectiveness of stabilisation construction plant and work site processes now offer the wider transport industry in New Zealand relatively safe, efficient and sustainable pavement construction, rehabilitation and maintenance options incorporating stabilisation. This research was undertaken to bring together informed, current technical advice from a variety of sources to enable road controlling authorities, consultants and contractors in New Zealand to successfully investigate, design, construct, maintain and operate pavements with stabilised components.