bluuebunny/crossref_metadata_2025 huggingface dataset:
Echo Sign: J.M. Synge and Naturalist Theatricality
Authors: Bogucki Michael
Published: December 2010

The Irish playwright J.M. Synge's earliest dramatic experiments and first produced play, The Shadow of the Glen (1903), blend a critique of theatricality with a Darwinian picture of language and emotion. Focusing on symptoms of linguistic disorders that Darwin calls “the echo sign,” this article explores how Synge accounts for the emergence of theatrical affects as a telling condition of modern life in rural Ireland. In Shadow, the rapid development of any gesture, any affect, or any talk into a definitive sign of the presence or absence of love is a comical premise, but this quality – of being fated to expression – would become the devastating centre of Synge's later, longer work.
Une version canadienne française du Lower Extremity Functional Scale (LEFS) : L'Échelle fonctionnelle des membres inférieurs (ÉFMI), partie I
Authors: René Frédéric , Casimiro Lynn , Tremblay Manon , Brosseau Lucie , Lefebvre Annabelle , Beaudouin Martine , Belliveau Véronik , Bergeron Louis-Philippe
Published: December 2010

RÉSUMÉ

Introduction : Le Rehabilitation Network of Ottawa-Carleton (RENOC) recommande à ses établissements de santé d'utiliser le Lower Extremity Functional Scale (LEFS). Puisque le RENOC dessert une clientèle anglophone et francophone, il s'imposait de traduire le LEFS pour l'évaluation de la clientèle francophone.

But : Produire une traduction canadienne-française du LEFS sous l'appellation proposée « Échelle fonctionnelle des membres inférieurs (ÉFMI) » et examiner la validité de son contenu.

Méthodologie : Nous avons utilisé une approche modifiée de la méthodologie de validation transculturelle de questionnaires de Vallerand (1989). Une traduction renversée parallèle du LEFS a d'abord été complétée. Ensuite, un comité d'experts a examiné les deux versions préliminaires et a créé la première version expérimentale de l'ÉFMI. Cette version fut évaluée par un deuxième comité d'experts, dont les commentaires menèrent à une deuxième version expérimentale. Finalement, 35 professionnels de la réadaptation évaluèrent la version expérimentale de l'ÉFMI sur une échelle d'ambiguïté et proposèrent les modifications finales.

Résultats : Pour les différents énoncés de la version finale de l'ÉFMI, les moyennes sur l'échelle d'ambiguïté démontrent un niveau d'ambiguïté relativement faible puisqu'elles varient entre 1 et 2.54.

Conclusion : Les quatre étapes rigoureuses du processus ont permis de produire une version valide du LEFS en français.
Pavement Rehabilitation Project Ranking Approach Using Probabilistic Long-Term Performance Indicators
Authors: Abaza Khaled A. , Murad Maher M.
Published: December 2010

A probabilistic performance-based approach for generating a priority ranking of pavement rehabilitation project candidates is presented. The deployed probabilistic approach uses a discrete-time Markovian model to predict pavement conditions at the network level. The expected future distress rating associated with a particular pavement project is determined as the mean of a compound uniform probability density function derived from the corresponding future state probabilities. The expected future distress ratings for a particular pavement project are then used to construct the corresponding performance curve. The generated performance curves form the basis for developing an effective mechanism for prioritizing potential rehabilitation projects. A priority ranking system is presented with two alternatives. The first priority ranking alternative requires a fixed analysis period wherein project candidates are evaluated by using three different long-term performance indicators derived from the corresponding performance curves. The deployed performance indicators include the area under the performance curve, the average distress rating, and the terminal distress rating. The second priority ranking alternative requires a fixed terminal distress rating for the pavement network under consideration. The time required for each project to reach the terminal distress rating is determined as the rehabilitation scheduling time, which is used to establish project priority ranking. Pavement rehabilitation project candidates are then scheduled according to their priority rankings and available budget. The developed probabilistic approach is demonstrated by considering a project sample from the two-lane highway system in Ohio.
Validation and Implementation of Ontario, Canada, Network-Level Distress Guidelines and Condition Rating
Authors: Chamorro Alondra , Tighe Susan L. , Li Ningyuan , Kazmierowski Tom
Published: December 2010

The Centre for Pavement and Transportation Technology at the University of Waterloo and the Ministry of Transportation of Ontario (MTO) have been studying for the past 4 years the suitability of applying automated technologies for network-level evaluations in the province. Three projects have been developed for this purpose. The main results of these studies were a better understanding of available digital technologies, evaluation of the performance of semiautomated and automated technologies, development of new guidelines for pavement distress collection at the network level, design of an adjusted distress manifestation index, and recommendations for the use of semiautomated and automated digital technologies at the network level. The objective of this paper is to present the findings of the third and last phase of the project, Validation and Implementation of MTO Network Level Automated–Semiautomated Pavement Distress Guidelines and Condition Rating Methodology. The scope of the study was to validate and implement in the field MTO network-level distress guidelines and a distress manifestation index for network-level evaluations (DMINL), considering the use of automated technologies. A complete statistical analysis of data collected in the field through manual evaluations and semiautomated and automated technologies is presented. The performance of currently available technologies using network-level distress guidelines was assessed. Finally, from the field validation, distress guidelines were adjusted accordingly and DMINL equations were recalibrated.
Index of Foreign Object Damage in Airfield Pavement Management
Authors: Li Xue , Keegan Katherine , Yazdani Alan
Published: December 2010

Control of foreign object damage (FOD) on airfield pavements is critical to the safety of aircraft operations. An index was developed to identify the FOD potential caused by deterioration of airfield pavements and was incorporated in airport pavement management systems. However, current pavement maintenance policies are determined mainly by the pavement condition index (PCI). This study investigates if the current practice of PCI-based pavement maintenance plans is able to address the maintenance required to reduce and contain FOD. This study includes 27.1 million square feet of airfield pavement at a commercial and a general aviation airport. It was observed that, in general, PCI-based pavement maintenance plans can accommodate the maintenance requirements triggered by FOD-related distresses. An innovative normalized PCI–FOD system was developed to identify efficiently sections that may be overlooked. It was determined that some pavement sections may require maintenance on the basis of FOD potential only although they have acceptable PCI values.
Comparison of Flexible Pavement Distresses Monitored by North Carolina Department of Transportation and Long-Term Pavement Performance Program
Authors: Corley-Lay Judith , Jadoun Fadi M. , Mastin Jeffery Neil , Kim Y. Richard
Published: December 2010

The Long-Term Pavement Performance (LTPP) program has collected pavement distresses for general pavement study (GPS) sites throughout the country. These sites were used in the initial calibration of the Mechanistic–Empirical Pavement Design Guide, so it is important for states to compare their distress identification procedures and results with the LTPP distresses as part of the local calibration process. North Carolina has 24 GPS sites, of which four are concrete, one went out of service very early, and the remainder are flexible pavements. This paper focuses on the flexible pavement distresses. The GPS sites are 500-ft sections of much longer roadways. The LTPP distress data were extracted for the North Carolina Department of Transportation (NCDOT) GPS sites. Corresponding locations and their distress histories were pulled from the NCDOT pavement management system. In addition, rut depth measurements taken by high-speed profilometer were obtained for many of the sections for comparison with LTPP rut depth measurements. As might be expected, the LTPP walking survey revealed higher amounts of distress than the NCDOT windshield survey. Alligator cracking is the major distress for NCDOT pavements, and a roughly two-to-one relationship was found between alligator cracking by LTPP compared to NCDOT. Rut depths measured by LTPP were also found to be larger than those measured by high-speed profilometer, but in either measure, rut depths measured for NCDOT sections were low (less than 10 mm for all sites).
Evaluation Method for Transverse Cracking in Asphalt Pavements on Freeways
Authors: Zhou Lan , Ni Fujian , Zhao Yanjing
Published: December 2010

Transverse cracking is one of the major distresses in asphalt pavements. The objective of this research is to establish an effective evaluation method for transverse cracking in asphalt pavements on China's freeways. Two single indicators are presented that assess the key properties of transverse cracking: transverse crack spacing and transverse crack width ratio. The transverse crack condition index (TCCI) is then developed as a comprehensive evaluation index of transverse cracking in this study. The feasibility of this evaluating method was checked with the analysis of field detection data from Wu Xuan freeway in Anhui Province and two other freeways in Jiangsu Province, China. Through the introduction of an expert evaluation, the TCCI was converted to a scale from 0 to 100, and the threshold value was confirmed. Furthermore, the corresponding maintenance treatment method was determined according to the different transverse cracking condition levels. The results showed that the TCCI can make a good assessment of transverse cracking in freeway asphalt pavements. The index value can be correlated with the actual condition of the pavement. Therefore, a scientific and rational evaluating method is established for transverse cracking on freeways.
Confidence Level and Efficient Sampling Size of Roughness Measurements for Pavement Management in Maryland
Authors: Shirazi Hamid , Ayres Manuel , Speir Rich , Song Wenbing , Hall Geoff
Published: December 2010

The international roughness index (IRI) is the primary index of the Maryland pavement management system and is the data source for performance trend analysis, budget allocation, and project selection. The Maryland State Highway Administration (MDSHA) makes a significant investment to collect, process, analyze, and store IRI data every year over the entire network of the roads. Such reliance on IRI data and investment instigated the investigation of the confidence level embedded in the data and of devising possible sampling scenarios. To evaluate the confidence level, repeatability errors of the measurements were assessed. IRI data were repeatedly collected over a designated test loop under normal operating conditions to mimic network-level data collection. Sampling scenarios were devised using the Monte Carlo method for network IRI data collected in 2008. The network was stratified on the basis of functional classifications. Sampling errors in estimating the percentage of the roads in each of five IRI categories established by MDSHA were evaluated. The results indicated that the repeatability error of the measurements was less than 7%. The sampling results indicated that the state may survey a third of the network each year and expect estimation errors of less than 0.5% for all IRI categories. As such, MDSHA would not incur a considerable sacrifice in the confidence of network condition evaluation.
Development of a Global Positioning System–Based Vehicle Tracking System for the Minnesota Road Research Facility
Authors: Burnham Thomas , Vasudevan Madhavan , Tewfik Ahmed
Published: December 2010

One of the more important tasks in operating a pavement research test track is tracking the location of individual vehicles during load response testing. The location of a vehicle's tires profoundly affects values obtained from embedded pavement load response sensors. To improve the efficiency of load response testing both in the field and during analysis, a Global Positioning System-based vehicle tracking system (VTS) was developed and tested at the Minnesota Road Research Facility (MnROAD). The VTS demonstrated its capability of tracking vehicle motion with an accuracy of ± 1 in. (2.5 cm) at speeds up to 45 mph (70 km/h). These results matched or exceeded the accuracy obtained with a high-definition video camera previously used for tracking vehicle position at MnROAD. Additional field trials were conducted in greater Minnesota to determine the operational area of the VTS. Overall, the VTS received real-time kinematic signal correction in nearly 80% of the tested areas. The capabilities of the VTS spawned the development of the wireless triggering system. Through wireless triggering of data acquisition, the load test process can be greatly simplified. Although preliminary testing confirmed it as proof of concept, hardware issues dictate that additional development is necessary.
Improving the Safety of Mobile Lane Closures
Authors: Steele Douglas A. , Vavrik William R.
Published: December 2010

Mobile lane closures, which are increasingly used, are a potentially hazardous traffic control procedure for highway maintenance and operations activities. To improve the safety of workers and motorists, Applied Research Associates, Inc., studied driver behavior around full-scale field tests of mobile lane closures. Tests were conducted over a range of traffic, roadway, and driver conditions, and effects of various traffic control components (including truck number, spacing, and configuration; sign messages; and police presence) were evaluated. This report summarizes Phase I results and important findings regarding the behavior of motorists around mobile lane closures. Phase II research is ongoing and will recommend revisions to existing traffic control standards.
Devices to Implement Short-Term Speed Limits in Texas Work Zones
Authors: Theiss LuAnn , Finley Melisa D. , Trout Nada D.
Published: December 2010

In Texas, speed limits for short-term (less than 12 consecutive h) work zones are used when workers or equipment are not behind a concrete barrier, work activity is within 15 ft of the pavement edge, or work is actually occurring on the pavement. In these situations, speed limit signs for short-term work zones should be posted and visible to the motorists only when work activity is present and covered or removed when no work activity is present. Covering or removing signs can be a tedious task to complete daily or weekly. In addition, this task may interfere with normal traffic flow and expose workers to traffic hazards. Some contractors choose not to cover or remove signs; others simply forget: thus speed limits for short-term regulatory work zones extend into time periods with no apparent need for a speed limit reduction. New sign technologies may simplify the implementation process speed limits for short-term work zones and could enhance the use of such speed limits in general. However, such technologies have not been used extensively for speed limits in work zones in Texas. Thus, researchers at the Texas Transportation Institute conducted field studies to determine the operational effectiveness of electronic speed limit signs and flexible roll-up speed limit for work zones signs. The researchers recommended the use of both types of signs.
Simulation Models for Assessment of the Impacts of Strategies for Highway Work Zones
Authors: Collura John , Heaslip Kevin P. , Moriarty Kevin , Wu Francis , Khanta Raju , Berthaume Andrew
Published: December 2010

As the National Highway System reaches the end of its serviceable life, transportation agencies increasingly need to focus on the preservation, rehabilitation, and maintenance of these roads. In light of significant increases in work zone activity, transportation officials and contractors are challenged to find ways to reduce the negative impacts on driver mobility. The key to addressing this challenge is to recognize potential impacts well in advance. One major tool used for this purpose is computer simulation. Many simulation models exist, some designed specifically for work zone analysis, including QUEWZ, QuickZone, CORSIM, and CA4PRS. This purpose of this paper is to present case studies that illustrate and evaluate these models for ease of use, data requirements, and ability to simulate and assess work zone strategies, shedding light on the relative reliability and accuracy of these simulation models as well as their user-friendliness and data requirements. This paper compares simulation results with actual work zone conditions in eight locations across New England. The results of this evaluation will be of interest to state and local transportation engineers responsible for planning and designing work zone strategies. This research has shown that some simulation models provide a low-risk, low-cost environment in which to test and analyze a variety of work zone alternatives. For example, QUEWZ and QuickZone were able to provide reasonable order of magnitude queue length estimates on Interstate highways that were comparable with observations made in the field. In addition, such estimates required few data, including hourly volume and roadway geometry information.
Estimating Operational Impacts of Freeway Work Zones on Extended Facilities
Authors: Schroeder Bastian J. , Rouphail Nagui M.
Published: December 2010

This paper presents an approach to estimating the operational impacts of freeway work zones. The focus is on significant work zones on freeway corridors as defined by FHWA. The methodology is based on deterministic freeway capacity concepts described in the Highway Capacity Manual and allows the analyst to test impacts of a range of work zone configurations in an extended time–space domain. The focus on extended facilities refers to the analysis of multiple segments of various types, including basic freeway, ramp, and weaving segments. The cost-effective and time-efficient analysis approach can model effects of work zones such as lane closures, lower speed limits, capacity reduction, and the implicit effects of traffic diversion, peak reduction, and other intelligent transportation system strategies. Performance measures include total delay, queuing impacts, average running speed, and the potential to estimate user cost. The methodology focuses on a corridor-based analysis of work zones on freeways. It is not appropriate for network analysis, for long corridors, for signalized arterials, or for cases in which congestion on the arterial network significantly affects freeway operations. In these applications, a simulation-based analysis is more appropriate. However, the methodology presented in this paper is more cost-effective and less data intensive than simulation analysis and can readily be calibrated with local or regional data. This is a key advantage in challenging economic times, when agencies struggle to balance a constrained budget with the need to analyze multiple construction projects within their jurisdiction.
Motorist Understanding of Alternative Displays for Speed Limits in Work Zones
Authors: Trout Nada D. , Finley Melisa D. , Ullman Gerald L.
Published: December 2010

In Texas, speed limits for short-term work zones are reduced speed limits that are posted only when work activity is present. When work activity is not present, the reduced speed limit signs are to be removed or covered; the legal speed limit for that segment reverts to the normal zone speed limit. The major challenge of speed limits for short-term work zones is the daily process of installing and removing, or uncovering and covering, signs. In this study, researchers conducted a laptop-based laboratory survey to determine (a) motorists' understanding and opinions of alternative short-term signs for speed limits in work zones and the enforceability of limits, (b) the success of the orange or white light-emitting diode (LED) color used on electronic speed limit (ESL) signs and portable changeable message signs (PCMSs) in indicating to motorists that they were advisory or regulatory signs, and (c) motorists' preference for short-term speed limit displays. The four categories of signs included in the survey were static work zone signs, ESL signs, speed limits displayed on PCMSs, and “Your Speed” signs (distracters). On the basis of the results obtained from this survey, researchers recommend the use of ESL signs and flexible roll-up signs for speed limits in static work zones for displaying speed limits in short-term work zones. To ensure that the speed limit displayed on ESL signs is considered a regulatory speed limit, the changeable display should be composed of white LEDs.
Quantitative versus Qualitative Assessment of Pavement Marking Visibility
Authors: Pike Adam M. , Kuchangi Shamanth P. , Benz Robert J.
Published: December 2010

Many state departments of transportation (DOTs) often use a subjective evaluation program to assess the condition of their roadway assets. Because pavement markings are typically only a small part of these assessment programs and because visual assessment is subjective, the ratings may not always be accurate in identifying roadways with inadequate markings. This research sought to evaluate the accuracy of visual assessments of pavement markings. The Texas Transportation Institute conducted two separate nighttime evaluations as part of a Texas DOT research project. The first evaluation was conducted on open roads, and the second was conducted on a closed experimental course. Subjective rating data were collected on pavement markings by several DOT evaluators. To analyze the data, researchers compared retroreflectivity measurements with subjective ratings of the pavement markings. For the first night study, the average subjective rating of each marking compared with the measured retroreflectivity resulted in a logarithmic R2 value of .818. The second night study resulted in a logarithmic R2 value of .821 before training and .809 after training. The data were also evaluated by marking color and evaluator experience level. Researchers found that average subjective ratings showed acceptable correlation with retroreflectivity measurements, but ratings could show large variations between individuals. The researchers recommend that subjective assessment be considered a viable option for evaluating pavement markings. They also recommend that for any assessment the evaluator be well trained or multiple evaluators be utilized, with reported ratings averaged to provide reliable results.
Repeatability of Mobile Retroreflectometer Unit for Measurement of Pavement Markings
Authors: Holzschuher Charles , Choubane Bouzid , Fletcher James , Sevearance Joshua , Lee Hyung Suk
Published: December 2010

The mobile retroreflectometer unit (MRU) has been recognized by highway agencies as an appealing alternative to handheld retroreflectometers because of its improved safety and efficiency. Over the past 4 years, the Florida Department of Transportation has been researching the use of the MRU for evaluating pavement markings continuously and reliably at traffic speeds. Because the stripe surface is nonuniform and the measurement process relies on the operator-driven instrument device, there is some uncertainty in evaluating pavement markings with the MRU. As part of the broader effort for MRU implementation, this research assesses MRU precision in repeatability for pavement marking retroreflectivity. Six designated sections of roadway were selected at random for testing on various pavement surfaces and pavement stripes (paint and thermoplastic). Retroreflectivity data were collected only on the white edge lines of the test sites. The survey limits were selected so that the effect of nonretroreflective-related variables, such as breaks in the pavement markings, inclines, declines, and curves in the roadway, could be minimized. The data were analyzed to determine the pavement marking characteristics at each test location for retroreflectivity at 80 km/h (50 mph) using the reduced 30-m geometry standard. Results indicated that the retroreflectance values from two properly conducted tests using the same MRU on the same pavement marking should not differ by more than 20.1 mcd/m2/lux or 6.7% at a 95% confidence level for retroreflectivity values ranging between 200 and 450 mcd/m2/lux. This paper presents a description of the testing program, the data collection effort, and the subsequent analyses and findings.
Diagnosing Road Weather Conditions with Vehicle Probe Data
Authors: Chapman Michael , Drobot Sheldon , Jensen Tara , Johansen Christian , Mahoney William , Pisano Paul , McKeever Benjamin
Published: December 2010

Over the past 2 years, the U.S. Department of Transportation RITA funded an IntelliDrive vehicle probe data collection test bed in the northwest Detroit, Michigan, area. The purpose of the test bed was to provide the infrastructure for both public and private organizations to collect, process, and generate a robust observation data set for multiple purposes (e.g., crash avoidance, automated toll services, weather diagnostics). During April 2009, a weather-specific field study was performed over an 11-day period. The resulting data set was processed by a vehicle data translator (VDT), which parsed, quality controlled, and combined these data (with ancillary weather data) in the generation of road weather-specific algorithms. This paper briefly describes the VDT concept and then examines the accuracy of the quality-controlled temperature and pressure data (for several different stratifications) collected from 11 specially equipped vehicles operated during the study time period. Results show that the vehicles accurately measure the temperature (compared with a nearby fixed weather station, KDTW), but are not as accurate at measuring the barometric pressure. In addition, stratification by speed, vehicle type, time of day, and occurrence of precipitation do not affect the accuracy of the temperature and barometric pressure measurements.
Analysis of Impact of Adverse Weather on Freeway Free-Flow Speed in Spain
Authors: Camacho Francisco Javier , García Alfredo , Belda Enrique
Published: December 2010

Weather conditions affect traffic flow characteristics, including speed and capacity. Several studies have stated that rain, snow, wind speed, and visibility loss cause reductions in speed and capacity. Understanding these relationships is important to managing the traffic flow appropriately. This paper presents new research that evaluates the free-flow speed reduction caused by inclement weather conditions, including rain, snow, wind speed, and visibility loss. Fifteen freeway locations in northwestern Spain were selected for the study. Data were collected in 15-min intervals by weather and traffic stations for almost 3 years, from 2006 to 2008. Individual correlations between the weather and traffic variables were examined to select the most important weather variables and to identify speed trends and thresholds. All climate conditions were divided into four groups: no precipitation and temperatures above 0°C, no precipitation and temperatures below 0°C, rain, and snow conditions. A multiple nonlinear regression analysis was performed with the final variables. Results showed that rain and snow both caused a reduction in speed, with a more dramatic reduction during snow conditions. Wind speed over 8 m/s affected traffic speed, while the effect of visibility loss presented a logarithmic form. It was also determined that the location caused the variables to affect the speed differently, so further research should utilize a greater number of sites.
Small Unmanned Aircraft Evaluated for Avalanche Control
Authors: McCormack Edward , Stimberis John
Published: December 2010

The Washington State Department of Transportation's (DOT) snow avalanche control program reduces winter roadway closure times and hazards to motorists. The University of Washington and the Washington State DOT evaluated small unmanned aircraft systems (UASs) as a tool to enhance this program. Because of military investment, UAS technology has dropped in cost as it has become increasingly capable and easier to operate. Commercially available UASs, which fly autonomously, can be operated off a roadway and can collect low-cost, real-time aerial imagery while also carrying payloads. This project conducted a series of test flights involving both fixed- and rotary-wing (helicopter) UASs over a roadway in mountainous terrain. The flights demonstrated that UASs can conduct snowpack and terrain surveillance and can accurately drop explosive charges such as those used to trigger controlled avalanches. The rotary-wing UAS was particularly usable because of its ability to hover, which provided a stable camera platform, and because it required minimal area to land. The reliability of UASs is a concern, and their capabilities may be challenged by mountainous terrain and weather. This problem may be reduced as UASs become either less expensive and more expendable or more reliable and all-weather capable. A major barrier to use of UASs is the need to obtain approval to fly from FAA, a process that can be time-consuming and restrictive. FAA is currently updating its plans to integrate UASs into the national airspace, and a number of technology-based solutions are being considered.
Costs and Benefits of Tools to Maintain Winter Roads
Authors: Fay Laura , Veneziano David A. , Ye Zhirui , Williams Dan , Shi Xianming
Published: December 2010

Some of the most useful data available to winter road maintenance managers and others charged with decision making are the costs, benefits, and effectiveness associated with winter maintenance of practices, equipment, and operations. However, significant effort may be required to track down this information, and access to published reports and papers is not guaranteed. This paper presents recent research results to assist practitioners in understanding the current state of the practice related to specific items. The information presented here focuses on the top 10 winter maintenance practices, equipment, and procedures as identified by practitioners, including anti-icing, deicing, front and underbody blades, automatic vehicle location and Global Positioning System technologies, pavement temperature sensors, road weather information system (RWIS), maintenance decision support system, carbide blades, air temperature sensors, and zero velocity spreaders. A review of the literature pertaining to these items indicated that, depending on the item of interest, significant data gaps might exist. This was less true for items such as RWIS and more true of items such as temperature sensors and material placement systems. Overall, quantified costs and benefits related to many items are still needed. In addition, further investigation is necessary to quantify the dollar values of costs and benefits associated with many items considered intangible at present. The determination of the values of such costs and benefits would assist in the conduct of cost–benefit studies and decision making.
Measurement and Comparison of Acceleration and Deceleration Zones at Traffic Control Intersections
Authors: Boonsiripant Saroch , Hunter Michael , Dixon Karen , Rodgers Michael O.
Published: December 2010

Acceleration and deceleration characteristics are basic driving behaviors that influence signal control and road geometry. Most previous studies focused on acceleration and deceleration rates under ideal conditions, i.e., on characteristics of lead vehicles, which might not adequately reflect the full spectrum of traffic operations. This paper presents a methodology for determining acceleration and deceleration rates and zone lengths for vehicles approaching and leaving intersections under likely uncongested traffic conditions, regardless of queue position. These characteristics are derived from speed profiles gained from vehicles equipped with Global Positioning System (GPS) instrumentation. With the speed profiles obtained from GPS-equipped vehicles, a series of data-processing algorithms is developed to measure the acceleration and deceleration behavior of vehicles approaching and departing an intersection. Acceleration and deceleration rates and zone lengths are estimated for several road categories. These zone lengths are compared with recommended values from AASHTO's A Policy on Geometric Design of Highways and Streets (Green Book), in which it is seen that the zone lengths under light traffic conditions are longer than the Green Book's values. In addition, determined acceleration and deceleration rates and zone lengths are found to depend on the underlying assumptions and calculation methods of the analysis.
Evaluation of Traditional and Nontraditional Interchange Treatments to Preserve Service Life of Narrow Over-and Underpass Roadways
Authors: Click Steven M. , Berry Chris , Mahendran Ashok
Published: December 2010

This paper presents key findings from an evaluation of the potential of traditional and nontraditional interchange treatments to postpone or eliminate the need for overpass or underpass widening. The study compares the relative performance of five traditional and five nontraditional interchange treatments at two common sites. The treatments included traditional widening, single-point urban interchange, tight urban diamond, Texas three-phase (TX-3), Texas four-phase (TX-4), tight urban diamond with reversing lanes, double roundabout, diverging diamond, median U-turn, and superstreet. Although the performance of each treatment will always vary with site-specific geometric and volume characteristics, some general trends were apparent across sites. The TX-3 and TX-4 treatments were found to be excellent short- to medium-term performers, especially considering their low cost for implementation. The tight urban diamond with reversing lanes and the diverging diamond treatments were found to be reasonable medium- to long-term performers, although each was better suited to particular traffic patterns. The traditional widening and single-point urban interchange treatments were the best long-term performers, with the single-point urban interchange providing the best performance overall.
Performance Analysis of Parallel Flow Intersection and Displaced Left-Turn Intersection Designs
Authors: Dhatrak Amit , Edara Praveen , Bared Joe G.
Published: December 2010

The displaced left-turn (DLT) design, also known as the continuous flow intersection, has proved to be a superior alternative to the conventional intersection in terms of handling heavy volumes during peak periods. In locations where the availability of additional right-of-way and driveway access is not a major concern, the DLT design is a cost-effective and time-saving option compared with the expensive option of grade-separated interchanges. Recently, a new nontraditional intersection design called the parallel flow intersection (PFI) has been proposed. The PFI is also an at-grade design and operates with the same number of signal phases as a DLT. This research compares the operational performance of DLT and PFI designs based on the maximum through and left-turn movement throughputs for three different high-volume scenarios using traffic simulation. The results indicate that maximum throughput values of through movement in the PFI were very close to the values obtained for the DLT. The designs produced similar results, mainly because both operate as two-phase signals (at the main intersection) with equal green times for through movements. The left-turn movement throughputs in the PFI were found to be lower than those in the DLT. For two study cases, the DLT was able to process 180 and 80 more vehicles per hour per lane than the PFI. This is attributable to left-turning vehicles experiencing a greater number of stops, on average, in a PFI than they would in a DLT.
Safety Evaluation of Offset Improvements for Left-Turn Lanes
Authors: Persaud Bhagwant , Lyon Craig , Gross Frank , Eccles Kimberly
Published: December 2010

This study is a safety evaluation of offset improvements for left-turn lanes, a treatment intended to reduce the frequency of crashes by providing better visibility for drivers who are turning left. Geometric, traffic, and crash data were obtained for installations in Nebraska, Florida, and Wisconsin and for a number of untreated reference sites in each state. To account for potential selection bias and regression to the mean, an empirical Bayes before–after analysis was conducted. There was a large difference in observed effects in the three states, which may be explained, in part, by the variety of offset improvements applied. Florida and Nebraska employed pavement-marking adjustments or minor construction to improve the offset, but most improvements did not result in a positive offset. Wisconsin, conversely, reconfigured left-turn lanes through major construction projects and realized significant positive offsets. Wisconsin showed significant reductions in all crash types investigated (total reduction, 34%; injury, 36%; left turn, 38%; and rear end, 32%), while results in Florida and Nebraska showed little or no effect on total crashes. For Nebraska, however, a disaggregate analysis did reveal that the percentage reduction in crashes increases as the expected number of crashes increases. An economic analysis indicated that offset improvement through reconstruction is cost-effective at intersections with at least nine expected crashes per year and in which left-turn lanes are justified by traffic volume warrants.
Modeling and Evaluating Safety Impacts of Access Management Features in the Las Vegas, Nevada, Valley
Authors: Mauga Timur , Kaseko Mohamed
Published: December 2010

This paper presents results of a study that developed statistical models that relate access management (AM) features to traffic safety in midblock sections of street segments. The objective of the study was to evaluate and quantify the impact of the AM features on traffic crashes in the midblock sections. Models were calibrated for two main types of median treatments for street segments: raised medians (RM) and two-way left-turn lanes (TWLTL). Other AM features considered were signal spacing and the densities of driveways, median openings, and unsignalized crossroads. Separate models were developed to determine the impact on total crash rates and types and severity of crashes. The study results confirmed the intuitive expectation that these AM features do have a significant impact on safety. They show that the crash rate of segments with RM was lower by 23% as compared with segments with TWLTL. The results also showed that higher densities of driveways, unsignalized crossroads, and median openings resulted in higher crash rates and severity. For example, for segments with RM, each additional median opening per mile resulted in a 4.7% increase in the total crash rate. These results are compared with the results of previous similar studies. It is anticipated that the results of this study will assist local jurisdictions in the Las Vegas, Nevada, Valley in developing new AM policies and programs.
Making the Most of an Existing System through Access Management at Major Arterial Intersections
Authors: Schultz Grant G. , Allen Charles G. , Boschert Tim
Published: December 2010

The intersections of major arterials are designed to facilitate the conflicting movements of numerous vehicles in a manner that is both safe and efficient. Accesses located within the functional area of major arterial intersections complicate intersection activity because additional conflicts arise from ingressing and egressing movements at the accesses. This research analyzed the impact of accesses on crashes within the functional area of major arterials. The effects of access spacing within functional areas and access setback from intersections were addressed. The functional areas of 144 signalized major arterial intersections across the state of Utah were examined. A database was developed and contained the frequency, type, and severity of functional area crashes as well as the intersection and roadway characteristics within the functional area. Statistical analyses were conducted to determine the influence of accesses on crashes within the functional area of intersections. The statistical analyses showed that the existence of accesses within the functional area was correlated with increased crashes and crash severity costs. In particular, an increase in commercial access density was associated with increases in crash totals, crash rates, and rear-end crashes in intersection functional areas. The analyses also showed that study intersections meeting Utah Department of Transportation corner clearance standards exhibited fewer right-angle crashes and lower crash severity costs. Adherence to such standards improves safety and increases efficiency of the transportation network and thus aids jurisdictions throughout the nation in making the most of the existing infrastructure.
Effective Repair Grouting Methods and Materials for Filling Voids in External Posttensioned Tendons
Authors: Im Seok Been , Hurlebaus Stefan , Trejo David
Published: December 2010

Recent inspections of segmental posttensioned (PT) bridges reported the presence of large voids in ducts that contain PT strands. Corrosion of the strands was observed in these voids, which are believed to be a result of poor grouting. Corrosion of the PT strands can result in structural failure. Controversy exists on how best to protect PT tendons from corrosion; filling these voids with grout is one option. An optimized grouting procedure for repairing these voids is needed to protect the strands from corrosive environments. This research investigates three grouting methods for efficiently repairing the voids in PT duct systems: vacuum grouting (VG), pressure grouting (PG), and pressure–vacuum grouting (PVG). Each method is evaluated for filling capability, filling performance, and economic feasibility. Also, three prepackaged grouts for repair are assessed in this research to propose the most suitable material for repairing voids in the PT ducts. The results indicate that the PG and PVG methods are more constructible and likely to be more economical than the VG method. However, the PVG and VG methods seem to be more effective than the PG method in filling the voids. As a result of these tests, the PVG method is recommended for filling voids in tendons. The results also show that Classes C-1 and C-2 grouts have better filling capability than Class C-3 grout.
Shear Stiffness of Neoprene Bearing Pads under Long-Term Loads
Authors: Allen Damon T. , Cook Ronald A. , Ansley Marcus H.
Published: December 2010

This research evaluated the interaction between the shear modulus of steel-reinforced neoprene bearing pads and the shear strain rate. The following interactions related to variations in the shear modulus were investigated for pads with various shape factors: product approval strain rates versus short-term field strain rates, short-term field strain rates versus long-term field strain rates, reduction in shear modulus due to load cycles, and compressive stress. Forty-two tests were performed with test equipment designed to apply a shear strain at a variety of rates (50% shear strain at rates from 45 s to 90 days) while applying a sustained compressive load. Test results indicated that the shear modulus was reduced on average by 7% when tests were performed with the short-term field strain rates of 50% over 12 h instead of the product approval strain rates of 50% over 30 to 60 s, that there was essentially no reduction in shear modulus with long-term field loading rates of 50% over durations up to 90 days versus short-term field strain rates, that the shear moduli for pads that had never been load-cycled were approximately 12% higher than those of cycled pads, and that the effect of compressive stress agrees with previous work (i.e., the shear modulus decreases with increased compression particularly for bearings with low shape factors).
Convenient Method for On-Site Check of Single Steel I-Girder Stability during Erection
Authors: Zhao Qiuhong , Coffelt Sean Justin , Zou Tao , Yu Baolin , Burdette Edwin G. , Hastings John S.
Published: December 2010

The behavior of a single steel I-girder during erection is quite different from that of a girder under service: the girder during erection usually has limited or no lateral bracing along the span. Elastic lateral torsional buckling of the steel girder may occur if the girder span becomes too large. Rules of thumb have been used to check girder stability during erection by using the ratio of unbraced length L to compression flange width b; this is based on experience. For any longitudinally unstiffened girder section, formulas were developed on the basis of the current AASHTO load and resistance factor design code for the unique maximum L/b ratio. Parametric studies were then conducted to calculate Lmax and the (L/b)max ratio for a variety of girder sections that cover the range of practical design in order to identify dominant section parameters on the (L/b)max ratio as well as girder stability during erection and to develop simplified formulas for the upper and lower bounds of the (L/b)max ratio for all girder sections within the range of practical design. On the basis of the simplified formulas, an on-site check of single steel I-girder stability during erection could be conducted by checking the girder L/b ratio against the (L/b)max ratio for that given section or, even more easily, by checking the girder L/b ratio against the upper and lower bounds of the (L/b)max ratios for all girder sections.
Design and Application of Large-Scale Cast-Steel Joints for Special-Shape Bridges
Authors: Ding Jianming , Li Bingnan , Chen Juan , Chen Suhua
Published: December 2010

Because of their excellent structural performance, strong plasticity, and attractive appearance, cast-steel joints have gradually become a new type of joint for long-span steel-pipe modern architectural structures. Landscape bridges whose shapes are especially attractive have emerged; many have new and unique shapes and complicated structures. Some large-scale steel-pipe intersecting joints are designed in such structures. An innovative approach is presented: the use of cast-steel joints as two large-scale pipe intersecting joints of a special-shape tower in the design of a landscape cable-stayed bridge crossing over an expressway. The design methods for cast-steel joints that can be used on similar projects are also discussed.