Nemzetközi szemle: Április
Nagy sűrűségű aszfaltkeverékek kísérleti és számításos vizsgálata
Experimental and Computational Investigations of High-Density Asphalt Mixtures
Szerző(k): Marasteanu, J.-L. Le, K. Hill, T. Yan, T. Man, M. Turos, M. Barman, U. Maheswar Arepalli, J. Munch
University of Minnesota, USA
Terjedelem: 104 oldal
Compaction of asphalt mixtures represents a critical step in the construction process that significantly affects the performance and durability of asphalt pavements. In this research effort, the compaction process of asphalt mixtures was investigated using a combined experimental and computational approach. The primary goal was to understand the main factors responsible for achieving good density and was triggered by the success of a recently proposed Superpave 5 mix design method. First, a two-scale discrete element method (DEM) model was developed to simulate the compaction process of asphalt mixtures. The computational model was anchored by a fluid dynamics-discrete element model, which is capable of capturing the motion of aggregates in the viscous binder. The model was then calibrated and validated by a series of experiments, which included rheological tests of the binder and a compaction test of the mixture. It was concluded that the compaction process was significantly influenced by the rheological properties of the fine aggregate matrix and by the sphericity of the coarse aggregates. Finally, the mechanical properties of two high-density mixtures were determined and compared with mechanical properties of mixtures used for MnROAD 2017 National road Research Alliance (NRRA) test sections. It was found that the properties of high-density mixtures as a group were not significantly different compared to the properties of conventional mixtures.
Megosztott mobilitás szimulációk Lyon számára
Shared Mobility Simulations for Lyon
Szerző(k): Martinez, O. Petrik
International Transport Forum, OECD
Terjedelem: 93 oldal
This report examines how new shared services could change mobility in Lyon, France. It presents simulations for five different scenarios in which different shared transport options replace privately owned cars in the Lyon metropolitan area. The simulations offer insights on how shared mobility can reduce congestion, lower CO2 emissions and free public space. The analysis also looks at quality of service, cost and citizens’ access to opportunities. The interaction of shared mobility services with mass public transport and optimal operational conditions for the transition are also examined. The findings provide decision makers with evidence to weigh opportunities and challenges created by new shared transport services. The report is part of a series of studies on shared mobility in different urban and metropolitan contexts.
A közlekedés integrálásának keretterve az okos városokban
A Framework for Integrating Transportation into Smart Cities
Szerző(k): Shaheen, A. Cohen, M. Dowd, R. Davis
Mineta Transportation Institute, USA
Terjedelem: 102 oldal
In recent years, economic, environmental, and political forces have quickly given rise to “Smart Cities” — an array of strategies that can transform transportation in cities. Using a multi-method approach to research and develop a framework for smart cities, this study provides a framework that can be employed to: (1) understand what a smart city is and how to replicate smart city successes; (2) the role of pilot projects, metrics, and evaluations to test, implement, and replicate strategies; and (3) understand the role of shared micromobility, big data, and other key issues impacting communities. This research provides recommendations for policy and professional practice as it relates to integrating transportation into smart cities.
Közlekedési rendszerek irányítása egy gyorsan változó világban
Managing Transportation Systems in a Fast-Changing World
Szerző(k): L. Schofer szerkesztő
Transportation Research Board, USA
Terjedelem: 44 oldal
Self-driving cars, rising temperatures and sea levels, increasingly strong weather events, changing citizen preferences, and innovations in technologies that are revolutionizing purchasing behavior, social interaction, financial transactions, communications, and travel – the transportation world is changing very rapidly. Planning for the future is becoming increasingly challenging, because we can no longer look at the past and say the past gives us a strong sense of what the future is going to be like. How do we plan and manage transportation systems in a fast-changing world? How do we make choices about long-life investments in infrastructure in an era where we are facing extreme uncertainty? In this circular we explore these questions from the perspectives of four experts: a senior transportation decision maker; a transportation modeler; a trend spotter in transit and transportation planning; and an historian who specializes in the history of technology and the interaction between technology and society. The results offer ideas for navigating the transportation world ahead. In this collection of four presentations we learned that it is important, though not necessarily easy, for individuals as well as organizations to be prepared for change. A key resource for addressing rapid change is leadership that is willing to recognize and address an uncertain future for transportation systems and service.
Tehergépkocsi utazási idők megbízhatóságának értékbecslése
Estimating the Value of Truck Travel Time Reliability
Szerző(k): S.E. Guerrero, I. Hirschman, J.G.B. Bryan, R.B. Noland, S. Hsieh, D. Schrank, S.B. Guo
WSP, Rutgers University, Abt Associates, Texas A&M Transportation Institute, USA
Terjedelem: 107 oldal
NCHRP Research Report 925: Estimating the Value of Truck Travel Time Reliability provides planners and analysts a Reliability Valuation Framework that is applicable to urban or intercity shipments around the United States across a range of truck freight users and commodity types. Reliability was measured and modeled as the 95th percentile delay, which was defined as the difference between the 95th percentile travel time and the expected travel time. This measure of reliability has various advantages over other measures: it is easy to communicate to shippers and motor carriers, has desirable modeling properties, and is compatible with the Travel Time Index, which is the measure of reliability most commonly used in the United States.
Kerékpárosok és gyalogosok minőségi számlálása
Biking and Walking Quality Counts
Szerző(k): McNeil, K. Tufte
Portland State University, USA
Terjedelem: 63 oldal
Cycling and walking are sustainable modes of transportation which improve community livability, but these modes have not been studied with the quantitative rigor applied to motor vehicle travel. This work aims to change that by improving bicycle and pedestrian traffic monitoring data quality, including how erroneous data can most accurately and efficiently be identified through automated processes. The research approach analyzes continuous bicycle and pedestrian count data stored in BikePed Portal, a data archive of bicycle and pedestrian count data. A primary goal of the project is to explore tests that could help to identify aberrant and/or erroneous data. A key method deployed in pursuit of this exploration was to comb through a selection of count data (generally – continuous counter locations from 2015 to 2016 with at least 30 days of counts) to identify expected count ranges and patterns, overall and broken down by rough expected volume levels, along with counts on the fringe or tail end of expected ranges or patterns. In most cases, potentially bad data would need to be manually checked to confirm or reject the basis for the flag. Thus, a method is proposed to flag suspect data with adjustable scrutiny levels. Individual users may wish to apply higher or lower scrutiny based on their knowledge of the dataset or gained experience with previous data flagging (e.g. if most flagged data is determined to be valid data, the user may wish to lower the level of scrutiny, flagging only data further outside the expected range). Data quality check methods, developed based on empirical counts in BikePed Portal, are proposed to identify appropriate flags for repeated zero values, repeated non-zero values, and maximum/excessive count values.
Tehergépkocsi konvojok hatása az út menti berendezésekre és a járművek biztonságára
Implications of Truck Platoons for Roadside Hardware and Vehicle Safety
Szerző(k): C.S. Dobrovolny, C. Untaroiu, R. Sharma, H. Jin, Y. Meng
Texas A&M Transportation Institute, USA
Terjedelem: 59 oldal
Platooning is an extension of cooperative adaptive cruise control and forward collision avoidance technology, which provides automated lateral and longitudinal vehicle control to maintain short following distances and tight formation. The capacity and adequacy of existing roadside safety hardware deployed at strategic locations may not be sufficient to resist potential impact from an errant fleet of multiple trucks platooning at high speed. It is unknown how these impacting trucks might interact with roadside safety barriers after leaving their platoon and what the occupant risks associated with such impacts may be. This research identifies and prioritizes the critical Manual for Assessing Safety Hardware TL5 roadside safety devices for truck platooning impact assessment in order to understand the associated roadside and occupant risks and hazards. Finite element models of the trucks and roadside safety devices are examined using multiple computer simulations for various scenarios. Occupants injury risks during truck collision simulations are assessed using dummy and human finite element models. The results and implications can provide a better understanding of whether any roadside safety device improvements and/or platooning constraint modifications will be necessary before implementing truck platooning.
Az önvezető járművek kihívásai és lejhetőségei a várostervezésben: a közösségi közlekedés és a parkolás vizsgálata
Challenges and opportunities of autonomous vehicles to urban planning: Investigation into transit and parking
Szerző(k): Wu, F. Douma, J. Cao
University of Minnesota, USA
Terjedelem: 30 oldal
Using a series of qualitative approaches, this report examines the potential impacts of autonomous vehicles (AV) on transit and parking systems. A literature review helped us identify three orders of general impacts caused by the development of AV, as well as their specific effects on transit and parking. Based on the results of the literature review, we organized two focus groups and held in-depth discussions regarding the impacts of AV with planning practitioners from the Minneapolis-St Paul metropolitan area. The analytical results showed that opinions differ regarding what AV’s specific effects might look like. Nevertheless, all of the literature as well as participants of the focus groups agreed that AV will have significant impacts and corresponding planning policies need to be developed.