bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimizing Opening of Portland Cement Concrete Pavements Using Integrated Maturity and Nondestructive Tests
Authors: Nazarian S. , Yuan D. , Medichetti A.
Published: April 2007

The seismic testing technique was combined with the maturity concept to monitor and predict the strength gain of portland cement concrete. In this process, the dynamic modulus of elasticity of a given mixture, obtained from its stress wave velocity, can be related to the strength parameters and static modulus of the mixture by using the same specimens used in the calibration process commonly carried out for maturity tests. When these relationships are combined with the maturity parameters, the predictive power is significantly improved. In this investigation, laboratory tests with molded specimens and cores were carried out by the simplified free–free resonant column method, and field tests of concrete slabs were performed with a handheld device called the portable seismic pavement analyzer. On the basis of the results of these experiments, relationships between the dynamic modulus and the strength parameters as well as the maturity are proposed. The technique was shown to be a rapid, simple, and economical means for optimization of concrete mix design, quality control–quality assurance of concrete construction, and determination of the time required before a repaired or newly constructed structure is ready for use.
Statistical Quality Control and Quality Assurance Evaluation of Structural and Paving Concrete
Authors: Diwan Ravinder M. , Shah Shashikant , Eggers John
Published: April 2007

The variability associated with the production, construction, and testing of structural and paving concrete is discussed. Data from more than 900 projects constructed from 1992 through 1999 representing more than 25,000 lots were evaluated. The data were collected from the Louisiana Department of Transportation and Development’s (DOTD’s) computerized Material Test Data Reporting System. The analysis indicated that ( a) overall price reductions were less than 0.2% for structural concrete and about 0.5% for paving concrete, ( b) the thickness of concrete cores is the major contributor to the overall reduction in the price of paving concrete, ( c) there was good control in the production and testing of structural concrete, and ( d) there was an increase in the nonuniformity of paving concrete acceptance criteria. Recommendations include a need to maintain better control of the variability of paving concrete through the application of control charts or unknown variability in the specification types and a need for continued evaluation for monitoring the overall quality control and quality assurance program of the DOTD.
Simplified Analysis of Heat-Curved Steel Girders
Authors: Gergess Antoine N. , Sen Rajan
Published: April 2007

Heat curving is commonly used in the fabrication of curved structural steel bridge girders. A two-dimensional superposition analysis known as the Duhamel Analogy was used for numerical modeling in the development of the AASHTO code provisions. This iterative analysis can take into consideration multiple heating–cooling cycles, initial residual stresses, temperature-dependent material properties, and the nonlinear temperature distribution across the girder cross section. A simplified analysis based on the Duhamel Analogy that can be carried out by using hand calculations is described. The curvatures obtained by this method are within 15% of the measured curvatures, which are very comparable to the results obtained by using the Duhamel Analogy or the three-dimensional, nonlinear, finite element solution. The background, basis, and steps required for the proposed analysis are described; and an illustrative numerical example is presented. The proposed analysis may be used to estimate curvatures or to determine the maximum fabrication temperature and the heating width for a single heating–cooling cycle for steels such as high-performance steel not covered by the current AASHTO provisions.
Context-Sensitive Construction in Kentucky
Authors: Hancher Donn , Goodrum Paul , Pigman Jerry , Hartman Don , Mettille John
Published: April 2007

The development of a new initiative for the Kentucky Transportation Cabinet to involve resident engineers and contractors in the project development process, especially for environmentally sensitive projects, is summarized. To meet the demands of human and natural environmental issues on transportation projects, many departments of transportation are embracing the tenets of context-sensitive design for their projects. Some have begun to expand this involvement to all participants in the project development process and are calling this initiative "context-sensitive solutions." The Kentucky Transportation Cabinet believes that it is critical to involve its resident engineers and contractors in the process to ensure success on environmentally sensitive projects. In the planning and design stages of project development, the commitments that are made are not always carried into the construction stage and implemented. Context-sensitive construction is the integration of the concepts of context-sensitive design into the construction process and adherence to all commitments made during the earlier stages of project development. The Kentucky Transportation Center and the Civil Engineering Department at the University of Kentucky developed a training program to introduce the concepts of context-sensitive solutions for the construction phase of a project to industry and cabinet personnel, and that program is described.
Process for Selecting Strategies for Rehabilitation of Rigid Pavements Under High Traffic Volumes
Authors: Anderson Stuart D. , Ullman Gerald L. , Blaschke Byron C.
Published: April 2007

Many highway facilities are experiencing rapid deterioration because of high traffic volumes and service lives that have been extended beyond the facility design life. State highway agencies (SHAs) are under pressure to mitigate the resulting poor pavement conditions through maintenance, rehabilitation, and reconstruction (MRR) work while accelerating construction, minimizing traffic disruption, reducing accident risk, and improving public acceptance. SHAs have a range of engineering processes for pavement analysis and design. These pavement-related processes focus on pavement condition and the causes of pavement distresses to identify appropriate pavement treatments. Pavement-related processes determine what is done. Traffic and construction management processes, which are non-pavement-related processes, are also commonly considered to identify how the pavement treatment is accomplished. Little information is available on how to integrate these non-pavement-related processes into the MRR strategy selection process for rigid pavements. A process that integrates both the pavement-related and the non-pavement-related aspects of MRR strategy selection is described. A framework that provides the basis for a review of the literature and the collection of data on current practices is presented. A process modeling technique is used to develop details of the selection process. Case studies were developed by using four projects to validate the process. Practical illustrations from case study projects that demonstrate several key steps of the process with respect to traffic- and construction-related issues that influence selection of the most appropriate MRR strategy for rigid pavements under high traffic volumes are presented.
Improved Red Clearance Intervals Based on Observed Turning Times for Left-Turn Movement
Authors: Yu Lei , Qiao Fengxiang , Zhang Yusong , Tian Zong Z.
Published: April 2007

Because of the lack of adequate guidelines and procedures to determine the red clearance interval for the left-turn movement, a common practice for most jurisdictions is to use the same red clearance intervals for both through and left-turn movements. Such a practice may create potential safety and operational concerns because the unique characteristics of left-turn traffic, such as the presence of turning curves and centrifugal forces, are not addressed. To improve the calculation of the red clearance interval for the left-turn movement, a new method was developed and verified by data observed in the field. The actual turning times were collected at 21 intersections in Texas. These intersections vary in speed limit, number of left-turn lanes, and left-turn control type. The red clearance intervals, determined from the proposed methodology, were generally lower than the turning times observed in the field but higher than those currently being used in practice. A validation of the calculation based on the crash analysis was also conducted to support the proposed method.
Driver Understanding of Potential All-White Pavement Marking Patterns
Authors: Hawkins H. Gene , Parham Angelia H. , Womack Katie N.
Published: April 2007

Over the last decade, increasing attention has been devoted to the potential of converting U.S. pavement markings to an all-white system. There are many reasons and potential benefits for doing so. As part of an NCHRP study, researchers conducted many activities to evaluate the feasibility of implementing an all-white marking system in the United States. The research study findings on marking practices in other countries and the results of the driver survey on all-white markings are summarized here. The researchers found that 17 of the 22 countries contacted use an all-white marking system. However, numerous differences exist between the systems used in various countries, so there is no single all-white system on which the United States could base implementation. The survey findings indicate that the all-white markings evaluated in the survey did not have any higher comprehension levels than the current system of yellow-white markings. Therefore, implementation of all-white markings would need to be accompanied by an extensive driver education program. The survey findings indicate that the presence of a solid line as part of the centerline increases understanding of the two-way message of a centerline to about 85%. In developing the survey, the researchers determined that the use of various marking widths or stripe-gap ratios was not effective in conveying messages to drivers. On the basis of the study findings, the researchers recommended an all-white system not be implemented in the United States at this time.
Development of Visibility Assessment Methods with Digital Images Under Foggy Conditions
Authors: Hagiwara Toru , Kizaka Kiyoshi , Fujita Satoshi
Published: April 2007

Basic methods are proposed for assessing poor visibility by using digital images from a road monitoring camera. An experiment was performed over 5 days in 2002 under artificial fog at a laboratory of the National Institute for Land and Infrastructure Management in Tsukuba, Japan. Twenty-one Landolt circles were prepared as targets, each with a different variation of Landolt circle (7 circle sizes X 3 circle-contrast levels). Digital image (8 bits, red-green-blue), illuminance, and transmissivity under artificial fog were recorded together while five subjects assessed the visibility of the circle. First, the digital contrast of the Landolt circle was examined in a digital image in terms of its applicability as a visibility assessment value. Second, the average intensity of grayscale (AIG) of the entire cutout image was examined in terms of its applicability as a visibility assessment value. The magnitude of AIG represented the difference in digital intensities within the image. Digital contrast and AIG were compared with the subjective visibility assessment values (SVAV) given by the subjects. During fog, both digital contrast and AIG increased as transmissivity increased. Relationships were found between both these values and SVAV. However, when digital contrast was used, the relationships depended on circle size. When AIG was used, the relationships depended on SVAV and not on circle size or circle-contrast level. These results suggest that AIG might be more appropriate than digital contrast for assessing subjective visibility level during fog.
Demand-Responsive Pricing Method for the Product Line of Taiwan High-Speed Rail
Authors: Lee Chi-Kang , Tsai Tsung-Hsien
Published: April 2007

Presented is a demand-responsive pricing method for the product line of Taiwan high-speed rail. Considered are the objectives of both the operator and the passenger with their leader-follower and noncooperative relationships. The method is constructed by a bilevel program. A pricing model, which is the upper-level problem, considers three structures: basic model, market differential model, and product differential model. A demand model, which is the lower-level problem, considers service choice of passengers as a logit choice function where market competition is represented by a linear demand function and service capacity is used as a constraint for each service section. In a numerical study of three origin-destination pairs, presented are the results of the pricing models and their associated demand patterns. Convergence and sensitivity of model parameters are analyzed as well. The case study shows promising results for the flexibility and capability of the demand-responsive pricing method.
High-Speed Line Airport Connections in Europe: State-of-the-Art Study
Authors: López-Pita Andrés , Robusté Francesc
Published: April 2007

Throughout the history of the different modes of transport, the idea of intermodal competition has, until very recently, dominated viewpoints. In the past 10 years, however, recognition of the need for collaboration between rail and aviation transport has become increasingly evident, mainly as a result of increased mobility. Since the 1950s, in Europe, rail transport has been the prevailing method used to connect urban centers to their respective airports. With the introduction of high-speed rail service, however, a distinctly new type of collaboration between both transport modes has appeared, for through the use of high-speed rail connections, travelers from areas located as far as 300 to 400 km from the urban center can reach the airport with ease. Presented are the current transport solutions that have been adopted by certain European airports in regard to high-speed rail. There is also an objective to reach some conclusions that could be of interest to the airports in Europe or around the world that are not currently using high-speed rail service.
Information Requirements for Railroad Enterprise Asset Management: Practical Approach on Amtrak's High-Speed Northeast Corridor Railway Line
Authors: Marcolongo Valerie , Ebersöhn Willem , Trosino Michael J.
Published: April 2007

Providing a safe, reliable, and maintainable railway infrastructure is a formidable challenge in Amtrak's complex operating environment. Presented is the design description of the Infrastructure Information Management database, including the latest developments and incorporating vehicle-track interaction measurements. Also shown is how wayside measurements combined with a record of train movement to define the traffic and utilization of the railway infrastructure. An example of the use of the system is discussed to illustrate how the combined information will assist the maintenance managers in determining when and where to invest resources to optimally maintain the railway infrastructure. Also addressed is how wayside and record of train movement can be used to allocate maintenance costs to the various service providers.
Objective Track Quality Indices
Authors: El-Sibaie Magdy , Zhang Yu-Jiang
Published: April 2007

A set of new track quality indices (TQIs) has been developed to aid in the evaluation of track geometry measurements and to complement the well-established track classification based on the Federal Track Safety Standards (FTSS). The newly developed TQIs will be eventually implemented as real-time processed indicators on FRA's research vehicle, the T-16. After a review of existing methods for determining TQIs, it is concluded that none of the current methods can satisfy the stated objectives. Therefore, a new methodology has been developed and tested to compute TQIs from track geometry data based on a simple and intuitive approach. The results have shown that the new TQIs can quantitatively describe the relative condition of track surface geometries. Furthermore, it is shown that the new TQIs are well correlated to the FTSS for each track class, providing a relative indication of quality within each class. A total of 48 track geometry surveys are selected from measurements taken by the FRA T-2000 track geometry car. Track geometry data from these surveys are processed and divided into 528-ft segments. For each track segment, the FTSS is used to determine actual track class. The track segments are grouped according to the actual classes these segments meet. Track quality indices are computed over each track segment. The results are used to establish TQI thresholds for each track class. The findings indicate that there are distinct TQI ranges for each track class, although there is some overlap between the upper boundary of one class and the lower boundary of the next.
Value Pricing Toll Program at Port Authority of New York and New Jersey: Revenue for Transportation Investment and Incentives for Traffic Management
Authors: Muriello Mark F. , Jiji Danny
Published: April 2007

On March 25, 2001, the Value Toll Pricing Program of the Port Authority of New York and New Jersey was introduced at the two tunnels and four bridges that connect New Jersey with New York City. Since that time the program has generated incremental revenue to support an aggressive intermodal capital investment program and has also produced traffic management benefits to address congestion. The program represents one of the most aggressive applications of value pricing on existing toll facilities in the United States. Given the level of congestion experienced in the New York-New Jersey region on a daily basis, the program has generated meaningful steps in addressing traffic congestion through market incentives. The genesis of the program as a revenue enhancement to finance an aggressive new intermodal capital investment program is discussed. The traffic management benefits of the program are then explored, as well as the program's effectiveness in addressing five key policy objectives established for the effort.
Credit-Based Congestion Pricing: Travel, Land Value, and Welfare Impacts
Authors: Kalmanje Sukumar , Kockelman Kara M.
Published: April 2007

The possible transportation and property value impacts of a new congestion management policy called credit-based congestion pricing (CBCP) are explored. With destination, mode, and departure-time choice models sensitive to changes in travel times and costs, household travel demands were simulated to appreciate the transportation effects of a CBCP policy for Austin, Texas. Changes in home values as a result of CBCP also were simulated. To identify households and neighborhoods that would benefit most and least from such policies, the trip-based welfare impacts of such a policy were compared for three scenarios: full network pricing, major highway pricing only, and no pricing. Results corroborate previous results and hypotheses about the potential of a CBCP policy to alleviate congestion and generate benefits across the region and traveler types.
Per Mile Costs of Operating Automobiles and Trucks
Authors: Barnes Gary , Langworthy Peter
Published: April 2007

A methodology and simple model for use in benefit-cost analysis of highway projects are described for calculating the variable per mile costs of operating cars and trucks. Although the marginal vehicle operating costs generated by changes to trip mileage or operating conditions are typically a small part of total project costs, they can be significant in deciding among alternative designs, construction scenarios, or project timing. Operating costs for personal vehicles (autos, pickups, SUVs, vans) are developed primarily from consumer guides, with an overall fleet average cost based on vehicle sales. Operating costs for large commercial trucks are based on a review of a number of sources of trucking costs. Factors for adjusting the costs based on stop-start conditions, pavement roughness, and inflation are derived from various sources. Results are that in a "baseline" case of highway driving on smooth pavement, with a fuel price of $1.50 per gallon and other costs in 2003 dollars, personal vehicles average 17.1 cents per mile to operate and trucks average 43.4 cents per mile, not counting costs associated with the driver or travel time. City driving conditions, involving frequent stops and starts, increase this cost by 3.9 cents per mile for personal vehicles and 9.5 cents for trucks. Extremely rough pavement increases the baseline cost by 2.7 cents for personal vehicles and 5.5 cents for trucks.
Transportation and the Economy: Linkages at Business-Cycle Frequencies
Authors: Lahiri Kajal , Yao Wenxiong , Young Peg
Published: April 2007

Transportation plays a central role in facilitating economic activities across sectors and between regions and is essential to business-cycle research. With four coincident indicators that represent different aspects of the transportation sector—an index of transportation output, payroll, personal consumption, and employment—the classical business-cycle and growth-cycle chronologies are defined for this sector. It is found that, relative to the economy, business cycles in the transportation sector have an average lead of nearly 6 months at peaks and an average lag of 2 months at troughs. Similar to its business cycles, growth slowdowns in the transportation sector also last longer than the economywide slowdowns by a few months. This study underscores the importance of transportation indicators in monitoring cyclical movements in the aggregate economy.
Development of Quantification Method for Measuring Travel and Emissions Impacts of Episodic Ozone Alert Programs
Authors: Lu Joann , Weir Jeff , Schreffler Eric N. , McLarney Timothy , Sarles Richard , Higgins Thomas , Johnson Will
Published: April 2007

Many air quality management districts throughout the country conduct public education programs during the summer ozone season to encourage members of the public to reduce their driving on days forecast to violate ozone air quality standards. The research study developed a relatively simple and low-cost method for quantifying the travel and emission impacts of these programs, often called "Spare the Air" in California. The study developed survey methods that included both a long, detailed questionnaire and a short, simple one. Through these questionnaires, the study collected comprehensive travel data of a random sample of the general population and of individuals who said they responded to the Spare the Air (STA) message. The data, collected during two summer ozone seasons in Sacramento, allowed researchers to compare the travel behavior of the same individuals on both STA and regular (non-STA) summer days and of STA participants and nonparticipants. The study found a statistically significant difference between self-reported vehicle trip reductions and measured vehicle trip changes due to STA programs among STA participants. A correction factor was derived based on this research finding. By applying the correction factor to a simple and less costly survey, similar to the simple questionnaire used in this study, air districts will be able to adjust future self-reported vehicle trip reductions and extrapolate them to the entire regional population of drivers within an acceptable margin of error.
Effects of a Controlled Auditory–Verbal Distraction Task on Older Driver Vehicle Control
Authors: Rizzo Matthew , Stierman Laura , Skaar Nicole , Dawson Jeffrey D. , Anderson Steven W. , Vecera Shaun P.
Published: April 2007

Engaging in conversation diverts attention from cognitive processes associated with driving. Drivers tend to commit errors that may lead to crashes when their attention is focused away from the driving task. The interference occurs at the level of central attentional processes that are especially susceptible to aging. The current study assessed the effects of a controlled auditory—verbal processing load induced by the Paced Auditory Serial Addition Task (PASAT) on vehicle control by 160 legally licensed older drivers. Of these drivers, 78 were neurologically normal (mean age of 71 years) and 82 (mean age of 75 years) had impairments of selective attention but no diagnosable neurological disease. Measurements aboard the instrumented vehicle Automobile for Research in Ergonomics and Safety showed that performing the PASAT reduced speed and steering control of the older drivers relative to baseline (no-task) driving conditions and was associated with greater counts of at-fault safety errors. Yet, driving performance did not differ significantly between neurologically normal and attention-impaired older drivers between PASAT and no-PASAT (baseline) conditions. It may be that the PASAT, which involves auditory-verbal and working-memory, sustained-attention, and executive-function components, commands different resources than driving on uneventful highways, which might rely on overlearned, automatic cognitive processes. Interference produced by PASAT, like that of cell phone operation, might become more evident during demanding driving conditions, as exist at busy traffic intersections. Relevant studies in these potentially unsafe circumstances can be conducted in a driving simulator, as in our ongoing research on older drivers.
Older Drivers and Cataracts: Measures of Driving Performance Before and After Cataract Surgery
Authors: Wood Joanne M. , Carberry Trent P.
Published: April 2007

Cataracts are the main cause of reversible vision impairment in older adults. An investigation examined how cataracts and cataract surgery affected driving performance and determined whether any changes in driving performance could be predicted by self-reported perceptions of driving and vision. Twenty-eight older participants with bilateral cataracts and eighteen age-matched control participants with normal vision were tested. All were licensed drivers. Driving and vision performance were measured before cataract surgery, after first-eye surgery, and again after second-eye surgery for the cataract participants and on three separate occasions for the control group. Driving performance was assessed on a closed-road circuit. Visual acuity and contrast sensitivity were also measured at each test session. Self-perceptions of vision and driving were assessed with the Activities of Daily Vision Scale (ADVS). The participants with cataracts had significantly poorer ( p <.05) driving performance at the first visit compared with the control participants for a range of measures of driving performance, which significantly improved to the level of the control participants following cataract extraction. Self-perceived changes in driving performance assessed with the ADVS were not strongly related to the actual changes in driving performance recorded. Together these findings indicate that participants with cataracts have poorer driving and vision performance than age-matched control participants and that cataract surgery can result in significant improvements in driving, which are not predicted by self-reported measures such as the ADVS.
Effect of Yellow-Interval Timing on the Frequency of Red-Light Violations at Urban Intersections
Authors: Bonneson James A. , Zimmerman Karl H.
Published: April 2007

Statistics indicate that red-light running has become a significant safety problem throughout the United States. There is a wide range of potential countermeasures to the problem of red-light running; an increase in yellow duration is one countermeasure. The objective of this research was to quantify the effect of a change in yellow-interval duration on the frequency of red-light violations. A before-after study is described and the resulting data are used to quantify the effect of increasing the yellow interval on the frequency of red-light violations. Based on this research, it was concluded that ( a) an increase of 1.0 s in yellow duration (such that it does not exceed 5.5 s) will decrease the frequency of red-light violations by at least 50%; ( b) drivers do adapt to the increase in yellow duration, but this adaptation does not undo the benefit of an increase in yellow duration; and ( c) increasing a yellow interval that is shorter than the value obtained from a proposed recommended equation published by the Institute of Transportation Engineers is likely to yield the greatest return (in terms of a reduced number of red-light violations) relative to the cost of retiming a yellow interval in the field.
Best Practices in Managing School Campus Traffic Circulation
Authors: Tsai Jeff , Cranford Joel , Lee Jae-Joon
Published: April 2007

Working with the North Carolina Department of Transportation, Municipal and School Traffic Assistance Program, a research team from the Institute for Transportation Research and Education at North Carolina State University studied the traffic at 20 elementary school campuses during the peak afternoon school-travel hours. Study results led to several observations and recommendations. On average, 60% of carpool vehicles arrived in the carpool lane before the afternoon school dismissal time and spend an average of triple the amount of time of those who arrived shortly after the bell-ring time. Establishing multiple loading bays and staffing each bay with safety patrol to assist loading can greatly reduce vehicle loading and unloading time. The act of loading and unloading students should take less than 10 s per vehicle; the complete process of a vehicle entering, loading and unloading passengers, and then exiting can be completed in less than 45 s. Limiting options for drivers will reduce circumventions that may lead to crashes. If spillage onto adjacent roadways is a problem, a double lane for the queue at some point in the carpool lane is a viable solution. School traffic congestion can be addressed by encouraging a mode shift from private vehicles to school bus transportation, walking, or biking. To convey the study results to school administrators and to illustrate recommendations, a website (www.itre.ncsu.edu/stg) was created; it contains a simple decision tree to assist administrators in identifying the nature of a traffic concern and to provide recommendations for appropriate solutions. It also illustrates schematics of the optimal layout for loading and unloading students, with explanations of the recommended operating procedures and video clips of actual operations.
Effect of Day Length on Sleep Habits and Subjective On-Duty Alertness in Irregular Work Schedules
Authors: Pilcher June J. , Teichman Heather M. , Popkin Stephen M. , Hildebrand Krista R. , Coplen Michael K.
Published: April 2007

The human circadian system is sensitive to environmental conditions, such as those created by shift work, that affect the timing and duration of sleep. Previous research on the effects of shift work, however, has focused primarily on regularly scheduled shifts. Few studies have focused on irregular and unpredictable on-call shift systems, such as those found in much of railroad operations. The purpose of the current study was to examine the effect of irregular shift systems experienced by locomotive engineers on the length of sleep-wake periods and the effect of different length sleep-wake periods on self-reported sleep quantity, sleep quality, and on-duty alertness. A total of 179 locomotive engineers provided information on work times, sleep habits, and on-duty alertness as part of a 14-day activity log. Sleep-wake periods were first divided into three categories: short (<22 h), normal (22 to 26 h, inclusive), and long (>26 h). A one-way analysis of variance for multiple variables was completed on sleep quantity, sleep quality, and on-duty alertness by using the three sleep-wake period categories as the factor. The results indicated that normal-length periods occurred in less than half of the sleep-wake periods. The remaining sleep-wake periods were divided approximately equally between short and long periods. In addition, short sleep-wake periods resulted in less sleep and generally poorer sleep than normal length sleep-wake periods. Long sleep-wake periods resulted in more sleep but poorer sleep and lower levels of on-duty alertness than normal sleep-wake periods. Furthermore, on-duty alertness followed a circadian rhythm with the most well defined rhythm seen in normal length sleep-wake periods and less pronounced rhythms seen in short and long sleep-wake periods. The current data indicated that the range of sleep-wake periods caused by irregular working conditions negatively impacted sleep habits and on-duty alertness in locomotive engineers.
Inventory System for Retaining Walls and Sound Barriers
Authors: Hearn George , Abu-Hejleh Naser , Koucherik James
Published: April 2007

An inventory system for retaining walls and sound barriers includes information about location, age, service, type, dimensions, and appraisals of a structure together with element-level models and element-level condition reports. Many of the inventory items and appraisals are adapted from the U.S. National Bridge Inventory record. Elements for walls and barriers indicate structural form and material, much like Commonly Recognized (CoRe) bridge elements. Potential uses of the inventory system in maintenance management and asset preservation are noted.
Another View of Truck Lane Restrictions
Authors: Cate Matthew A. , Urbanik Thomas
Published: April 2007

As truck volumes on U.S. highways continue to increase, both elected officials and members of the general public often look to the use of lane restrictions for large trucks as a means to increase operating efficiency and highway safety. In the past, research has offered little evidence that either safety or efficiency is positively affected by widespread use of this practice. Another view of truck lane-use restrictions on high-speed, limited-access facilities is offered. To determine the effects of lane-use restrictions, scenarios that varied traffic characteristics such as volume, grade, percentage of trucks, and the presence of entrance and exit ramps were developed with the VISSIM model. In each scenario traffic along the model freeway segment was monitored to determine the effect of the lane-use restrictions by comparing values of various traffic measures from a model run first without and then again with truck lane restrictions. As in past research efforts, the implementation of truck lane restrictions in a variety of scenarios is shown to have little effect on a number of traditional measures, including average speed, speed differential between cars and large trucks, and level of service. However, further examination of data resulting from the simulation process shows that significant gains in the area of safety and driver comfort may be realized through the reduction of lane-changing maneuvers by all vehicle types, lending support to past driver surveys indicating strong support for this practice among drivers of passenger vehicles.
Cross-Correlation Tracking Technique for Extracting Speed from Cameras Under Adverse Conditions
Authors: Schoepflin Todd N. , Dailey Daniel J.
Published: April 2007

An algorithm to estimate speed from traffic surveillance cameras in a variety of traffic congestion, weather, and lighting conditions is presented. The features from the images are projected into a one-dimensional sub-space and transformed into a linear coordinate system by using a simplified camera model. A cross-correlation technique is used to summarize the movement of features through a group of images and to estimate mean speed for each lane of vehicles. A Kalman filter technique with a set of maximum-likelihood optimal parameters is used to estimate the traffic speed by lane to create an optimal space-averaged speed.
Methodology for Measuring Recurrent and Nonrecurrent Traffic Congestion
Authors: Dowling Richard , Skabardonis Alexander , Carroll Michael , Wang Zhongren
Published: April 2007

A methodology is presented for estimating and predicting the total annual traffic congestion attributable to recurrent and nonrecurrent congestion. The methodology is applicable to freeways, conventional highways, and urban streets. The methodology is sensitive to improvements in facility surveillance and freeway service patrol strategies. Recurrent congestion is estimated by using Highway Capacity Manual speed-flow curves and data on facility demands, free-flow speeds, and capacities. Nonrecurrent congestion is estimated in terms of annual vehicle hours of delay caused by weather, work zones, incidents, and so forth. The methodology employs incident probability trees, incident duration (sensitive to surveillance and response times), and estimates of remaining capacity during incidents to estimate incident delay. Weather-and work-zone-related delays are estimated on the basis of frequency of occurrence and estimates of capacity reductions during periods of bad weather and work-zone activity. The methodology has been implemented in a spreadsheet.
Estimation of Travel Times on Urban Freeways Under Incident Conditions
Authors: Hobeika Antoine , Dhulipala Sudheer
Published: April 2007

Travelers on urban freeways are interested in knowing how long it will take them to reach their destinations, especially under bottleneck, congested, and incident conditions. Travel time information is important for advanced traveler information systems (ATIS) applications and for assessing the performance of the transportation network. Though many advances have been made in the field of traffic engineering and intelligent transportation system applications, practical travel time estimation procedures for ATIS applications under incident conditions are lacking. An algorithm for travel time estimation on urban freeways for ATIS applications under incident conditions is presented. The algorithm is based on point estimates of traffic variables obtained from detectors placed on every link of the freeway network. The output required from the detectors is flow and occupancy aggregated for a short time interval (5 min). The system for travel time estimation is based on traffic flow theory rather than on statistical methods. The travel times calculated using this system are compared with the results obtained using the FHWA microsimulation computer package CORSIM in the Traffic Software Integrated System (TSIS) Version 5.0. The algorithm results are found to be reasonable and accurate compared with CORSIM results.
Red Clearance Intervals: Theory and Practice
Authors: Muller Theo H. J. , Dijker Thomas , Furth Peter G.
Published: April 2007

At signalized intersections the red clearance interval has to be long enough to prevent accidents but not longer than necessary to ensure efficient traffic operations and encourage respect for the red indication. Because designers used a variety of methods to calculate clearance times, the association of Dutch traffic control engineers (Contactgroep Ver-keersregeltechnici Nederland) initiated the development of a generally applicable method. The resulting method is based on a driver behavior model that involves five parameters. In contrast to the suggested Institute of Transportation Engineers (ITE) method, it determines red clearance time for each ordered pair of conflicting streams depending on the distance of the entering and exiting streams from the zone in which the two streams' paths overlap. The conflict zone method was calibrated by using field data collected at two intersections and was included in the 1996 Dutch guidelines for traffic controllers. In comparison with the ITE-suggested method, which gives the exiting stream enough time to clear the entire intersection, the new method is sensitive to the sequence in which traffic streams appear in the cycle and tends to call for less clearance time, improving intersection capacity and reducing delay. This approach is especially beneficial in improving efficiency of intersections with actuated control.
Optimal Detector Location for Bus Signal Priority
Authors: Liu Hongchao , Skabardonis Alexander , Zhang Wei-bin , Li Meng
Published: April 2007

A theoretical model is presented to quantitatively address the relation between bus detector location and effectiveness of transit signal priority (TSP) systems, supplemented by a sample model application and simulation experiments on a real-world arterial corridor. The simulation results agree very well with results from the theoretical model. The findings of this research contribute to a better understanding of the interaction of the various components of TSP systems, which can lead to better TSP design and implementation.
Simple Worksheet Method to Evaluate Emergency Vehicle Preemption and Its Impacts on Safety
Authors: Louisell Chuck , Collura John , Teodorovic Dusan , Tignor Sam
Published: April 2007

Providing safe and efficient public safety services is a primary function and obligation of local governments. Rapid growth and congestion coupled with the increasing need to provide safe and efficient arterial access to first responders have challenged public officials seeking to make budget decisions that support higher levels of fire and rescue service quality. Emergency vehicles (EVs) operating in higher congestion levels are at risk for involvement in crashes and delays in reaching the scene of a fire or accident. One means to offset the effects of congestion is installation of emergency vehicle preemption (EVP) equipment at signalized intersections. This intelligent transportation system technology provides a special green interval to the EV approach while providing a special red interval on all conflicting approaches. The effects of EVP are a reduction in exposure to active conflict points, thereby reducing crash potential, and dispersion of the queues, thereby allowing the EV to maintain higher average operating speeds along the response route. The problem faced by local policy makers and by transportation and public safety officials is that there are no national guidelines or methods to aid in the evaluation of intersections and corridors under consideration for EVP deployment. One element of this issue is addressed: the need for a method to evaluate the safety benefits of EVP for one intersection or corridor over another in relative terms. It proposes a simple tool, usable in safety audits and engineering studies, to determine which intersections or corridors would benefit most from EVP.
Inclement Weather and Traffic Flow at Signalized Intersections: Case Study from Northern New England
Authors: Agbolosu-Amison Seli J. , Sadek Adel W. , ElDessouki Wael
Published: April 2007

Gridlock along arterial systems in New England is often the result of adverse weather conditions, which can render the normal signal plans unsuitable. The current study has two main objectives: ( a) to assess the impact of inclement weather on traffic flow parameters at signalized intersections in northern New England and ( b) to evaluate the likely operational benefits of implementing special timing plans for inclement weather conditions. A signalized intersection in Burlington, Vermont, was selected, and at least 30 h of videotaped data were collected over a period of 3 months. The weather and road surface conditions were categorized into six different classes, and values for the saturation headways and start-up lost times were collected and statistically analyzed. A signalized collector was then selected as a case study for evaluating the likely benefits of developing special timing plans for inclement weather. Optimal signal plans were developed for the corridor for the six different weather conditions. The likely benefits of the special plans were then determined by comparing travel conditions under the optimal inclement weather timing plans with conditions assuming the optimal dry-condition plan would remain unchanged. The study reveals that inclement weather has a significant impact on saturation headways, particularly once slushy conditions start. Start-up lost time, however, does not appear to be significantly affected by inclement weather. The study also shows that there are benefits to be expected from implementing special signal plans for inclement weather.
Modeling Impact of Ramp Metering Queues on Diamond Interchange Operations
Authors: Tian Zong , Messer Carroll , Balke Kevin
Published: April 2007

Methodologies to model the impact of ramp metering queues on diamond interchange operations were developed in this study. The methodologies are part of an overall research effort to address the integrated operations of a diamond interchange and a ramp metering system. The methodologies were implemented in DRIVE, a computer model characterized as a mesoscopic simulation and analytical model. A meso-scopic model has the advantages of both macroscopic and microscopic models with less computing time while still considering stochastic traffic flows. DRIVE can be used to perform system analysis and evaluation of an integrated diamond interchange and ramp metering system over multiple cycles. The component concerning the diamond interchange operations is documented here, with a particular focus on the impact of potential queue spillback to the diamond interchange signals from ramp metering. The study focused on the two common diamond phasing schemes: basic three-phase and Texas Transportation Institute (TTI) four-phase. DRIVE was validated against the VISSIM microscopic traffic simulation model, and general agreement was found in the results between the two models. For oversaturated ramp conditions with queue spillback, both DRIVE and VISSIM indicated that TTI four-phase favors the frontage road approach, whereas the basic three-phase favors the arterial left-turn movement. DRIVE provides a new analysis tool for analyzing diamond interchange operations taking ramp metering into consideration, which would facilitate studies on developing operational strategies to better manage such systems.
Configuration of Traffic-Responsive Plan Selection System Parameters and Thresholds: Robust Bayesian Approach
Authors: Abbas Montasir M. , Sharma Anuj
Published: April 2007

Traffic-responsive plan selection (TRPS) is one of the two major closed-loop system modes of operation. The TRPS mode is more beneficial than its competitor (time-of-day mode) because of its ability to accommodate abnormal traffic conditions such as incidents, special events, and holiday traffic. However, no guidelines are available for optimal setup of TRPS systems. Improper configuration of a TRPS system can result in inefficient system performance or unstable operation in which the closed-loop system operates in a perpetual transitioning state. The TRPS mechanism implemented in current traffic signal controllers is described, and a Bayesian-based methodology for selecting an optimal set of TRPS factors, parameters, and thresholds is proposed. The proposed methodology was tested with data from a closed-loop system in Texas and resulted in 100% classification accuracy.
Comparison of Commodity Flow Forecasting Techniques in Montana
Authors: Waliszewski Janine M. , Ahanotu Dike N. , Fischer Michael J.
Published: April 2007

Two methods for developing commodity flow forecasts at a substate level of geography are described. The first process is a simplified method that relies entirely on the commodity percentage increases provided at the state level in the FHWA freight analysis framework database. The second method uses a combination of substate employment data and input-output analysis to distribute the forecasted growth for each commodity to each zone in the study area. The differences between these two methods are shown geographically and in table form at the county level of detail. Additionally, a chi-squared goodness-of-fit test is used to determine whether the two forecasting methods are statistically different for inbound, outbound, and internal flows. Most of the analysis was taken from the commodity flow freight forecast created for the Montana Department of Transportation highway reconfiguration study. The results of this comparison are discussed in the context of the transportation planning decisions that potentially are improved by using the enhanced rather than the simplified forecasting method.