bluuebunny/crossref_metadata_2025 huggingface dataset:
Using a Fuzzy Quality Function Deployment Model to Identify Improvement Points in Airport Cargo Terminals
Authors: Liang Gin-Shuh , Han Tzeu-Chen , Chou Tsung-Yu
Published: May 2018

The main purpose of this paper is to present a fuzzy quality function deployment model to achieve service quality assurance before implementing service action. First, customer needs with their importance and satisfaction levels acquired from practical investigations are constructed. Then, by combining the experts’ opinions, service management requirements are developed for satisfying the observed customer needs. In addition, a fuzzy relation matrix for linking service management requirements to customer needs is constructed on the basis of cross-functional expertise. The aggregated fuzzy assessments of different service management requirements are also ranked to prioritize and determine their importance. Finally, the Chiang Kai-shek International Airport cargo terminal in Taiwan is used to demonstrate the proposed approach.
Early-Age Strength Assessment of Cement-Treated Base Material
Authors: Guthrie W. Spencer , Young Tyler B. , Blankenagel Brandon J. , Cooley Dane A.
Published: May 2018

To avoid early-age damage to cement-treated base (CTB) materials, the cement must be allowed to cure before the pavement can be opened to traffic. The purpose of this research was to evaluate the utilities of the soil stiffness gauge (SSG), the heavy Clegg impact soil tester (CIST), the dynamic cone penetrometer, and the falling weight deflectometer for assessing early-age strength gain of cement-stabilized materials. Experiments were performed at four sites on a pavement reconstruction project along I-84 in Morgan, Utah, where cement stabilization was used in conjunction with full-depth recycling. Each site was stationed to facilitate repeated measurements at the same locations with different devices and at different curing times. Because of the considerable attention from the pavement construction industry for routine quality control and quality assurance programs, the SSG and CIST were the primary focus of the research. Statistical techniques were used to evaluate the repeatability of these devices and their sensitivity to curing time. The results indicated that although the SSG was more repeatable at one site, the CIST data were markedly more sensitive to curing time than the SSG data at all cement-treated sites during the first 72 h after construction. For this reason, the data suggest that the CIST offers greater overall utility than the SSG for monitoring early-age strength gain of CTB. Further research is needed to investigate appropriate thresholds and protocols for these testing methods that ensure adequate reliability of the collected data.
Cyclic Plate Load Testing of Geosynthetic-Reinforced Unbound Aggregate Roads
Authors: Tingle Jeb S. , Jersey Sarah R.
Published: May 2018

A laboratory research program designed to investigate geotextile and geogrid reinforcement of the aggregate layer in unbound pavement sections was performed by the U.S. Army Engineer Research and Development Center. The investigation's objective was to evaluate the performance of geosynthetic-reinforced aggregate road sections over a very soft subgrade. Standard construction materials were used to construct six aggregate road sections in a large steel box. Each instrumented road section was subjected to cyclic plate load tests to evaluate the performance of the model pavement sections under simulated truck traffic. The mechanistic response and permanent deformation of each instrumented pavement section were monitored periodically during each test. Analysis of the experiment data indicated that the geosynthetics improved the performance of the reinforced pavement sections compared with the unreinforced section in terms of improved load distribution and reduced permanent deformation or rutting. Additional information regarding the reinforcement mechanisms is summarized.
Full-Scale Experimental Measurement of Barge Impact Loads on Bridge Piers
Authors: Consolazio Gary R. , Cowan David R. , Biggs Alexander , Cook Ronald A. , Ansley Marcus , Bollmann Henry T.
Published: May 2018

Bridges that span navigable waterways must be designed to resist potential impact loads associated with barge or ship collisions. Despite this fact, few experimental data have been collected about the magnitude and nature of such loads. Vessel-impact components of bridge design specifications, such as the AASHTO bridge design provisions, are therefore based on limited experimental data. Recently, a bridge in the United States (Florida) was replaced with a new structure and thus afforded a unique opportunity to conduct full-scale barge impact tests on piers of the preexisting structure before it was demolished. Tests were conducted on two piers with fundamentally different types of foundation systems. Tests on one pier also were repeated in two structural configurations (with the superstructure present and then with it removed). In each test, instrumentation and high-speed data acquisition systems were used to quantify the dynamic loads generated during controlled collision events. Experimental procedures used during the tests are described, and selected test results are presented, including experimentally measured dynamic impact loads and associated barge deformations. Comparisons are then presented between experimentally collected data and the current AASHTO barge impact bridge design provisions.
Pore Pressure Measurement in Blast-Induced Liquefaction Experiments
Authors: Rollins Kyle M. , Lane J. Dusty , Dibb Emily , Ashford Scott A. , Mullins A. Gray
Published: May 2018

Blast-induced liquefaction experiments have been conducted at a number of test sites to evaluate lateral foundation resistance and soil improvement techniques. Tests can be constructed at full scale without waiting for an earthquake. In this extreme environment, pore pressure transducers must survive transient blast pressures of 41.4 MPa (6,000 psi) yet have enough resolution to measure residual pore pressures of ±0.69 kPa (0.1 psi). Three transducer types were evaluated under these demanding conditions, and the piezoresistive transducer was found to be the most robust. These sensors were repeatedly subjected to extreme blast pressures and vibration, but they still provided accurate time histories of residual pore pressure. Although these piezometers are more expensive than other types, installation techniques allowed them to be recovered and reused in subsequent tests and thus reduced overall costs. These pore pressure sensors make it possible to define the extent of the liquefied zone during blast liquefaction experiments and to understand the soil behavior during cyclic loading of deep foundations.
Challenges of Measuring Performance for FAA's Safety Oversight System
Authors: Hansen Mark , McAndrews Carolyn
Published: May 2018

FAA regulates the safety of the aviation industry through the safety oversight system, which is a system of rulemaking, standard-setting, certification, accident investigation, rule enforcement, and surveillance activities. Federal programs, including those of FAA, use performance indicators to measure the achievement of program goals. As part of a broader program of developing risk management methodologies, FAA is researching performance indicators that can be used to measure the performance of the safety oversight system. One of its goals is to create performance indicators that can describe the safety oversight system's influence on safety outcomes such as fatalities. Creating performance measures that link activities to safety outcomes is challenging because it is difficult to establish the causation between oversight activities and these safety outcomes. This challenge is not unique to FAA, and external reviewers such as the Government Accountability Office have recommended that other high-reliability sectors, including rail, develop such indicators. In addition to safety outcomes, other aspects of safety oversight system performance can be described with meaningful metrics. The background and motivation for oversight evaluation in the aviation industry and in general are discussed, as well as the challenges, some generic and some unique, of evaluating aviation safety oversight activities. Research is also presented on how safety oversight evaluation is conducted outside aviation.
Effects of Interface Workload of In-Vehicle Information Systems on Driving Safety
Authors: Chen Wan-Hui , Lin Chih-Yung , Doong Ji-Liang
Published: May 2018

Driver distraction and lack of awareness of the driving situation are major causes of accidents in the urban areas in Taiwan; failing to obey traffic signals is the third leading accident cause. Numerous innovative in-vehicle information systems (IVIS) could be used collectively to provide drivers with a variety of information, such as messages from intersection collision warning systems (ICWS) by way of different in-vehicle interfaces. How the different IVIS interfaces influence driver workload and safety is always an important issue. This study investigates the effects of auditory ICWS messages on driver performance while the driver's visual, hearing, or mental processing attention resources (or all three) are engaged by secondary tasks. This type of engagement or distraction commonly occurs when a driver uses IVIS. The secondary tasks used to distract drivers were created by different types of mathematical questions presented with different types of display devices (e.g., voice from a speaker or numbers shown on a liquid crystal display screen or head-up display). Mixed linear models were employed to examine the factors influencing driver perception–reaction time with the consideration of repeated measures. Several factors, including several main factors and an interaction, were found to be significant. The most important finding was that the interaction between provision of ICWS information and the display format indicated that an auditory warning message could increase driver perception–reaction time while a driver was distracted by an auditory task. In addition, it was found that driver distraction due to different mental processing tasks had a significant impact on driver perception–reaction time.
Traffic Safety Evaluation of Video Advertising Signs
Authors: Smiley Alison , Persaud Bhagwant , Bahar Geni , Mollett Calvin , Lyon Craig , Smahel Thomas , Kelman W. Leslie
Published: May 2018

Road authorities are under increasing pressure from advertisers to allow video advertising in the right-of-way but are understandably concerned about whether video signs constitute a driving hazard. At the City of Toronto's request, a comprehensive assessment of traffic safety impacts related to such signs was carried out in a series of studies involving three downtown intersections and an urban expressway site. An on-road eye fixation study was carried out to determine if drivers look at video advertising signs. Conflict studies were conducted to determine if there were more conflicts on intersection approaches with visible video signs than on those without such signs. A before-and-after sign installation study of headways and speeds on the urban expressway was carried out. Crashes were compared before and after sign installation at the expressway and three intersection sites. Finally, a public survey was conducted to determine if video advertising was perceived to affect traffic safety. On the basis of the eye fixation study and the public survey data, it is apparent that video advertising can distract drivers inappropriately and lead to individual crashes. However, the evidence from other studies was not consistent and suggests that for the particular signs studied, overall impacts on traffic safety are likely to be small. Further studies, especially prospective ones with larger crash data sets, are required to be certain about the findings. A comparison between this study and an earlier one suggests that there are large differences in driver distraction depending on the placement and the environment in which the sign is seen. Further studies are required to determine factors that minimize driver distraction.
Reducing Security Risk for Transportation Management Centers
Authors: Rowshan Shahed , Sauntry William C. , Wood Thomas M. , Churchill Bruce , Levine Steve R.
Published: May 2018

Transportation management centers (TMCs) make an important difference in the lives of commuters around the country every day. Various types of threats could damage or destroy a TMC's ability to operate. These threats range from rare but devastating terrorist attacks to the more frequent and troublesome utility failures and severe weather conditions. The TMC risk assessment methodology (RAM) introduced in this paper is based on the best practices of several proven RAMs. Its components include asset identification, threat assessment, consequence assessment, vulnerability assessment, and countermeasure development. The research team selected 10 TMCs as a basis for gathering best practices and common challenges. As initial data were developed for the 10 centers, three sites were chosen to participate in more comprehensive on-site vulnerability assessments. This paper provides general recommendations that can be readily applied to all TMCs. These recommendations include taking the time to conduct a comprehensive risk assessment; reviewing, updating, and revising the risk assessment on a regular basis; correcting simple physical vulnerabilities; and training employees in security awareness.
Innovative Security Technologies for the Transport of Milk
Authors: Koziol Joseph S. , Hoaglund Robert
Published: May 2018

Since September 11, 2001 (9/11), Americans have become more sensitive to the security of their surroundings, including the security of the national food supply. On February 7, 2003, the U.S. Department of Justice increased the nation's terrorist threat assessment level to orange (high risk). Subsequently, the U.S. Department of Agriculture in conjunction with the Food and Drug Administration asked the agriculture community to increase its security precautions. This meant heightening physical security on farms, limiting farm contacts to essential individuals needed to continue operations, increasing security for tanker trucks that ship milk from one plant to another, and adding other security precautions. Better security policies, procedures, and technologies are being sought and continue to be identified and implemented. This paper describes innovative transportation security technologies that have either been implemented or identified to enhance the domestic transport of milk from the farm to the consumer. Although potential vulnerabilities exist throughout the milk supply chain (e.g., at the farm, the processing facility, and distribution center), the transport of milk involves increased exposure and the risk of intentional tampering and contamination. The focus of this paper is on the transport element of the milk supply chain, particularly on the link from the farm to the processing facility, and on the emerging technological countermeasures being used to prevent and mitigate incidents that could lead to the contamination of milk. The innovative transport technologies examined in this paper include electronic seals, electronic manifests, management and tracking systems, and automatic hatchways. These innovative technologies are summarized and discussed in terms of their potential synergistic effects, their potential for addressing vulnerabilities, and the practical obstacles to their implementation.
Times of Bicycle Crossings
Authors: Rubins Daniel I. , Handy Susan
Published: May 2018

The current state of the practice for traffic signal timing does not account for bicyclists in determining the minimum green times or clearance intervals. Like pedestrians, bicyclists need sufficient time to cross an intersection safely. However, this need must be balanced against possible delays for motorist traffic. Accurate estimates of crossing times for bicyclists are thus essential to the safe and efficient design of traffic signals. This paper presents data on bicycle crossing times for different crossing distances near the campus of the University of California at Davis and provides a methodology for measuring bicycle crossing times that other researchers can use. The crossing time and speed data collected for this project can be used to develop guidelines, in conjunction with AASHTO equations, for estimation of minimum green times and clearance intervals as a function of crossing distance. Ten signalized intersections with various motorist and bicycle traffic volumes were videotaped for a total of approximately 11 h. The observed crossing times and calculated speeds for standing, rolling, and quasi-rolling starts are presented. The importance of the physical design of intersections is briefly discussed. Important findings are that the crossing times vary widely for each crossing distance and that the 2nd and 15th percentile speeds are considerably slower than the speeds suggested by AASHTO. These slower speeds may suggest that longer crossing times should be used in signal design to ensure that 98%, or even 85%, of bicyclists will be able to clear an intersection safely.
Development and Application of an International Vehicle Emissions Model
Authors: Davis Nicole , Lents James , Osses Mauricio , Nikkila Nick , Barth Matthew
Published: May 2018

Rapid vehicle growth in developing nations makes it necessary for these nations to address the transportation and environmental impacts of on-road mobile sources. To estimate the air quality impact of their fleets, many nations have adopted modified versions of U.S. or European emissions models or factors. In most cases, these models can lead to significant errors in emissions estimates. To address this problem, a new on-road mobile source emissions model, called the international vehicle emissions (IVE) model, designed for use in developing countries has been developed. The IVE model was developed jointly by researchers at the International Sustainable Systems Research Center and the University of California at Riverside. The IVE model uses local vehicle technology distributions, power-based driving factors, vehicle soak distributions, and meteorological factors to tailor the model to the local situation. In addition, an intensive 2-week field study was designed to collect the necessary fleet and activity data to populate the model with critical local information. The IVE model, along with the field study process, has proved highly effective in providing an improved estimate of mobile source emissions in an urban area and allows the effective analysis of local policy options. The studies have served to transfer tools and knowledge on the process of creating and improving mobile source inventories in an efficient manner. The rationale behind the development of the model, the development and application of the field studies, an overview of the results obtained to date, and planned next steps are described in this paper.
Institutional and Regulatory Options for Bus Rapid Transit in Developing Countries
Authors: Hook Walter
Published: May 2018

An increasing number of cities are looking at bus rapid transit (BRT) as a lower-cost alternative to meeting their mass transit needs. Less fully explored, however, has been the link between BRT and the implementation of transit system regulatory reforms. In a growing number of cities around the world, the introduction of a BRT system has also been used to implement some important long-term transit-sector reforms. Because BRT makes bus operations more profitable, the introduction of BRT gives the municipality additional leverage to demand more from private operators. This paper discusses how, in an increasing number of cities, BRT projects have been used to ( a) facilitate a smooth transition to a sometimes more efficient trunk-and-feeder or hub-and-spoke bus routing system, ( b) increase private-sector investment in the transit system, and ( c) change private bus operating contracts to include quality-of-service requirements.
Pavement Management System Based on Financial Consequence
Authors: Bemanian Sohila , Polish Patty , Maurer Gayle
Published: May 2018

One of the biggest challenges for any public organization is how to prioritize projects to maximize existing funding. With so many programs competing for the same funding, it is especially important to optimize pavement rehabilitation programs to allow for funding for other programs, such as safety, capacity improvements, and environmental improvement projects. This report describes how the Nevada Department of Transportation (NDOT) optimized its available funding while improving pavement condition by using an eight-step pavement management system based on financial consequence. This eight-step procedure includes administration support, contract database implementation, roadway system division, performance models, project prioritization, and strategy selection. This procedure can easily be adopted by other states. A nominal amount of information is required to initiate this system, and the reward can be exceptional. NDOT saves $42 million a year with this methodology. An advantage of a pavement management system based on financial consequence over a conventional network optimization system is that process allows engineers to communicate with top administrators in a nontechnical way. Administrators can understand the concept and make good roadway funding choices without needing a great deal of technical input from engineers. For example, administrators see that the cost of delaying a 10-mi roadway section on an Interstate system by 2 years can cost the agency an additional $6 million for rehabilitation; but that delaying a 10-mi roadway section on a relatively low-volume road can cost only a few thousand dollars.
Wavelet-Based Pavement Distress Classification
Authors: Zhou Jian , Huang Peisen , Chiang Fu-Pen
Published: May 2018

A two-step method–-wavelet transform followed by Radon transform–- is proposed for pavement distress classification. First, a pavement image is decomposed into different frequency subbands by wavelet transform. Distress is transformed into the high-amplitude wavelet coefficients, which are referred to as the details, in the high-frequency subbands. The wavelet modulus is calculated by combining the horizontal, vertical, and diagonal details. Since distress, especially crack, has dominant orientations in both the space domain and the wavelet domain, Radon transform is then applied to the wavelet modulus to transform cracks into peaks in the Radon domain. The patterns and parameters of the peaks are finally used for distress classification. Both simulated and experimental results demonstrate that the proposed two-step method is an effective method for pavement distress classification.
Effect of Fuel Economy on Automobile Safety
Authors: Ahmad Sanjana , Greene David L.
Published: May 2018

Since 1975, the fuel economy of passenger cars and light trucks has been regulated by the corporate average fuel economy (CAFE) standards, established during the energy crises of the 1970s. Calls to increase fuel economy are usually met by a fierce debate on the effectiveness of the CAFE standards and their impact on highway safety. A seminal study of the link between CAFE and traffic fatalities was published by R. W. Crandall and J. D. Graham in 1989. They linked higher fuel economy levels to decreases in vehicle weight and correlated the decline in new car weight with about a 20% increase in occupant fatalities. The time series available to them, 1947–1981, includes only the first 4 years of fuel economy regulation, but any statistical relationship estimated over such a short period is questionable. This paper reexamines the relationship between U.S. light-duty vehicle fuel economy and highway fatalities from 1966 to 2002. Cointegration analysis reveals that the stationary linear relationships between the average fuel economy of passenger cars and light trucks and highway fatalities are negative: higher miles per gallon is significantly correlated with fewer fatalities. Log–log models are not stable and tend to produce statistically insignificant (negative) relationships between fuel economy and traffic fatalities. These results do not definitively establish a negative relationship between light-duty vehicle fuel economy and highway fatalities; instead they demonstrate that national aggregate statistics cannot support the assertion that increased fuel economy has led to increased traffic fatalities.
Surprises from a Field Validation of Speed Estimation Techniques for Air Quality Conformity Analysis
Authors: Miller John S. , Fitch G. Michael , Dougald Lance E. , Kreissler Scott R. , Hill David H.
Published: May 2018

The air quality conformity process requires travel speed estimation for a horizon year, where often few roadway characteristics are precisely known. This paper presents the results of a study to validate three relatively common speed estimation techniques comparing predicted speeds with speeds measured on specific roadway links and illustrates how disparity in speed predictions affect nitrogen oxide (NOx) and volatile organic compound (VOC) estimates in the MOBILE6 emissions model. The results are intriguing. On average, the mean absolute errors for the three techniques were similar, ranging between 8 and 12 mph. This large error resulted because free-flow speed and capacity from the long-range model were not always representative of the links being studied. Further, the study suggests that the error associated with any of the techniques could be reduced to 4 mph through judicious altering of the default capacity or default free-flow speed for a given class of links, a feasible approach even for large networks. Finally, MOBILE6 testing with Virginia metropolitan data suggests that the differences in speed predictions yield a 2.5% difference in estimated VOC emissions, with one technique overestimating VOC emissions by 1.75% and two underestimating VOC emissions by 0.71%. All three techniques underestimated metropolitan area NOx emissions by less than 2%. Because link-based speed validation efforts are relatively rare within the conformity analysis process, the methodology discussed here should be of interest to smaller metropolitan planning organizations seeking to verify that accurate speeds are used in conformity determination.
Analysis of 11 Bioengineered Stream Bank Erosion Control Structures in Alaska
Authors: Karle Kenneth F. , Emmett William W. , Moore Nancy
Published: May 2018

This paper reports the results of a study of the use of bioengineered erosion control structures on Alaskan streams and rivers. Field investigations of hydraulic and vegetation conditions at 11 study sites around the state of Alaska were conducted to determine the performance of these structures. Root wads, live staking, brush layering, and coir logs were the primary bioengineering methods used for erosion control at the study sites. A one-dimensional numerical computer model was applied at each site to estimate the magnitude of average bed and bank shear stresses (tractive force) apparent to the erosion control structures at the 50- and 100-year design flood levels. Discharge records and field flood indicators were checked to correlate structure condition to flow history. Damage at existing structures was attributed to flowing ice, undermining of toe protection, buoyancy effects, and failure of construction fabrics. Root wad structures in good condition were located in areas with high boat wake occurrence but low channel tractive forces. The findings of the study suggest that the types of bioengineered erosion control structures studied have not been proven to offer reliable bank erosion protection during flooding conditions on channels with high tractive forces.
Comparison of Traffic Noise Model 2.5 with 2.1 and Measured Data
Authors: El-Aassar A. A. , Wayson R. L. , MacDonald J. M.
Published: May 2018

Traffic Noise Model Version 2.5 (TNM 2.5) will soon be the official traffic noise model required by the FHWA for federally funded projects. TNM was updated from Version 2.1 to 2.5 to address two major issues: the overprediction found in the previous version of TNM and an anomaly related to diffraction points. This research focused on comparing the TNM 2.5 predicted results with TNM 2.1 predicted values and with measured data from 18 barrier locations in Florida. Matched pairs of predicted and measured differences between the data for TNM 2.5 and TNM 2.1 were evaluated and a direct comparison of the two models was made. This research demonstrated that the predicted results from TNM 2.5 had an average error for all 18 barrier locations of less than 1 dB. However, when each of the sites is evaluated individually, TNM 2.5 has a tendency to underpredict slightly at many of the evaluated barrier locations. Finally, TNM 2.5-predicted results tend to be about 3 dB(A) on average less than TNM 2.1 at a defined reference measurement position, which is relatively unaffected by ground effects or diffraction, and about 1 dB less at microphone positions behind evaluated barriers when compared with TNM 2.1.
Trade-Offs between Security and Inspection Capacity
Authors: Villegas Hilma , Gurian Patrick L. , Heyman Josiah M. , Mata Adrian , Falcone Robert , Ostapowicz Edward , Wilrigs Steven , Petragnani Michael , Eisele Eric
Published: May 2018

Observations of primary inspections at land border ports of entry between Ciudad Juarez, Mexico, and El Paso, Texas, indicate that the majority of inspections are of limited duration and detail. Three policy options are considered for allowing more thorough primary inspections. The first would require all primary inspections to involve opening a vehicle compartment. This would increase average inspection times from 34 s to 70 s. The second option would limit the time in primary inspections to 63 s. Vehicles requiring more time to complete the inspection process would be referred to secondary inspections, which would greatly increase the frequency of referrals to secondary inspections but would allow for the percentage of primary inspections that involve physical inspection of at least one vehicle compartment to be increased to 35%. The third option would increase the number of crossers in the Secure Electronic Network for Travelers Rapid Inspection (SENTRI) program, in which prescreened participants are subject to expedited inspections. Reducing the volume in the non-SENTRI lanes would allow more detailed inspections in these lanes. A doubling of the current SENTRI program would be required to raise the average non-SENTRI, primary inspection time from 34 to 40 s. This study concludes that none of these options, whether alone or in combination, has the potential to avoid conflicts between national security requirements that favor more detailed inspections and local traffic flow consideration that favor less detailed inspections. These strategies are amenable to incremental implementation, however, and such incremental implementation may increase the thoroughness of the inspection process without interfering with local traffic flows.
Preliminary Assessment of Activity Analysis and Modeling for Homeland Security Applications
Authors: Henson Kriste M. , Goulias Konstadinos G.
Published: May 2018

A review of 46 activity-based models is conducted and details features that are required for homeland security applications. Two examples of homeland security studies are included to highlight these needs. This review demonstrates that only a few models have the desired characteristics of fine spatial and temporal resolutions. Because the criticality of locations varies because of time or day of the week or both, depending on the presence of individuals and the fact that potential targets are specific locations within a city, data needs for modeling these types of scenarios exceed typical planning and forecasting modeling as well as research modeling. A discussion of a homeland security–related modeling application conducted by Los Alamos National Laboratory using TRANSIMS for the U.S. Department of Homeland Security is included to demonstrate the level of detail that is achieved by using nationally available data sources. In addition, the literature contains many data and information gaps, including virtually nonexistent models of security; identifying and inventorying residential locations; including more time constraints in models; modeling short-term changes in land use; carefully identifying and filling in missing subpopulations in surveys; accounting for fleets, services, and goods in models; better modeling of inter- and intrahousehold interactions, including weekly and seasonal variations in travel behavior; and developing a new paradigm for activity scheduling in panic and emergency situations.
Exposure of Soil and Groundwater to Spills of Hazardous Materials Transported by Rail
Authors: Anand Pooja , Barkan Christopher P. L.
Published: May 2018

The environmental impact of a hazardous material spill is a complex function of the material's physical and chemical characteristics and the local environmental conditions in which it is spilled. This study develops a geographical probability distribution for two important environmental parameters affecting this impact: soil type and groundwater depth. The paper assesses the probability of exposure of various soil types and groundwater depth regions to hazardous material spills from railroad tank car accidents. The State Soil Geographic database (STATSGO), a geographic information system (GIS) database from the U.S. Department of Agriculture, was used to analyze soils, and real-time groundwater data from the U.S. Geological Survey were used to analyze groundwater. The “rail2m” GIS database available from the Bureau of Transportation Statistics was used to conduct overlay analyses with the soil GIS data to obtain the probability of occurrence of various soil types under rail lines. The same method could not be used for groundwater exposure because no suitable GIS database for this parameter was available. Therefore, a nationwide probability distribution of the groundwater depth ranges was developed. The proportion of the three soil types under rail lines was 44.0% for sand, 51.2% for silt, and 4.0% for clay, the remainder being over surface water. The probability of occurrence of five groundwater depth regions was 16.4% for 5 to 15 ft, 12.6% for 15 to 25 ft, 23.3% for 25 to 75 ft, 12.0% for 75 to 125 ft, and 35.9% for greater than 125 ft. A matrix of the probability distribution of environmental scenarios was developed; it is suitable for use in conducting environmental risk assessments of railroad transportation of hazardous materials.
Case Study of a Survivability Analysis of a Small Intelligent Transportation System
Authors: Benke Matthew , Abdel-Rahim Ahmed , Oman Paul , Johnson Brian
Published: May 2018

With the rapid implementation of intelligent transportation systems throughout the nation, the surface transportation system has become dependent on an extensive network of communication and computing devices. It is no longer sufficient to consider the analysis of the transportation network, its communication infrastructure, and its power supply in separation. Given the increased threats to surface transportation networks, it is imperative that such systems be designed not only for safety and efficiency but also for survivability. A case study to assess the survivability of a small urban transportation system is presented. Two different survivability assessment techniques are presented and applied. The first approach provides a qualitative assessment and is based on a survivable systems analysis modified for critical infrastructures. The second technique provides a quantitative assessment of network survivability using a multilayered graph-based approach. Three layers of critical infrastructure in a transportation system are analyzed: power, information, and physical. Interactions within layers and between layers are identified, and the relative criticality of each component in the three layers is quantified as to the component's essentiality to network performance. The analysis provides a simple means of assessing the importance of different components in critical infrastructure layers, allowing decision makers to prioritize threat mitigation alternatives.
Detection of Invalid Loop Detector Data in Urban Areas
Authors: Weijermars W. A. M. , Van Berkum E. C.
Published: May 2018

Urban traffic data can be used for purposes besides actuated signal control. However, it is important for the data to be of sufficient quality. This paper discusses a procedure for detecting invalid traffic data produced by single-loop detectors at signalized intersections. Basic quality checks—based on minimum and maximum flow thresholds—are used to detect erroneous data, whereas quality checks based on the principle of conservation of vehicles are introduced to detect inaccurate data. In most cases, the principle of conservation of vehicles implies that flow measurements have to be consistent between upstream and monitoring detectors within one intersection. The basic quality checks are appropriate for detecting erroneous data. Moreover, quality checks based on the principle of conservation of vehicles are a useful addition to basic quality checks, because they are appropriate for detecting inaccurate traffic data not detected by the basic quality checks. However, because flows are inconsistent between upstream detectors mutually in some cases, it is not always clear whether the results of this quality check are reliable. These cases were analyzed further by field observations. Finally, because the designed control procedure detects more invalid data than the detector station, it can be concluded that these macroscopic quality checks are a useful addition to the microscopic quality checks.
Quantification of Risk Cost Associated with Short-Term Warranty-Based Specifications for Pavements
Authors: Zhang Zhanmin , Damnjanovic Ivan
Published: May 2018

To reduce overall costs and improve quality, many state highway agencies have begun investigating innovative contracting methods. One of the most important types of such innovative methods is warranty-based contracting. This method is tailored to shift performance-related risk from the agency to the contractor by means of warranty provision. Although the application of the warranty-based contracting method allows for a win–win situation in which agencies hedge the performance-related risk and contractors have more flexibility in design and construction process, there are many concerns about its implementation. One of the most important concerns is quantification of risk cost. A methodological framework was developed to quantify the risk cost, and decision-support models that can be used to analyze short-term performance warranties were formulated. The proposed methodology considers the characterization of the warranty system, the development of a structural reliability performance model based on the method of moments, and the formulation of two decision-support models: the risk cost model and the optimal warranty-based design model. To illustrate the methodology, the development of the proposed decision-support models is presented, along with the current AASHTO design method for flexible pavements, followed by a numerical example that demonstrates the results.
Rational Estimation of Construction Impact on Pavement Performance
Authors: Haggerty Brett , Abdallah Imad , Nazarian Soheil
Published: May 2018

The goal in any highway construction project is to produce a durable pavement that will perform satisfactorily throughout its expected design life. The quality of construction also plays a significant role in accurately predicting the life-cycle performance. In that context, the quality of construction is defined as meeting a structural-related target variable with minimal variance. The implementation of effective performance-based construction quality management requires a tool for determining impact of construction quality on the life-cycle performance of pavements. This process should carefully consider that relevant parameters are different for different types of pavements. What is not so obvious is that for the same type of pavement, the relevant parameters change with the relative structure of the pavement. Many parameters that are important for a thick pavement designed for an Interstate highway may be of secondary significance to a secondary road. Simply put, defining one set of parameters that can be used in all projects is not appropriate because it may not be cost-effective. A statistical-based algorithm is presented; it was developed to reconcile the results from several pavement performance models used in the state of practice with systematic process control techniques. These algorithms identify project-specific parameters that should be the focus of the construction quality management by quantifying the variability of the construction parameters. The identification of these parameters allows for transportation agencies to focus their limited funds and resources more efficiently while increasing the life of the pavement.
Comparative Analysis of Field Permeability Testing of Compacted Hot-Mix Asphalt Pavements
Authors: Menard Jacques , Crovetti James A.
Published: May 2018

The in-place permeability of asphalt pavements has been the focus of recent research as investigators try to establish links between pavement permeability and performance. Previous research concluded that pavements with in-place air voids exceeding 8% to 10% may be considered as excessively permeable, and it is generally accepted that excessively permeable pavements are more prone to oxidation and stripping of the asphalt binder, as well as more susceptible to freeze–thaw degradation. As the use of the Superpave® design procedures has increased, numerous questions have arisen regarding the effect of certain mix design parameters on the in-place density and permeability of compacted asphalt pavements. A recent investigation into this issue has generated the need for reliable test methods and equipment that can be used to assess the field permeability of in-place pavements. Results of field permeability tests conducted on newly constructed asphalt pavements by using both water and air permeameters are presented. The data obtained indicate that currently accepted test methods based on the water permeameter may not produce repeatable results for all pavement types investigated. In contrast, test data obtained with the air permeameter indicate good repeatability for all included pavement types.
Experimental Investigation of Effects of Dowel Misalignment on Joint Opening Behavior in Rigid Pavements
Authors: Prabhu Milind , Buch Neeraj , Varma Amit H. , Thandaveswara Deepa
Published: May 2018

Experimental investigations were conducted to determine the fundamental joint opening behavior of concrete pavements and to evaluate the effects of dowel misalignment on this behavior. The parameters included in the experimental investigations were the number of dowel bars (one, two, three, or five) at the joint, the dowel misalignment type (horizontal, vertical, or combined), misalignment magnitude (0, 1/36, 1/18, 1/12, 1/9 rad), and uniformity across the joint. The effects of these parameters were evaluated for the joint opening behavior and structural distresses observed in the specimens. Forty-seven instrumented laboratory-scale specimens of pavement slabs with doweled joints were tested. The experimental results include the load per dowel–joint opening behavior and observations of structural distress. These results indicate that ( a) all pavement joints are initially locked, and opening displacements occur after the load per dowel exceeds 5 to 7 kN or the average bond shear stress exceeds 0.22 to 0.30 MPa; ( b) for all misalignment types, the load per dowel increases with larger misalignment magnitudes and nonuniformity; ( c) structural distress in the form of concrete spalling and transverse cracking was observed for specimens with larger dowel misalignments and nonuniformity; and ( d) severity of structural distress increased with the number of misaligned dowels at the joint. These experimental results do not provide comprehensive knowledge regarding the mechanics of dowel–concrete interaction, and analytical investigations are needed to address this limitation.
Evaluation of Pavement Slab Rocking and Pumping with Elevation Profile Data
Authors: Byrum Christopher R.
Published: May 2018

A method is presented for estimating the amount of slab rocking and the amount of earth moved beneath a jointed concrete pavement as a result of slab rocking. The estimates are obtained with data from noncontact rapidly traveling profilers that collect surface elevation profiles along roadways at normal driving speeds without lane closure or traffic control costs. With profile data from FHWA Long-Term Pavement Performance (LTPP) General Pavement Study 3 (GPS-3) test sites, examples are provided to show how the apparent slab rocking and pumping volumes develop over time for most GPS-3 test sections that have shown significant faulting. The calculated pumping volume rate per equivalent single-axle load (ESAL) is shown to be relatively constant over time at these LTPP test sites. A preliminary linear regression predictive model for pumping rate per ESAL as a function of pavement design parameters is provided based on the test group of faulting GPS-3 pavements. This study indicates that pumping rate can be reduced with thicker and longer slabs and thicker layers of erosion-resistant base and subbase overlying erosion-susceptible subgrades. Slab lengths less than 15 ft (4.57 m) long appear noticeably more susceptible to rocking and pumping. Sites with high pumping rates typically have a combination of unusually large slabs locked in upward curvature and erosion-susceptible cross-section designs.
Improving Prediction Accuracy in Mechanistic–Empirical Pavement Design Guide
Authors: Schram Scott , Abdelrahman Magdy
Published: May 2018

Model calibration plays a fundamental role in the implementation of the mechanistic–empirical pavement design guide. The data used in the default calibration effort, which were afforded by the Long Term Pavement Performance (LTPP) database, have a network-level inference space. As implementation proceeds, state highway agencies may be inclined to calibrate at a local network level. However, with a focus on the calibration data set to local project-level conditions, model prediction error can be reduced further. Under this study, Nebraska Department of Roads Pavement Management System data were used to calibrate two design guide smoothness models at the local project level. The focused data set was categorized by annual daily truck traffic and surface layer thickness. Results showed that project-level calibrations reduced default model prediction error by nearly twice that of network-level calibration. This study offers a window into the accuracy that can be achieved with local focus calibrations of design guide prediction models.