<?xml version="1.0" encoding="utf-8"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>TRB Publications Index</title><link>http://pubsindex.trb.org/</link><atom:link href="http://pubsindex.az.trbvpc.org/common/TRIS Suite/feeds/rss.aspx?cdatein=1year" rel="self" type="application/rss+xml" /><description></description><language>en-us</language><copyright>Copyright © 2015. National Academy of Sciences. All rights reserved.</copyright><docs>http://blogs.law.harvard.edu/tech/rss</docs><managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor><webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster><image><title>TRB Publications Index</title><url>http://pubsindex.trb.org/Images/PageHeader-wTitle.png</url><link>http://pubsindex.trb.org/</link></image><item><title>Real Time Traffic Signal System Instrumentation Using National Electrical Manufacturers Association TS2 Synchronous Data Link Control Networks</title><link>http://pubsindex.trb.org/view/1337895</link><description><![CDATA[In this paper, a method of real time traffic signal instrumentation is introduced and described. Current practices of cabinet instrumentation methods require physical electrical connections to each traffic signal being instrumented. These methods are labor intensive to install and require a certified technician in certain states due to the 120VAC signals used. The new method obtains information concerning the traffic signal status derived from existing equipment within National Electrical Manufacturers Association (NEMA) TS2 traffic cabinets by monitoring the Synchronous Data Link Control (SDLC) network. Using the SDLC interface reduces the risk associated with high voltage allowing for a more time efficient installation. The SDLC, being critical to this approach to instrumentation, is described in detail as to allow the reader to understand the mechanism to retrieve the desired information. A case study demonstrates the proposed SDLC-based instrumentation method with an Advanced Accessible Pedestrian Systems (AAPS). Comparisons between the proposed SDLC method and current methods of traffic signal instrumentation showed that the decoding time of sensing a traffic signal state in the new method is more consistent with devices already in the traffic cabinet. It is demonstrated that using a single large scale integrated circuit based design has higher component reliability than a design with multiple small scale integration devices. This new method can be used in other traffic signal system applications such as an SDLC Interface Device or a device to log the state of different input/output channels at the signalized intersection.]]></description><pubDate>Fri, 03 Apr 2015 16:39:52 GMT</pubDate><guid>http://pubsindex.trb.org/view/1337895</guid></item><item><title>Generation of Mandatory Activities and Formation of Mandatory Tours: Application to the Activity-Based Model for Phoenix, AZ</title><link>http://pubsindex.trb.org/view/1339065</link><description><![CDATA[Most activity based models (ABMs) in practice generate tours first and then predict details of intermediate stops. However, the basic unit of travel analysis in ABM system is an activity. This central idea is somewhat lost in many ABM designs in both research and practice. This paper outlines an approach to model daily travel in ABMs by generating activities first and then forming tours. This approach is based on the idea that higher priority activities are scheduled first and other activities are built around these prioritized activities. There are four steps to this approach – formation of mandatory tour skeletons, participation in shared non-mandatory activities, allocation of individual non-mandatory activities to day segments, and lastly activity sequencing and tour formation. This paper focuses on the first step. Traditionally, a person with a mandatory daily activity pattern was assumed to have a single commuting tour to the usual workplace. However, in reality a significant number of workers pursue multiple work-related activities, including non-workplace (business) activities. Some previously developed ABMs tackled this issue by incorporating a mandatory tour frequency model. This approach distinguishes business activities from the regular workplace activities. First the frequency and chronological ordering of workplace/business activities is modeled, and then the location of business activities, and finally the tour breakdown decision. These models make the ABM system behaviorally more realistic and more useful in practice since they address certain travel markets like “midday business circulation” in urban business districts that are largely missing in most travel models.]]></description><pubDate>Mon, 30 Mar 2015 12:22:11 GMT</pubDate><guid>http://pubsindex.trb.org/view/1339065</guid></item><item><title>Operational Performance Comparison of Limited-Access and Continuous-Access HOV Lane Facilities</title><link>http://pubsindex.trb.org/view/1339299</link><description><![CDATA[High-Occupancy Vehicle (HOV) lanes have been regarded as a cost-effective and environmentally friendly option to help move people along congested routes in metropolitan areas. HOV lanes can be categorized as continuous-access and limited-access based on accessibility. This paper focused on the comparison of the operational performance of four study sites in which conversion of HOV lanes from limited-access to continuous-access has taken place. This paper proposed a traffic flow fundamental diagram based approach in which a statistical approach was applied to estimate the traffic flow fundamental diagram parameters, including free-flow speed, critical volume, critical volume and shockwave speed, for the study. The general-purpose lanes' traffic flow fundamental diagram parameters before and after the conversion were further used to evaluate the performance of the HOV lane conversion. Results show that (1) the HOV lane conversion leads to a faster shockwave speed on general-purpose lanes during the traffic congestion and thus a freeway with continuous-access HOV lane would see congestion clear faster; (2) the performance of the critical volume and critical occupancy after conversion is site-specific and influenced by the local geometric attributes and associated traffic patterns]]></description><pubDate>Mon, 30 Mar 2015 09:35:26 GMT</pubDate><guid>http://pubsindex.trb.org/view/1339299</guid></item><item><title>NCHRP Synthesis: Active Traffic Management Strategies for Arterials</title><link>http://pubsindex.trb.org/view/1344096</link><description><![CDATA[In July 2013, the National Cooperative Highway Research Program (NCHRP) published a synthesis project entitled Active Traffic Management for Arterials, which provides an overview of strategies associated with designing, implementing, and operating active traffic management (ATM) on arterials. This article describes the project and details a number of its findings. The survey revealed challenges to ATM project implementation, and the article identifies particular areas where additional research is needed.]]></description><pubDate>Fri, 20 Mar 2015 15:06:28 GMT</pubDate><guid>http://pubsindex.trb.org/view/1344096</guid></item><item><title>Ballast Settlement Ramp to Mitigate Differential Settlement in a Bridge Transition Zone</title><link>http://pubsindex.trb.org/view/1337310</link><description><![CDATA[Differential settlement in railroad track transitions, often associated with differences in track stiffness, may apply considerable impact load and cause rapid track geometry deterioration. Such a differential settlement commonly seen in bridge approaches may lead to problems associated with ride comfort, track safety and reliability. Ballast and subballast layers have been identified as a major cause of differential settlement due to the particulate nature of the aggregate deformation behavior causing potential degradation and breakdown associated with increased track usage. This paper describes an innovative field approach which successfully demonstrated the use of engineered ballast materials for reducing/mitigating the differential settlement problem in a bridge transition zone. Discrete Element Method (DEM) simulations were employed to predict full scale track deformations of four ballast materials, each having different gradations and aggregate shape properties. The ballast aggregate shape properties, i.e., particle flatness and elongation and angularity, were measured and quantified by indices using an imaging device to create accurate particle size distributions and shapes. Based on the DEM modeling study results, a bridge approach settlement ramp was constructed and tested at the Transportation Technology Center Facility for Accelerated Service Testing (FAST) facility. The results show the “settlement ramp” approach can be achieved by constructing ballasted track with proper selection of materials in each section of track transition zone. This study also demonstrates that the DEM simulation approach combined with image analysis has the potential to be a quantitative tool to predict the ballast performance and provide much needed help in track transition designs.]]></description><pubDate>Thu, 12 Mar 2015 07:53:11 GMT</pubDate><guid>http://pubsindex.trb.org/view/1337310</guid></item><item><title>The Influence of the Frequency-Dependent Dynamic Parameters of Rail Pad on Environment Vibration Induced by Subway in Tunnel</title><link>http://pubsindex.trb.org/view/1336725</link><description><![CDATA[Based on verification of a new frequency-domain algorithm by the measured data, the influence of frequency-dependent dynamic parameters of rail pad on environment vibration is investigated. The contrast between the theoretical and the measured data shows that the new approach are reasonable and provided with high calculation accuracy in frequency range. The effect of frequency-dependent stiffness of rail pad on environment vibration can be neglected below the 1/3 octave center frequency of 25Hz, and yet alters not only the frequency-domain amplitudes of environment vibration but also its frequency distribution above 25Hz. The frequency-dependent damping of rail pad slightly increases the maximum ground vibration level in 1/3 octave frequencies, and yet reduces the ones above the 1/3 octave center frequency with the maximum. Simply to increase the constant stiffness of rail pad or to decrease its constant damping can make the predicted ground vibration endowed with smallest error in either the low-frequency or the high-frequency domain. With continuous deterioration of track irregularity, regardless of frequency-dependent dynamic parameters of rail pad, the constant stiffness or damping of rail pad with smallest error is not invariable.]]></description><pubDate>Wed, 11 Mar 2015 09:09:54 GMT</pubDate><guid>http://pubsindex.trb.org/view/1336725</guid></item><item><title>Process and Data Needs for Local Calibration of Performance Models in the Pavement-ME</title><link>http://pubsindex.trb.org/view/1339182</link><description><![CDATA[The local calibration of the performance models in the Pavement-ME is a challenging task, especially if the data are limited. This paper summarizes the local calibration process for flexible and rigid pavements for the state of Michigan. However, other agencies can learn from the steps needed to accomplish a more streamlined local calibration. The local calibration process includes several sequential steps. Statistical sampling concepts were used to determine the adequate number of pavement sections for a robust calibration. The next step is to identify the candidate pavement sections in the pavement management systems (PMS) database based on the pavement type, age, geographical location, and number of performance data collection cycles. Subsequently, the final set of pavement sections is selected based on the distress magnitude over time. It is important to categorize the selected pavement sections based on the measured distresses (i.e., poor, normal and good performing pavements) because the local calibrated models are typically used to predict normal pavement performance at the design stage. For the selected pavement sections, the as-constructed input variables are collected from the construction records. However, when such input information is unavailable, the best estimates are used to represent Michigan Department of Transportation (MDOT) pavement design and construction practices. Lastly, the typical steps for local calibration (verification, calibration and validation) by using various resampling techniques are demonstrated for the rutting (flexible) and transverse cracking (rigid) models. The different techniques are compared by using the standard error of the estimate (SEE). The SEE of a technique shows how much of the variance is explained by the model. The main advantage of using repeated resampling is to quantify the variability associated with the model predictions and parameters. The quantification of the variability will also help in determining more robust design reliability in the Pavement-ME.]]></description><pubDate>Tue, 10 Mar 2015 07:50:32 GMT</pubDate><guid>http://pubsindex.trb.org/view/1339182</guid></item><item><title>Soft Rising Bollard – Flexible Device to Improve Road Environment</title><link>http://pubsindex.trb.org/view/1336608</link><description><![CDATA[In this study, the authors focused on rising bollards, which allow selective traffic on regulated public roads using one or more bollards that move up and down. Bollard systems, which are used in many European countries, were originally developed to guard against terrorism but have led to new traffic problems in countries where they are used. The authors conducted surveys in several municipalities in European countries to identify the advantages and disadvantages of rising bollard systems and solicit suggestions for improving rising bollard systems. The results of the survey reveal that rising bollard systems are effective in reinforcing traffic regulations in city centers but that many authorities face difficulties related to collisions with bollards by unauthorized vehicles that violate traffic regulations. To address this problem, the authors developed a new type of rising bollard that is soft and flexible. When a vehicle collides with this type of bollard, the bollard does not damage the vehicle and does not break; it bends so that the vehicle can pass over it. A social experiment was conducted to test the effectiveness of the system. The results of the experiment show that the soft rising bollard system was effective in encouraging vehicles to obey a traffic regulation that prohibited vehicles from using a road during certain hours of the day. The results suggest that the soft rising bollard system developed in this study could be a new tool for traffic control on pedestrian-friendly roads.]]></description><pubDate>Thu, 26 Feb 2015 10:05:23 GMT</pubDate><guid>http://pubsindex.trb.org/view/1336608</guid></item><item><title>A Peer-to-Peer Matching System for Grocery Home Delivery</title><link>http://pubsindex.trb.org/view/1337544</link><description><![CDATA[This paper introduces a new delivery method for electronic grocery shopping. This method involves a peer-to-peer matching system in which customers (carriers) who shop at a grocery store are assigned other customers (clients) who have ordered groceries online. Carriers deliver groceries to the clients’ homes, in return for an incentive. The authors' proposed system matches carriers with clients to minimize the total travel time on the network. In order to examine how this new delivery method performs, the authors compare it with existing methods of grocery shopping and delivery. The authors' proposed system performs well in terms of reducing total travel time and has the potential to be implemented alongside the two current methods of grocery shopping; regular shopping and truck delivery. While the matching system reduces total travel time compared to regular grocery shopping, it does not outperform truck delivery service. The performance of the matching system is best when the number of carriers is equal to the number of clients.]]></description><pubDate>Thu, 26 Feb 2015 10:03:43 GMT</pubDate><guid>http://pubsindex.trb.org/view/1337544</guid></item><item><title>Can Protected Bike Lanes Help Close the Gender Gap in Cycling? Lessons from Five Cities</title><link>http://pubsindex.trb.org/view/1338129</link><description><![CDATA[Even in areas with increased levels of bicycling, there remains a significant “gender gap” in bicycling in the United States, in contrast to many other countries with high rates of bicycling. The primary objective of this paper was to explore whether protected bike lanes could help reduce the gender gap. To do so, the authors used survey data from a comprehensive evaluation of protected bike lanes in five large U.S. cities (Austin, TX, Chicago, IL, Portland, OR, San Francisco, CA, and Washington, DC) that included survey responses of 1,111 intercepted bicyclists and 2,283 residents. Both men and women overwhelmingly felt that the lanes increased their safety while riding in them. On several measures of safety and comfort, women bicyclists using the lanes did have significantly more positive associations with the protected lanes than men. A survey of residents, which included people who do and do not bicycle, revealed that women generally feel less comfortable than men bicycling on roadways, though the addition of some physical separation to a striped bike lane, does increase stated levels of comfort to a level that might increase rates of bicycling. Overall, women were also more likely to indicate that the new protected lane had increased their overall levels of bicycling. Analysis of the demographics of the intercepted bicyclists revealed differences between men and women that point to the challenge of increasing women’s rates of bicycling, primarily that the women intercepted bicycling were much less likely than men to have children.]]></description><pubDate>Thu, 26 Feb 2015 10:03:41 GMT</pubDate><guid>http://pubsindex.trb.org/view/1338129</guid></item><item><title>Self-Heating Electrically Conductive Concrete for Pavement Deicing: A Revisit</title><link>http://pubsindex.trb.org/view/1338831</link><description><![CDATA[The addition of conductive materials to conventional concrete to achieve electrically conductive concrete (ECC) for non-structural applications such as heating (deicing), sensing, monitoring, and electromagnetic interference shielding has been the subject of many studies in the past. The overall objective of this paper is to revisit the topic of self-heating ECC for pavement deicing applications, especially with the focus on conductive concrete mix design optimization. The paper discussed related studies reported in the literature to identify the various conductive materials that have been investigated in the past, their optimal concentration levels to achieve desirable system-level engineering properties, and the various challenges in optimizing the ECC mix design and achieving a cost-effective ECC system. These studies reveal that optimization of ECC mix design, to achieve high conductivity and at the same time maintain adequate mechanical properties (workability, strength, and durability), is a highly challenging task. Instead of using large quantities of single conductive material to achieve well-performing ECC, which can be not only expensive but also result in reduced strength properties, the combined use of various conductive materials (especially the combination of conductive fibers and powders) in concrete has the potential to achieve cost-effective and well performing ECC with adequate electrical and mechanical properties.]]></description><pubDate>Thu, 26 Feb 2015 10:03:31 GMT</pubDate><guid>http://pubsindex.trb.org/view/1338831</guid></item><item><title>Freight Traffic Assignment Methodology for Large-Scale Road–Rail Intermodal Networks</title><link>http://pubsindex.trb.org/view/1338597</link><description><![CDATA[A methodology is proposed for freight traffic assignment in large-scale road–rail intermodal networks. To obtain the user–equilibrium freight flows, a path-based assignment algorithm (gradient projection) was proposed. The developed methodology was tested on the U.S. intermodal network by using the 2007 freight demand for truck, rail, and road–rail intermodal from the Freight Analysis Framework, Version 3 (FAF3). The results indicate that the proposed methodology’s projected flow pattern is similar to the FAF3 assignment. The proposed methodology can be used by transportation planners and decision makers to forecast freight flows and to evaluate strategic network expansion options.]]></description><pubDate>Thu, 26 Feb 2015 09:49:47 GMT</pubDate><guid>http://pubsindex.trb.org/view/1338597</guid></item><item><title>Competitive Industry Clusters and Transportation in Minnesota: An Exploratory Study</title><link>http://pubsindex.trb.org/view/1338714</link><description><![CDATA[This project seeks to advance the state of knowledge of the relationship between transportation and economic development by investigating how firms in competitive industry clusters use transportation networks and what role those networks play in the competitiveness of these clusters. The approach combines quantitative and qualitative techniques to geographically identify competitive industry clusters and to investigate the role of transportation. The U.S. Cluster Mapping tool is used to identify competitive clusters by employment location quotients in 25 Minnesota metropolitan and micropolitan regions. Twelve competitive clusters were selected for further study, and in-depth interviews and site visits were conducted with businesses in each cluster to explore the competitive importance of different modes of transportation. These methods can yield valuable insights into how transportation functions as an input within competitive industry clusters and how it can inform economic development strategies tailored to certain locations and industries.]]></description><pubDate>Thu, 26 Feb 2015 09:49:31 GMT</pubDate><guid>http://pubsindex.trb.org/view/1338714</guid></item><item><title>Rheological Indexes: Phenomenological Aspects of Asphalt Binder Aging Evaluations</title><link>http://pubsindex.trb.org/view/1337193</link><description><![CDATA[An investigation into several of the commonly utilized rheological indices and their influence on oxidation studies was conducted. The evaluation considered the Low-Shear Viscosity (LSV), dynamic shear rheometer (DSR) function or Glover-Rowe parameter, the shear crossover modulus (G* sub c) value, as well as parameters from both the Williams-Landel-Ferry (WLF) and Kaelble shift functions, the rheological indices for comparative oxidation characterizations of two example asphalt binders. In general, each respective methodology was found to correlate with increasing levels of oxidation, but resulted in differing outcomes with respect to oxidation depending upon the evaluation methodology used. While each method presents its own merit and respective limitations, a single preferential method was not readily identified. However, the critical need for reliable and sound rheological measures and data processing procedures was clearly demonstrated. This evaluation has supported the need for a clear and logical evaluation of the rheological parameters utilized to characterize asphalt binders. It has been documented that certain rheological indices have strong correlations to specific distress types or mechanical behaviors and thus may prove beneficial to a particular analysis. However, evaluations must also acknowledge the limitations of selected techniques. If possible, complete characterization through means of the development of full master curves may be beneficial. With sound rheological data and comprehensive measures, several indices can be determined and provide a more comprehensive view of the investigated material responses.]]></description><pubDate>Wed, 25 Feb 2015 10:23:05 GMT</pubDate><guid>http://pubsindex.trb.org/view/1337193</guid></item><item><title>Performance Trends on Interstate Highway Sections of Long-Term Pavement Performance Program</title><link>http://pubsindex.trb.org/view/1339416</link><description><![CDATA[The Moving Ahead for Progress in the 21st Century (MAP-21) Act requires the Federal Highway Administration (FHWA) to identify pertinent performance measures and establish minimum acceptable levels for the condition of pavements on the National Highway System (NHS). Due to differences in data collection and analysis among State Highway Agencies (SHA), a comparison of the performance data from different states is not viable. Although the Long-Term Pavement Performance (LTPP) sections are spread across various states, all of the sections have been monitored according to the same standards. Using LTPP data, analyses were conducted to gain insight into actual deterioration rates and the impact of maintenance and rehabilitation (M&amp;R) activities on the performance of Interstate highway pavements. From evaluating the decline in longitudinal and transverse profiles (roughness and rutting), it was noted that about 90% of pavement sections have experienced nominal changes from year to year. This trend remains consistent across pavement type, time, and state lines. It is apparent that the SHA have been proactively applying pavement preservation strategies where these nominal improvements are being realized. It is not imperceptible, however, that these nominal deviations could be associated with changes in the sections themselves, likely due to climatic, environmental, traffic or other loading conditions. The average annual rate of roughness progression for flexible pavements increases when the surface ages from zero up to twelve years old. The highest annual International Roughness Index (IRI) increase rate occurs when the surface is between eight and twelve years old for flexible pavements, and between sixteen and twenty years old for rigid pavements. The percentages of significant annual changes (more than 20 percent), were approximately the same between increasing and decreasing IRI rates. This could mean that the SHA have been addressing roughness with proper treatments, at the same rate as roughness has been progressing. For rigid pavements, asphalt concrete (AC) overlay, transverse joint sealing and surface grinding are the predominant treatments that decrease IRI. For flexible pavements, overlay or mill and overlay are the most predominant treatments effective in reducing IRI. In agreement with previous research findings, milling before overlay has increased the average IRI reduction. Unlike roughness, it seems that milling before overlay does not improve the effectiveness of overlays in reducing rutting.]]></description><pubDate>Mon, 09 Feb 2015 16:31:43 GMT</pubDate><guid>http://pubsindex.trb.org/view/1339416</guid></item></channel></rss>