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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <title>Empirical Before-After Comparison of the Operational Performance of Diverging and Conventional Diamond Interchanges</title>
      <link>https://trid.trb.org/View/1403542</link>
      <description><![CDATA[A diverging diamond interchange (DDI), also known as a double crossover diamond interchange, is an unconventional interchange design. The DDI design is able to accommodate heavy left-turn demand more efficiently than conventional diamond interchanges by switching directions of travel for the arterial through movements. The first DDI in the United States opened in 2009, with approximately 37 currently in operation and hundreds more under construction or in the planning phases. This paper presents an empirical analysis of before and after field data collected at two sites under Federal Highway Administration (FHWA) project DTFH61-10-C-00029, Field Evaluation of Double Crossover Diamond Interchanges. Operational performance data assessed in this paper include traffic volume, saturation flow rate, queue length, delay, and travel time. The study focused on the before and after evaluation of two conventional diamond interchanges at Front Street and I-435 in Kansas City, MO, USA, and at Winton Road and I-590 in Rochester, NY, USA. The field data analysis reveals that DDIs generally operate more efficiently than their conventional diamond interchange counterparts. The Kansas City site had considerable savings in queue lengths and delays for all directional movements, while the Rochester site’s queue lengths and delays indicated somewhat mixed results, showing improvements in a specific directional movement like left turns from the arterial, but exhibiting deterioration in other, less notable movements.]]></description>
      <pubDate>Thu, 28 Apr 2016 14:43:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1403542</guid>
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      <title>Quantifying Safety and Economic Impacts of Texas Travel Information Centers</title>
      <link>https://trid.trb.org/View/1403540</link>
      <description><![CDATA[The study summarized by this paper was to develop a methodology and gather sufficient data to quantify the increase in safety for travelers and the economic benefits due to travel information centers (TICs) on the Texas Department of Transportation roadway network. Visitor surveys conducted at the TICs suggest that TICs provide substantial economic benefits, and, when interpreted through a safety index, also suggest that TICs provide a significant increase in traveler safety. Analysis of crash data provides further evidence that TICs increase traveler safety, as the decrease in crash rates in traffic having access to TICs is significantly lower.]]></description>
      <pubDate>Thu, 28 Apr 2016 14:43:16 GMT</pubDate>
      <guid>https://trid.trb.org/View/1403540</guid>
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      <title>Modeling Telecommuting Decisions in Diverse Socioeconomic Environments</title>
      <link>https://trid.trb.org/View/1403545</link>
      <description><![CDATA[This paper advances a Bayesian model that can explain how a potential commuter decides whether to telecommute or not and identifies the optimal option under defined personal, work, and traffic conditions. The variables that influenced the development of the model include urban structure, employer policy regarding telecommuting, personal utility structure of potential telecommuter, and traffic conditions that are encountered in regular commuting. For the sake of realism, the model is applied to the National Capital Area (Canada), where attitude survey, land use, and travel data are available. The results show that the Bayesian model has the potential to account for diverse socioeconomic environments under which telecommuting decisions are made. The model can be used by a potential telecommuter to identify the most favorable telecommuting option. Private and public sector organizations can apply the model to infer the acceptance of telecommuting by employees whose jobs are potentially suitable for telecommuting. Parts of this paper were presented at conferences, but these were not published.]]></description>
      <pubDate>Thu, 28 Apr 2016 14:43:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1403545</guid>
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      <title>Traffic Pattern Groups Based on Hourly Traffic Variations in Urban Areas</title>
      <link>https://trid.trb.org/View/1403518</link>
      <description><![CDATA[Urban traffic monitoring programs commonly utilize short-duration counts, including counts less than 24 hours in duration. For certain applications, it is necessary to estimate daily traffic volume from these counts. This requires the application of hourly factors derived from traffic pattern groups (TPGs) that comprise count sites with similar hourly traffic patterns and that also share features that generate these patterns. This article applies a hybrid approach to developing TPGs based on hourly traffic variations. The hybrid approach integrates the results of a statistical cluster procedure with pragmatic knowledge about the underlying variables that account for statistical similarities. The analysis shows that roadway functional class (e.g., local, collector, and arterial classifications), traffic volume, and land use characteristics (e.g., residential, commercial, and industrial uses) help explain hourly variations and are thus appropriate variables to distinguish the TPGs used in the factoring process. Application of the approach using data collected in Winnipeg, Manitoba, Canada, results in the identification of six TPGs that exhibit hourly traffic patterns generated by unique combinations of values of the three explanatory variables investigated. More broadly, the results illustrate how urban jurisdictions can better leverage readily available partial-day traffic counts to meet the growing demand for traffic information.]]></description>
      <pubDate>Thu, 28 Apr 2016 14:43:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/1403518</guid>
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    <item>
      <title>Comparing Perceived and Actual Travel Time Savings on Freeways with Managed Lanes</title>
      <link>https://trid.trb.org/View/1323901</link>
      <description><![CDATA[Respondents to a 2010 revealed preference survey were asked questions related to their  recent travel on Houston’s Katy Freeway (Houston, TX, USA). One question asked if they  experienced any travel time savings by using the new Katy Managed Lanes (MLs). This study  examined any difference between their perceived and actual travel time savings. This study found  that travelers overestimated the travel time savings they experienced by traveling on the MLs by  a factor of 4. The magnitude of misperception varied with individuals, but the average individual  saved approximately 3 minutes and thought they saved nearly 12 minutes. Linear regression  models were fit to model the misperception of the travel time savings and found that both trip  characteristics and respondent socioeconomic characteristics had an effect on the magnitude of  misperception of travel time savings. Respondents’ trip purpose, gender, and income were found  to be significant predictors of how well they estimated their travel time savings.]]></description>
      <pubDate>Fri, 26 Sep 2014 14:24:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/1323901</guid>
    </item>
    <item>
      <title>A Methodology Using GPS to Inventory University Campus Parking</title>
      <link>https://trid.trb.org/View/1323924</link>
      <description><![CDATA[Global positioning systems (GPSs) have been used by both public and private entities to  collect the locations of transportation assets and other spatial data including traffic signs, bus  stops, bridges and culverts, and incident locations. In combination with geographic information  systems, GPS data enable asset managers to track changes in assets and conduct “what if”  assessments to aid in improved system management. This research explores the use of GPS  to inventory individual parking space data, and subsequently generate a geospatial parking  management system for Clemson University. On a growing college campus, with new buildings  now occupying former surface parking lots and peak parking utilization rates reaching 95  percent, accurate and aggressive management of this commodity is a priority.  While handheld GPS data collection devices provide opportunities to locate individual  parking spaces for development of comprehensive space-by-space parking inventory maps,  most published parking inventory studies have been conducted with pen and paper, limiting  data to counts by lots or street segments. Collecting GPS locations for individual parking  spaces provides a unique challenge due to the relative proximity of one space to another.  Even small spatial errors that are inherent in GPS data collection not only are apparent but  could compromise effective use of the data. This research combines the use of Wide Area  Augmentation System–enabled GPS with digital aerial/satellite imagery and computer-aided design (CAD) as-built drawings to locate and inventory individual parking spaces. A  methodology was developed to enhance the GPS locations to match the underlying CAD and  aerial maps.]]></description>
      <pubDate>Fri, 26 Sep 2014 14:24:34 GMT</pubDate>
      <guid>https://trid.trb.org/View/1323924</guid>
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    <item>
      <title>The Effect of Additional Lane Length on Double-Lane Roundabout Operation</title>
      <link>https://trid.trb.org/View/1323927</link>
      <description><![CDATA[The purpose of this paper is to provide insight as to how additional lane length on an  approach and/or departure affects roundabouts. Currently, there is no United States guideline on  how additional lane lengths affect roundabout operation, so most transportation professionals refer  to studies conducted overseas that do not necessarily translate directly to domestic roundabout  design and operation. As the number of modern roundabouts in the United States continues to  increase, the desire is to provide effective information to professionals on roundabout operation and  design for conditions suitable for their jurisdiction. Using delay as the measure of effectiveness, a  hypothetical four-leg, double-lane roundabout with additional lane length design at both entry and  exit was analyzed, and the additional lane lengths were varied at both the entry and exit. Similar length  variations were applied to an existing roundabout with known data after calibration and validation.  The findings from this study are intended to provide transportation professionals with the quantitative  means of improving existing roundabout operational performance and also help design future  roundabouts with appropriate additional lane lengths that yield better performance. While the design  of an additional lane differs from a flared entry, findings from this study can also be applied to flare  lengths if they are designed to operate in a similar fashion as additional lane entry.]]></description>
      <pubDate>Fri, 26 Sep 2014 14:24:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1323927</guid>
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    <item>
      <title>Transforming the Washington, DC, USA, Parking Meter Program Using a Lean Six Sigma Improvement Process</title>
      <link>https://trid.trb.org/View/1323905</link>
      <description><![CDATA[The District Department of Transportation (DDOT) is responsible for maintaining and  operating more than 18,000 metered on-street spaces in Washington, DC, USA. The program went  through significant changes in 2009 and 2010 including two rate adjustments, reintroduction of  meter enforcement on Saturdays, and extending hours of meter operation to 10:00 p.m. in high-demand areas. These changes caused operational problems for the department and frustration for the  customers. This paper describes how DDOT applied Lean Six Sigma (LSS) processes and techniques  to dramatically transform its on-street parking meter program. The paper introduces the concept  of LSS and discusses how some of the analytical techniques and concepts were applied. Techniques  such as root cause analysis, process capability, mean testing, Pareto analysis, and process mapping  were used to identify fundamental problems with the program and assets. Once the problems were  identified, DDOT quickly developed a strategic vision for the future and aggressively implemented the  vision. Applying LSS techniques has reaped significant rewards for DDOT within a very short period  of time. These benefits include higher customer satisfaction through enhanced payment options, a  lower number of service requests, better system uptime, more proactive management of assets, better  executive visibility, and increased revenue. Washington, DC’s parking program is now recognized as  one of the most innovative, forward-thinking programs in the country. The success of applying LSS in  parking has encouraged DDOT to apply this concept in other program areas as well.]]></description>
      <pubDate>Fri, 26 Sep 2014 14:24:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1323905</guid>
    </item>
    <item>
      <title>Public Perception of Double Crossover Diamond Interchanges</title>
      <link>https://trid.trb.org/View/1323921</link>
      <description><![CDATA[A double crossover diamond (DCD) interchange (a.k.a. diverging diamond interchange)  is a new unconventional diamond-type interchange. The purpose of this interchange design is to  accommodate left-turning movements onto arterials and limited-access highways while eliminating  the need for a left turn bay and signal phase at the ramp terminals. During a large study sponsored  by the Federal Highway Administration, the research team examined how users perceived new DCD  interchanges using focus groups formed at three DCD sites with 20 total participants and attitudes  summarized from surveys conducted at two DCD sites with a total of 1,649 participants. The team  further explored the results of one of the surveys, comparing opinions expressed before and after  the installation of a DCD. The results from both the focus groups and surveys revealed that DCD  interchanges operated properly, but there is room for improvement in how these interchanges  might be more readily accepted by the public. In regards to general knowledge and comfort with  the interchange and safety (real or perceived), users generally thought the interchange was an  improvement over the existing facility. The most frequently reported issues are summarized for  further consideration in outreach, education, planning, or design. Specific changes could be made  in regards to the scope of the project to include adjacent interchanges, adjustments with signal  operations, and the inclusion of facilities to accommodate both bicyclist and pedestrian travel to  increase user satisfaction with DCD interchanges.]]></description>
      <pubDate>Fri, 26 Sep 2014 14:24:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1323921</guid>
    </item>
    <item>
      <title>A Methodology for Evaluating Centerline Markings in Temperate Climates</title>
      <link>https://trid.trb.org/View/1286993</link>
      <description><![CDATA[Highway pavement markings constitute a vital component in roadway transportation systems and provide crucial visual cues for drivers to follow the road. In 2008, the South Carolina Department of Transportation initiated a study to evaluate pavement markings on primary and secondary roads. This paper discusses development of a methodology for estimating and comparing lifecycles of yellow centerline pavement markings based on retroreflectivity levels. The methodology was developed using 3 years’ worth of data from more than 100 test sites located throughout South Carolina. The paper provides an overview of data collection and analysis methods employed in model development. Findings from this research should be of interest to other states and jurisdictions located in temperate climates similar to that of South Carolina.]]></description>
      <pubDate>Mon, 27 Jan 2014 10:45:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1286993</guid>
    </item>
    <item>
      <title>Reducing Conflicts between Pedestrians and Left-Turning Vehicles</title>
      <link>https://trid.trb.org/View/1286994</link>
      <description><![CDATA[Pedestrian safety is a growing concern at signalized intersections. Pedestrian-vehicle crashes tend to be less frequent but more severe than crashes involving only vehicles. The cost of a pedestrian-vehicle crash has been estimated at four times that of a vehicle-vehicle crash on a willingness-to-pay basis. To address pedestrian safety concerns at signalized intersections, treatments can be used to separate pedestrians and vehicles in time and space, improve pedestrian compliance with signal control, and remind drivers and pedestrians to be aware of each other’s presence. The effectiveness of pedestrian safety treatments is often assessed by monitoring trends in pedestrian-vehicle conflicts (indicated by evasive movements by drivers or pedestrians) and pedestrian compliance (indicated by pedestrians’ response to the WALK interval). Crash data can be used, but the relative rarity of pedestrian-vehicle crashes must be overcome by observing a large number of sites or over a long period. Conflicts are more frequent and thus can provide more timely safety evaluation than crash-based analysis. Four pedestrian safety treatments were evaluated using before-after studies. These treatments included adding a leading protected left-turn phase, implementing split phasing, implementing pedestrian recalls, and increasing the WALK interval duration. The first three treatments were found to reduce pedestrian-vehicle conflict rates. The treatments had mixed effects on pedestrian compliance.]]></description>
      <pubDate>Mon, 27 Jan 2014 10:45:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1286994</guid>
    </item>
    <item>
      <title>Use of Auxiliary Lanes at Isolated Highway 1 On-Ramp Junctions</title>
      <link>https://trid.trb.org/View/1286992</link>
      <description><![CDATA[This paper uses the 2010 Highway Capacity Manual’s analysis procedure to investigate the operational benefits of having auxiliary lanes at isolated highway on-ramp junctions. The study scenarios cover only one-lane on-ramps but with different numbers of lanes on the highway, different highway and ramp volumes, and different lengths of auxiliary lanes. The first part of the study quantifies the reduction in density and improvement in the level of service in the merge influence area before and after the addition of auxiliary lanes of different lengths. The second part of the study uses level-of-service-improvement criteria to identify the design scenarios in which auxiliary lanes should be incorporated in on-ramp junctions. Tables of minimum lengths of auxiliary lanes provide guidance for design engineers. The outcomes of this research provide quantitative justifications for engineers to add auxiliary lanes at on-ramp junctions and suggest minimum lengths for these lanes.]]></description>
      <pubDate>Mon, 27 Jan 2014 10:45:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1286992</guid>
    </item>
    <item>
      <title>Comparison of the Retroflective Durability of Rumble Stripes and Painted Lines</title>
      <link>https://trid.trb.org/View/1251119</link>
      <description><![CDATA[Rumble strips have been used for many years to provide vibratory feedback to drivers who are drifting out of their lanes. Often these strips were placed next to the marked lines; recently agencies have started combining the markings with the strips. These painted rumble strips - known as "rumble stripes" - are emerging as centerline and edge line treatments that can alert drivers who are beginning to move outside the marked lane. A collateral benefit of painting edge lines in the rumble strip is the potential to increase the retroreflective durability of the lines, particularly in areas that have substantial snowplowing operations in the winter.]]></description>
      <pubDate>Tue, 28 May 2013 09:36:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1251119</guid>
    </item>
    <item>
      <title>Using GPS to Locate No-Passing Zones on Straight Sections of Two-Lane Highways</title>
      <link>https://trid.trb.org/View/1251109</link>
      <description><![CDATA[This article describes a method of using global positioning system (GPS) coordinates to identify the location of no-passing zones in vertical curves. It details a new application of a mathematical technique to smooth GPS data and obtain a geometric model of the roadway, then describes an analytical algorithm for analyzing the availability of sight distance along the vertical profiles of two-lane highways. The algorithm is incorporated into a computer model that can use GPS data as the input and produce a more efficient, accurate, and safe method of locating no-passing zones compared with the current field measurement methods, which place crews on highways in the presence of moving traffic. The automated system processes GPS coordinates and converts them into easting and northing values, smooths GPS data, and evaluates road profiles for possible sight restrictions, which indicate where no-passing zones should be located according to the vertical alignment. In a comparison of these results with existing pavement markings, the model shows potential for evaluating available sight distance and locating no-passing zones.]]></description>
      <pubDate>Tue, 28 May 2013 09:36:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1251109</guid>
    </item>
    <item>
      <title>Safety Impacts of Signing Delineation for Horizontal Curves on Rural Two-Lane Roads</title>
      <link>https://trid.trb.org/View/1251120</link>
      <description><![CDATA[As part of its strategic highway safety effort, the Federal Highway Administration (FHWA) organized a pooled fund study of 26 states to evaluate low-cost safety strategies. One of the strategies chosen to be evaluated for this study was improving curve delineation. Geometric, traffic and crash data were obtained at 89 treated curves in Connecticut, USA, and 139 treated curves in Washington, USA, to determine the safety effectiveness of improved curve signing. Treatments varied by site and included new chevrons, horizontal arrows, advance warning signs, and improvement of existing signs using fluorescent yellow sheeting. All sites were on two-lane rural roads. To account for potential selection bias and regression-to-the-mean, an empirical Bayes before-after analysis was conducted.]]></description>
      <pubDate>Tue, 28 May 2013 09:36:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1251120</guid>
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