Nemzetközi szemle: Január
Burkolatok reflexiós repedéseinek kezelését célzó útépítési textília rétegek telepítése és kezdeti értékelése
Installation and Initial Evaluation of Paving Fabric Interlayers for Mitigating Reflective Cracking in Pavements
Szerző(k): H. Nair, J. Habbouche
Virginia Transportation Research Council USA
Terjedelem: 42 oldal
The objective of this study was to establish a performance baseline for fabric interlayers in conjunction with asphalt concrete overlays on existing flexible, rigid, and composite pavements by documenting the installation and initial field performance of several projects in Virginia. Two types of interlayer fabric were used. One of the interlayers needed an asphalt leveling course for placement based on the manufacturer’s specifications. As expected, all of the sections with interlayers are performing well. However, most of the sections were placed in 2017 and 2018, and hence the performance data are preliminary. These sections need to be monitored continuously to track pavement distress and performance over time. The cost of using interlayers in pavement ranged from $6.0 to $8.0 per square yard, depending on the type of fabric and installation method. Long term performance data are needed to assess the benefit-cost effectiveness of using paving fabric interlayers in pavements.
Forgalomirányító jelzőlámpák teljesítmény alapú gazdálkodása
Performance-Based Management of Traffic Signals
Szerző(k): B. Nevers, T. Urbanik, K. Lee, B. Cesme, J. Musselman, L. Zhao, D. Bullock, H. Li, A. Tanaka, C. Day, L. Richardson
Kittelson & Associates, Inc., Purdue University, City of Portland, Iowa State University, Kimley-Horn & Associates, USA
Terjedelem: 208 oldal
Smart City technologies are changing the way agencies manage and operate transportation systems by providing access to more data than has ever been available before. One of the areas where new tools have broadened capabilities is in traffic signal systems. Management of traffic signal systems is a critical function for every transportation agency. Yet while congestion increases and infrastructure ages, funding for equipment and staff resources often remains scarce. The result is that many traffic signals operate with poor timing and/or ill-functioning equipment, leading to unnecessary delays and costs for travelers across all modes. Many agencies are reactive when it comes to monitoring signal performance. Highly-traveled corridors experiencing poor performance are often identified only after travelers have endured frustration for an extended period. When service requests arrive, traffic signal managers and staff are often unable to validate the information. Thanks to advancements in technology, it is now possible to collect large amounts of data at signalized intersections, leading to the development of dozens of performance measures. Where agencies previously had little to no information about equipment health or intersection operations, they can now review cycle-by-cycle events and initiate dashboard reporting and automated alerts. Signal performance measures profoundly change all aspects of traffic signal operations from planning to design and implementation through better-informed, data-driven decisions. This guidebook provides information to help agencies invest in signal performance measures as part of a comprehensive approach to performance-based management.
Államközi autópálya folyosók kapacitás változásának értékelése az önvezető járművek hatására
Assessment of Capacity Changes Due to Automated Vehicles on Interstate Corridors
Szerző(k): K. Heaslip, N. Goodall, B. Kim, M. Abi Aad
Virginia Transportation Research Council USA
Terjedelem: 85 oldal
This study was designed to assess capacity changes due to the introduction of connected vehicles (CVs) and automated vehicles (AVs) on Virginia freeway corridors. Overall, three vehicle types, including legacy vehicles (LVs); vehicles equipped with adaptive cruise control (ACC) (AVs); and vehicles equipped with cooperative adaptive cruise control (CACC) (connected automated vehicles [CAVs]), were considered in mixed traffic scenarios. Each scenario included light-duty passenger vehicles and heavy vehicles (HVs) with AV and CAV capabilities to determine their overall effect on capacity. The team developed an AV and CAV driving behavior model and evaluated it on a test network. According to the testing results, the 100% AV and 100% CAV scenarios increased road capacity by 28% and 92% over the 100% LV scenario, respectively, on a basic freeway segment with intermediate vehicle behavior. Moreover, in the case of the HV scenario, AVs and CAVs showed a substantial capacity increase. Simulations were also conducted on models of I-95 in Virginia, where AVs and CAVs improved capacity compared to LVs. However, in some scenarios during congested conditions, AVs performed worse than LVs with reduced speeds and increased travel times because of the frequent stop-and-go conditions because of short headways. This issue was mitigated with the implementation of CAVs because of their ability to communicate and increase string stability. Under uncongested conditions, AVs and CAVs improved throughput and reduced delays as compared to LVs but caused a small decrease in speeds and an increase in travel times. Additional simulations were performed on models of I-81 to test the effects of extended grades and high percentages of HVs, where AVs and CAVs were found to have a high potential of improving operations when compared to LVs. The presence of steep grades negatively affected the performance of all types of vehicles, especially HVs, when compared to flat terrain. CAVs with their communication capabilities, particularly at high market penetrations, were capable of achieving capacity increases over AV and LV scenarios in the selected I-81 segment. AVs and CAVs proved capable of improving highway operations. Even in the presence of high percentages of HVs and steep grades, vehicles equipped with AV and CAV technologies provided better performance than LVs. Ultimately, AVs and CAVs need full market penetration to operate at their maximum potential. However, these technologies, even in mixed traffic, could still offer operational benefits at lower penetrations.
Városi határok. Biztonságos sebességhatárok megállapítása a városi utakon
City Limits. Setting Safe Speed Limits on Urban Streets
Szerző(k): NACTO National Association of City Transportation Officials USA
Terjedelem: 50 oldal
This document, City Limits, is intended to provide city practitioners with guidance on how to strategically set speed limits on urban streets, using a Safe Systems approach, to reduce traffic fatalities and injuries. Recognizing that city authority to set speed limits varies by jurisdiction, City Limits offers three tools for setting speed limits on urban streets: Setting Default Speed Limits on many streets at once. Designating Slow Zones in sensitive areas. Setting Corridor Speed Limits on high priority major streets using a Safe Speed Study. City Limits maps a new path for US cities, codifying speed limit setting best practices that have been tested and documented in cities across North America. Cities can create better and safer outcomes for all by adopting these speed limit setting practices as part of their traffic fatality reduction or Vision Zero programs. By managing speeds, cities can save lives.
Döntést segítő útmutató forgalomirányító jelzőlámpás fázisosztáshoz
Decision-Making Guide for Traffic Signal Phasing
Szerző(k): C. Daily, M. Tantillo, P.J. Chun, N. Wilcox, C. Conran, M. Cynecki, R. Dittberner, C. Lyon, D. Noyce, M. Chitturi, B.C. Rodriguez
VHB, Lee Engineering, Persaud and Lyon, University of Wisconsin, USA
Terjedelem: 83 oldal
This guide documents and presents the results of a study of traffic signal phasing. The guide synthesizes existing best practices as well as new information from the accompanying research effort (NCHRP 03-118). This guide covers right-turn, left turn, and pedestrian phasing mode and sequence concepts. Concept definitions and best practices are provided for right-turn and pedestrian phasing mode and sequence. For left-turn phasing, this guide summarizes the concepts / existing best practices and includes additional information from the accompanying research effort (NCHRP 03-118). The guide presents safety performance functions (SPFs) and crash modification factors (CMFs) for left-turn phasing modes as well as charts to determine the operational impact of each phase mode. A methodology for combining the effect of safety and operations of the various left-turn phase modes is also provided in this guide.
Integrált multimodális közlekedési folyosó menedzsment tervezése és megvalósítása: Útmutató
Planning and Implementing Multimodal, Integrated Corridor Management: Guidebook
Szerző(k): K.T. Miller, V. Alexiadis, A. Chu, J. Ticatch, A. Shah, A. Phaneuf, T. Huang
Kapsch TrafficCom, Cambridge Systematics, Kimley-Horn and Associates, Inc., USA
Terjedelem: 122 oldal
For system operations and maintenance, stakeholders should realize that the system is always evolving. Crash patterns and travel patterns are always changing due to construction, changes in the economy, and changes in your transportation network. Stakeholders need to be flexible and understand that Integrated Corridor Management (ICM) is a process, and that it takes time and rigor to ensure the ICM evolves as traveler needs within the region change.
A nehéz tehergépkocsik és az engedélyezett túlsúlyok hatása az utakra és hidakra most és a jövőben, összevetve a túlsúlydíjakkal, a tehergépkocsi regisztrációs díjakkal és az üzemanyag adókkal
Impact of Heavy Trucks and Permitted Overweight Loads on Highways and Bridges Now and in the Future versus Permit Fees, Truck Registration Fees, and Fuel Taxes
Szerző(k): H. Ali, A.S. Nowak, J.M. Stallings, J. Chmielewski, S. Stawska, A. Ramesh Babu, F. Haddadi
Florida International University USA
Terjedelem: 204 oldal
In this study, a damage assessment approach was developed to calculate the monetary consumption caused by overweight permitted vehicles on bridges and pavements in Florida. The damage assessment analysis for the bridges was conducted based on the fatigue damage measured by the equivalent bending moment on a representative bridge in Florida. Results of the bridge consumption analysis are given in $/miles. To calculate pavement damage cost, life cycle cost and damage analysis were rendered for 37 different representative road segments in Florida. The pavement damage was presented based on the equivalent single axle loads (ESALs). Then, a model was developed to estimate the average pavement damage for a given number of ESALs. The pavement and bridge damage costs were combined and presented in the same format as the existing overweight permit fee structure. Comparing the proposed permit fee to the current Florida fees showed that the proposed fees will increase the revenues of single-trip permits by a factor of 1.6, multi-trip 12-month months permits by a factor of 1.5, and multi-trip 3-month permits by a factor of 2.7. This is based on a 90% discount for multi-trip permits. The department can choose an appropriate discount rate for multi-trip permits based on economic considerations. The proposed change brings Florida’s overweight permit fees more in line with those of other states.
A gyalogos fogyasztói szolgáltatási szintet javító módszerek fejlesztése
Developing methodologies for improving customer levels of service for walking
Szerző(k): A.M. Head, R. Tuke, D. Smith
Abley Limited, New Zealand
Terjedelem: 87 oldal
This study sought to develop a walking level of service framework to support better decision making when providing for pedestrians by focusing on the barriers and motivators to walking. The framework is based around factors that are important to pedestrians so these are all considered within the planning, design and operation of the transport network. Qualitative customer insights research informed the development of a Pedestrian Level of Service Framework for New Zealand. This framework and an accompanying online assessment tool were developed in collaboration with transport practitioners as a starting point for a consistent approach to measuring and evaluating pedestrian level of service in urban areas of New Zealand. The framework applies to street families within a movement and place functional street classification and consists of 19 metrics that contribute to five pedestrian level of service outcomes. The framework includes both safety and amenity drivers that are fundamental to people walking. The proposed assessment tool, once validated, will support smarter decision making around street environments to encourage walking, and contribute to more liveable and vibrant communities.