bluuebunny/crossref_metadata_2025 huggingface dataset:
Investor Perceptions of Potential IFRS Adoption in the United States
Authors: Joos Philip P. M. , Leung Edith
Published: October 2012

This paper examines the stock market reaction to 15 events relating to IFRS adoption in the United States. The goal is to assess whether investors perceive the switch to IFRS as beneficial or costly. Our findings suggest that investors' reaction to IFRS adoption is more positive in cases where IFRS is expected to lead to convergence benefits. Our results also indicate a less positive market reaction for firms with higher litigation risk, which is consistent with investors' concerns about greater discretion and less implementation guidance under IFRS for these firms. Overall, the findings are relevant to the current debate on IFRS adoption in the U.S. and highlight the importance of convergence to investors.

Data Availability:  All data are publicly available from the sources indicated in the paper (see Appendices A and B).
Selecting Audit Samples Using Benford's Law
Authors: da Silva Carlos Gomes , Carreira Pedro M. R.
Published: October 2012

We contribute to digital analysis by developing two mathematical programming models that can assist auditors in selecting more promising audit samples, using Benford's law. One model identifies the smallest subset of nonconforming records in a dataset, given some predefined conformity criteria, and the other highlights the k most nonconforming records. The models take into account several conformity tests and test statistics simultaneously. The application of the models is illustrated using suggested protocols on a set of simulated data. Finally, the effectiveness of the models in detecting typical data manipulations is assessed under different contamination levels.
The Association between Top Management Involvement and Compensation and Information Security Breaches
Authors: Kwon Juhee , Ulmer Jackie Rees , Wang Tawei
Published: October 2012

This paper examines how an information technology (IT) executive's position in a top management team and how his/her compensation are associated with the likelihood of information security breaches. Using a sample drawn from multiple sources in the period from 2003 to 2008, we show that an IT executive's involvement in the top management team is negatively related to the possibility of information security breaches. We also find that the amount of behavior-based (i.e., salary) compensation and the pay differences of outcome-based (i.e., bonuses, stock awards, and stock options) compensation between IT and non-IT executives are negatively associated with the likelihood of information security breaches. Our findings shed light on how an IT executive's status in the top management team and the composition of his/her compensation can be related to a firm's IT governance mechanisms.
Exposure to environmental and lifestyle factors and attention-deficit / hyperactivity disorder in children — A review of epidemiological studies
Authors: Polańska Kinga , Jurewicz Joanna , Hanke Wojciech
Published: October 2012

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in children. Although the mechanisms that lead to the development of ADHD remain unclear, genetic and environmental factors have been implicated. These include heavy metals and chemical exposures, nutritional and lifestyle/psychosocial factors. The aim of this review was to investigate the association between ADHD or ADHD-related symptoms and widespread environmental factors such as phthalates, bisphenol A (BPA), tobacco smoke, polycyclic aromatic hydrocarbons (PAHs), polyfluoroalkyl chemicals (PFCs) and alcohol. Medline, PubMed and Ebsco search was performed to identify the studies which analyze the association of prenatal and postnatal child exposure to environmental toxicants and lifestyle factors and ADHD or ADHD-related symptoms. The review is restricted to human studies published since 2000 in English in peer reviewed journals. Despite much research has been done on the association between environmental risk factors and ADHD or ADHD symptoms, results are not consistent. Most studies in this field, focused on exposure to tobacco smoke, found an association between that exposure and ADHD and ADHD symptoms. On the other hand, the impact of phthalates, BPA, PFCs, PAHs and alcohol is less frequently investigated and does not allow a firm conclusion regarding the association with the outcomes of interest.
The Move over Law
Authors: Carrick Grady , Washburn Scott
Published: October 2012

Police traffic enforcement is a common, recognizable part of the driving environment. As with those in other professions working near roadways, officers are at increased danger when they have stopped on the shoulder. Statistics from the Federal Bureau of Investigation indicate that from 2000 to 2009, 47 U.S. officers were killed while performing traffic stops and 73 were killed while directing traffic or assisting motorists; 101 officers were killed feloniously while conducting traffic stops. To mitigate dangers, every state except Hawaii has implemented a law requiring drivers to move over or slow down when approaching a patrol vehicle stopped at roadside. This research observed the behavior of more than 9,000 right-lane vehicles passing staged police stops on Florida freeways in north and central Florida. Each staged stop involved the use of a civilian research vehicle, a marked police vehicle, video recording of passing traffic, and measurement of passing vehicle speeds with a laser speed measurement device. Overall compliance with the move over component of the Florida laws was 75.9%, but compliance with the legal requirement to slow to 20 mph below the speed limit when not moving over was just 5.8%. Examination of patrol vehicle emergency lighting configurations determined that the use of blue and red emergency lights increased compliance in a statistically significant way, to nearly 80%, versus 68.8% when only amber lights were used. Additionally, when blue and red lights were not used, driver merge maneuvers were executed closer to the stop, and mean speeds of non–move over vehicles were higher.
Spatial Effectiveness of Speed Feedback Signs
Authors: Santiago-Chaparro Kelvin R. , Chitturi Madhav , Bill Andrea , Noyce David A.
Published: October 2012

Speed feedback signs (SFS), also known as dynamic speed displays, provide drivers with feedback about their speed in relationship to the posted speed limit. When appropriately complemented with police enforcement, SFS can be an effective method for reducing speeds at a desired location. However, as reported in the literature, effectiveness of SFS is limited not only in regard to time after the deployment but also for distance. Therefore, a need exists to understand how far upstream and downstream of the SFS speed reductions are maintained. Through a unique data collection methodology, researchers obtained trajectories of free-flowing vehicles that approached an SFS, as well as trajectories of vehicles receding from the SFS. Trajectory data were used by researchers to determine the locations at which drivers willing to reduce their speed when approaching the SFS actually started the reduction. Downstream of the SFS, the distance at which drivers started increasing their speed after complying with the sign was also determined. Results showed the feasibility of determining the spatial effectiveness of SFS. By using the methods as presented, speed enforcement personnel can understand how drivers in an area of interest react to SFS and therefore can determine the best locations for SFS as well as the number of SFS that need to be deployed to achieve a speed reduction over a segment of road.
Actual and Perceived Risks of Apprehension for Speeding in Norway
Authors: Elvik Rune
Published: October 2012

A study on the actual and perceived risks of apprehension for speeding in Norway was conducted. The actual risk of apprehension was estimated by combining data on the speed of traffic and data on the number of citations for speeding. The risk of apprehension for minor violations was zero, which showed that both police officers and speed cameras allowed a safety margin before citing a driver for speeding. There was a dose-response relationship between the level of speeding and the risk of apprehension: the more severe the violation, the higher the risk of apprehension was. In general, however, the risk of apprehension for speeding was low and tended to be overestimated by drivers.
Sensitivity Study of Jordan Rollover System and Unconstrained Model
Authors: Tahan Fadi , Yan Lingbo , Digges Kennerly
Published: October 2012

Finite element analysis was used to compare the dynamic rollover performance of a midsized sport utility vehicle with a strengthened roof in a Jordan Rollover System (JRS) test with an unconstrained rollover under the same initial conditions. The JRS can control closely the initial conditions of a vehicle being subjected to a rollover test. This research was proposed to study the ability of the JRS to emulate the vehicle kinematics and roof crush resulting from an actual rollover. An additional sensitivity study for the test bed mass and yaw angle was performed. The model was given initial conditions at impact similar to the JRS common values. These conditions were a roll angle of 145°, a pitch angle of 5°, a yaw angle of 10°, a test bed speed of 24 km/h, a vertical drop height of 10 cm, and a roll velocity of 190°/s. The finite element model of a 2003 Ford Explorer was used in this study and was validated against several full-scale tests. Then the roof was strengthened to meet the new federal roof regulation. Computer simulations comparing a JRS test with an unconstrained rollover showed that during a pure roof crush phase, both models behaved similarly. Afterward, some variations occurred, but the differences were less than 5%. For different test bed mass, the only significant difference between the model results was the final test bed speed. Finally, increasing the yaw angle in a JRS test showed a decrease in roll rate and intrusion characteristics of less than 5%.
Describing Non–Lane-Based Motorcycle Movements in Motorcycle-Only Traffic Flow
Authors: Nguyen Long Xuan , Hanaoka Shinya , Kawasaki Tomoya
Published: October 2012

The motorcycle is the main transport mode for commuters in Vietnam because it costs less than a car and has greater mobility on congested city roads. A better understanding of the characteristics of motorcycle traffic flow can be helpful in formulating proposals for traffic management policies. Under congested conditions, motorcycles are observed to change their directions and speeds quite often. This study focuses on the zigzag movements of motorcycles in motorcycle-only traffic, which are termed “non–lane-based movements.” Research was conducted on the mechanisms of non–lane-based movements with a consideration of how two behaviors of a subject motorcycle—acceleration and deceleration—were affected by the velocity changes of lead motorcycles. A concept of safety space was introduced to explain these behaviors. Calibration data for the proposed model were extracted from video clips taken at road segments in Ho Chi Minh City, Vietnam. By calculating the root mean square error of the estimated value and the field value, the proposed model reproduced the speed and direction of motorcycles with high reliability. A computer simulation was used to reproduce two basic types of non–lane-based movements—oblique following and swerving—and to verify the difference in the speed–flow relationship between lane-based and non–lane-based movements.
Characteristics of Injuries in Motorcycle-to-Barrier Collisions in Maryland
Authors: Daniello Allison , Gabler Hampton C.
Published: October 2012

Motorcycle-to-barrier collisions are more serious than many other motorcycle crash modes, such as collisions with only the ground or passenger cars. To identify the potential need for design improvements to traffic barriers to reduce the severity of these crashes, the injuries incurred during these collisions must first be understood better. The objective of the study was to determine the type, relative frequency, and severity of injuries incurred in motorcycle-to-barrier crashes in Maryland. The Crash Outcome Data Evaluation System (CODES) was used to analyze motorcycle crashes in Maryland from 2006 to 2008. CODES links police-reported crashes to hospital data, providing detailed information about injuries incurred during collision. This study focused on four crash modes for motorcyclists: single-vehicle barrier collisions, single-vehicle fixed-object collisions, multivehicle collisions, and single-vehicle overturn-only collisions. The most commonly injured body regions for all motorcycle crashes were the upper or lower extremities or both; more than 70% of motorcyclists involved in crashes analyzed suffered an injury to the upper or lower extremities or both. Motorcyclists involved in barrier collisions were 2.15 (95% CI: 1.17 to 3.92) times more likely to suffer serious injury to the thorax than were motorcyclists involved in overturn-only collisions. Additionally, the risk of rib fracture was increased for barrier and other fixed-object collisions, compared with that of multivehicle collisions. The relative risk of rib fracture compared with risk in multivehicle collisions was 1.99 (95% CI: 1.17 to 3.40) in barrier collisions and 2.32 (95% CI: 1.62 to 3.33) in other fixed-object collisions.
Safety Benefits of Stability Control Systems for Tractor–Semitrailers Estimated with Hardware-in-the-Loop Simulation
Authors: Park Sangjun , Donoughe Kelly , Rakha Hesham A.
Published: October 2012

This research estimated the safety benefits of electronic stability control systems for tractor–semitrailers by using hardware-in-the-loop (HiL) simulation. The HiL system used in this study consisted of a pneumatic tractor–semitrailer braking system and a truck simulation engine, TruckSim. Additionally, the Bendix electronic stability control system was integrated with the HiL system for the evaluation. The study evaluated the performance of the stability control system by using the HiL platform for a portion of the rollover and loss-of-control crashes selected from the database of the Large Truck Crash Causation Study. Subsequently, the evaluated performance was combined with the effectiveness rated by the expert panel at the University of Michigan Transportation Research Institute to calculate the total crash prevention ratios. Finally, this study estimated crash reductions and cost benefits. It provides lessons learned to researchers and practitioners through the course of evaluation procedures.
Wireless Roadside Inspection of Commercial Motor Vehicles
Authors: Cherry Christopher , Bordley Lawson , Petrolino Joseph , Stephens Denny , Kelfer Jonathan
Published: October 2012

The increase in truck mileage each year, with inspection resources remaining relatively constant, has motivated the development of a federal wireless roadside inspection (WRI) program. The WRI program is meant to increase the frequency of inspections substantially with the use of technology to inspect commercial vehicles automatically. In concept, this greater frequency will improve the effectiveness of manual inspections by initially screening compliant drivers, vehicles, and carriers. WRI technology could be voluntary for compliant carriers, to increase credit for positive inspections, and mandatory for noncompliant carriers, to detect major safety problems. Increasing the probability of inspection should act as a deterrent for knowingly noncompliant vehicles and carriers. Quantifiable results of technologies and use scenarios deployed in the FMCSA-and RITA-sponsored pilot test are described. The test was performed in three states (New York, Tennessee, and Kentucky) to evaluate three technology platforms (dedicated short-range communications, commercial mobile radio services, and universal identification). The pilot test will inform, in part, the decision to deploy a national program in the future. This paper also describes the technical results from the 15-week pilot test. Its focus is system performance across all technologies and communication pathways in the context of WRI supporting a number of possible real-time and non–real-time scenarios. During the limited pilot test, few technical barriers supported the real-time and non–real-time scenarios; yet message accuracy and communication speed should be improved in a larger deployment.
Effects of Hours of Service and Driving Patterns on Motor Carrier Crashes
Authors: Jovanis Paul P. , Wu Kun-Feng , Chen Chen
Published: October 2012

There is a need to explore the relationship, if any, between the probability of a crash and the hours worked by truck drivers. The need arises from the continued adjustment of federal hours of service regulations for truck drivers. This research used data logs from less-than-truckload carrier operations in 2004 to 2005 and in 2010 to estimate the probability of a crash after a certain amount of time spent driving, given no crashes until that time. Driver logs for 7 days before each crash were used and compared with a random sample (two drivers) of drivers who did not crash and were selected from the same company, terminal, and month. This study involved 686 subjects, including 224 crash-involved drivers. Discrete-time survival analysis models indicated a consistent increase in crash odds as driving time increased beyond the fourth hour. Breaks from driving reduced crash odds by as much as 50% compared with situations of drivers with no breaks. Crash odds were lowest when drivers returned to work during the day without an immediately preceding extended recovery period (but with at least minimum required off-duty time). Drivers returning to work immediately after a 34-h recovery period had crash odds 50% to 150% higher than those for drivers without the recovery immediately before a trip. Drivers had the highest crash odds immediately after returning from the extended time off; the effect then diminished with time.
Test of Global Positioning System–Inertial Measurement Unit Performance for Surveying Road Alignment
Authors: Lee JunSeok , Yun DukGeun , Sung Junggon
Published: October 2012

In an effort to shift road alignment surveying from manual to automatic methods, moving objects—such as a vehicle on which a Global Positioning System–inertial measurement unit (GPS-IMU) is mounted—are being used to perform surveys and obtain more accurate results. Two road alignment survey methods are compared: an affordably priced microelectromechanical system (MEMS) GPS-IMU and a high-priced fiber-optic–type GPS-IMU. Cross-section angle values from a stationary laser scanner survey and a GPS-IMU survey are compared to determine whether the roll attitude value of GPS-IMU can be used to ensure a more accurate comparison of the cross-section angle. In addition, GPS-IMU performance is compared under various test conditions to survey road alignment, and results indicate that the fiber-optic GPS-IMU is needed to ensure accuracy within the 10% margin of error required for road alignment. In a test conducted to verify whether the roll value of a vehicle can be used as is to survey the cross-section angle of a road, the values from GPS-IMU, drawing, and laser were within a 1% margin of error. Thus, it would be possible to use the roll value obtained from a vehicle as is to survey the road cross-section angle accurately.
Modeling the Structural Response of Urban Subsurface Drainage Systems
Authors: Berthelot Curtis , Soares Roberto , Haichert Rielle , Podborochynski Diana , Guenther Duane , Kelln Roanne
Published: October 2012

In recent years, many City of Saskatoon (COS), Canada, roads have experienced premature failures. High water tables, increased precipitation, and poor surface drainage have caused increased moisture infiltration in road structures. Further deterioration of these aged pavements is attributable to heavy year-round loadings in urban traffic. To address these issues, COS piloted subsurface drainage and strain dissipation layers in some roads. These drainage systems were constructed with crushed portland cement concrete (PCC) rock and conventional virgin crushed rock. Given the empirical nature of conventional road design methods currently used by COS, the structural benefits of drainage systems are difficult to quantify. Therefore, a reliable method that directly incorporates recycled materials, substructure drainage systems, and diverse field conditions is needed. A mechanistic analysis of the drainage systems was piloted in rehabilitated COS pavement structures with a three-dimensional (3-D) nonlinear orthotropic computational road structural model. The 3-D mechanistic model was used to predict peak surface deflections and normal and shear strains in the structure. Modeling results showed that constructing pavement structures with a substructure drainage layer of crushed PCC rock improved the structural performance of the road system in terms of strains under applied traffic loads. The road model provided primary response predictions that correlated with deflections measured by a heavy weight deflectometer, before and after construction. Therefore, the road model used is a reliable pavement engineering analysis tool able to predict the in-field structural behavior of various road structures under diverse field state conditions.
Evaluating the Effect of Natural Gas Developments on Highways
Authors: Banerjee Ambarish , Prozzi Jolanda P. , Prozzi Jorge A.
Published: October 2012

The natural gas reserve in the Barnett Shale geological formation is one of the largest onshore natural gas reserves in the United States. The development of a natural gas well is a traffic-intensive operation that involves high volumes of truck traffic; saltwater traffic generated during the production phase is a major contributor to truck volume. The effect of traffic related to the natural gas industry on Texas highways is quantified. The oversized and overweight database maintained by the Texas Department of Transportation (DOT) was used to quantify several key characteristics of the rig traffic. In addition, personnel from the Texas DOT's Fort Worth District provided critical information about construction and saltwater traffic, including truck types used, gross vehicular weights, number of trips, and haul distances. Pavement sections were located along the busiest trucking corridors to evaluate damage caused by the truck traffic associated with natural gas development. Results indicated the approximate damage due to rig traffic was 1.6%, to construction traffic was 13%, and to saltwater traffic was 6%, relative to the damage caused by design traffic in terms of rutting. Additional damage caused by the natural gas truck traffic translated into reduced service life for pavements in the region. Results indicated a reduced service life of approximately 5.6%, 29%, and 16% associated with rig, construction, and saltwater traffic, respectively, in terms of rutting.
Procedure for Making Paving Decisions with Cluster and Multicriteria Analysis
Authors: Dell'Acqua Gianluca , De Luca Mario , Russo Francesca
Published: October 2012

For many years, much research has been carried out to assess the affordability of paving a road. Now, increased construction and maintenance costs for traditional asphalt pavement systems have persuaded many civil administrations, regional councils, and agencies to replace pavement with gravel surfaces. Low-volume roads (LVRs), as they are presented in this paper, constitute a significant proportion of the total road network in Italy (around 80%) and in many other countries. Such infrastructures are vital parts of the road network, but their construction can have significant adverse effects on the environment. As a result, these roads must be well planned, well designed, well constructed, and properly maintained to create minimal adverse effects, to be cost-effective in the long term, and to have acceptable maintenance and repair costs. Limited resources often exist for LVRs, and a frequent question is whether to use paved or gravel surfaces. In many cases, the choice depends only on economic considerations, which must take maintenance costs into account. A complete procedure that applies cluster analysis and multicriteria analysis is presented for deciding whether to pave gravel road surfaces on the basis of different geometric, traffic, and environmental layouts.
Three-Dimensional Methodology for Design of Safe Rural Highways
Authors: Kuhn Wolfgang , Leithoff Ingolf , Kubik Ronny
Published: October 2012

The planning and design process for rural roads in Germany takes place iteratively, in multiple design stages, with each followed by an approval procedure. However, design engineers lack adequate aids for the real technical design work (e.g., route search, option comparisons, and safety checks). Therefore, a design methodology is being developed in Germany as part of a research project in which a new model concept—three-dimensional (3-D) route search—is being used. The 3-D route is created by superimposing the classic design elements from horizontal and vertical projections. After the 3-D route is broken down into the individual design levels, two-stage safety checks follow according to geometric criteria (guideline specifications) and expected driving behavior (driving simulation). Various visualization techniques (e.g., two-dimensional or 3-D display, driving simulation in the virtual driving area) support design engineers in the interactive planning and checking process. The new workstation that has been developed combines design methodology with hardware and software components and therefore handles the overall process of designing, checking, driving, and assessing in a practical manner.
Sensitivity Analysis of Combined Distribution–Assignment Model with Applications
Authors: Du Muqing , Cheng Lin , Rakha Hesham
Published: October 2012

The equilibrium trip distribution–assignment model with variable destination costs (ETDA-VDC) is critical for the modeling of evacuation strategies that consider transportation network capacity. The model is an improvement over the combined distribution–assignment model because it integrates the destination cost function. With mild requirements, a rectified restriction approach was developed to generate a restricted equilibrium problem, in which the applicability of the implicit function theorem was proved. Explicit expressions of the derivatives of model variables for perturbations of input variables and parameters of the ETDA-VDC model were derived. The results of a simple numerical example were used to demonstrate four applications: sensitivity-based algorithm for the bilevel network capacity model, analysis of paradox, identification of critical parameters, and access control. The usefulness and importance of the sensitivity expressions were also demonstrated.
Hyperpaths in Network Based on Transit Schedules
Authors: Noh Hyunsoo , Hickman Mark , Khani Alireza
Published: October 2012

The concept of a hyperpath was introduced for handling passenger strategies in route choice behavior for public transit, especially in a frequency-based transit service environment. This model for handling route choice behavior has been widely used for planning transit services, and hyperpaths are now applied in areas beyond public transit. A hyperpath representing more specific passenger behaviors on a network based on transit schedules is proposed. A link-based time-expanded (LBTE) network for transit schedules is introduced; in the network each link represents a scheduled vehicle trip (or trip segment) with departure time and travel time (or arrival time) between two consecutive stops. The proposed LBTE network reduces the effort to build a network based on transit schedules because the network is expanded with scheduled links. A link-based representation of a hypergraph with existing hyperpath model properties that is directly integrated with the LBTE network is also proposed. Transit passenger behavior was incorporated for transfers in the link-based hyperpath. The efficiency of the proposed hyperpath model was demonstrated. The proposed models were applied on a test network and a real transit network represented by the general specification of Google's transit feed.
Hybrid Artificial Bee Colony Algorithm for Transit Network Design
Authors: Szeto W. Y. , Jiang Yu
Published: October 2012

A hybrid enhanced artificial bee colony algorithm (HEABC) is proposed for solving the problem of bus network design. The algorithm is intended to reduce the weighted sum of the number of transfers and the total travel time of the users through restructured bus routes and new frequencies without increased fleet sizes. The HEABC relies mainly on the enhanced artificial bee colony algorithm to determine the route structure, and the frequency is determined by the frequency-setting heuristic during the fitness evaluation. For an illustration of its performance, the HEABC was compared with a hybrid generic algorithm and a variant of the HEABC. The results indicated that the HEABC could produce better solutions than the other two algorithms could. Moreover, the HEABC could produce a design that was better than the existing design for maximum intermediate stops, total travel time, number of transfers, maximum headway, and total fuel cost. The design should be acceptable to the public and to bus operators.
Estimating Weights of Times and Transfers for Hyperpath Travelers
Authors: Kurauchi Fumitaka , Schmöcker Jan-Dirk , Fonzone Achille , Hemdan Seham Mohamed Hassan , Shimamoto Hiroshi , Bell Michael G. H.
Published: October 2012

In high-frequency transit networks, travelers are often assumed to reduce their travel time by identifying sets of attractive lines. This concept was used in the development of most transit assignment models. Whether transfer penalties and waiting times are more highly valued than onboard travel times largely has been ignored in these assignment models. The literature on the estimation of the value of time for public transport passengers also ignores the complexity of choices faced by transit travelers in large cities. An effort to close this gap addressed the question of whether different passenger groups choose different strategies at stops. A web-based survey was conducted, and data from 597 individuals from various countries were obtained. Hyperpath selection was formulated as a discrete choice model, and the relative weights were estimated. Nested logit models were used to consider the correlation between alternatives within the hyperpath. Results indicated that individual specific attributes significantly influenced passengers' selection of hyperpath.
Evaluation of Resiliency of Transportation Networks after Disasters
Authors: Freckleton Derek , Heaslip Kevin , Louisell William , Collura John
Published: October 2012

The resiliency of infrastructure, particularly as related to transportation networks, is essential to any society. This resiliency is especially vital in the aftermath of disasters. Recent events around the globe, including Hurricane Katrina and significant seismic events in Haiti, Chile, and Japan, have increased the awareness and the importance of resiliency. Transportation systems are key to response and recovery. These systems must withstand stress, maintain baseline service levels, and be stout enough in physical design and operational concept to provide restoration to the system. Analysis of a transportation network's resiliency before a disruptive event will help decision makers identify specific weaknesses within the network so that investments and improvement projects are prioritized appropriately. Previous research in quantification of network resiliency was expanded into a proposed methodology, through which understanding and applying concepts of network resiliency could preclude many devastating effects of destabilizing events and preserve the quality of life and economic stability.
Effect of Pavement Roughness on User Costs
Authors: Islam Shahidul , Buttlar William G.
Published: October 2012

After the construction of a pavement system, deterioration occurs because of traffic loading and weathering action and results in the formation of various types of distresses and an increase in pavement roughness. “Roughness” can be defined as irregularities of pavement surface that affect driver safety and increase user costs, including fuel consumption, repair and maintenance, depreciation, and tire costs. In this study, pavement roughness was predicted with the use of the newly released Mechanistic–Empirical Pavement Design Guide for levels of initial roughness condition. Four alternative maintenance and rehabilitation (M&R) strategies were used to estimate the life-cycle cost of pavement over a 35-year analysis period. Various categories of user costs were calculated on the basis of different cost models and from data reported in the literature. From this analysis, pavement roughness was found to affect user costs dramatically. A comparison was made between agency investment and user costs related to pavement roughness. The results of this analysis showed that agency costs were small compared with roughness-related user costs over the life of the pavement (less than 4% of total costs) and that agency investment in increased rehabilitation activities could have a 50-fold return in the form of reduced user costs. A strong case is made for the critical importance of investing in enhanced M&R activities to reduce pavement roughness. This case is strengthened by hypothesized benefits in pavement system sustainability through reduced user fuel costs and reduced tire wear and increased remaining life of pavement.
Internet Mobility Survey Sampling Biases in Measuring Frequency of Use of Transport Modes
Authors: Diana Marco
Published: October 2012

A quantitative analysis is developed for the biases that arise when trip frequencies for a general population are measured through an online survey instrument. Data from a national official survey in Italy, concerning both mobility behaviors and skills in using computers and the Internet, were deployed to assess differences in mobility levels between those who can answer a computer–Internet survey and those who cannot. Positive correlations were found between ability in using information and communications technologies (ICT) tools and trip frequencies. These latter correlations are about 15% to 150% higher for the ICT literate, according to the travel means under consideration. A Heckman sample selection model showed that these biases have different explanations. People who know how to use the Internet are different from others in their car-driving behavior because of a range of self-related factors. Conversely, public transport patterns of use are more similar between the two groups: the observed bias is mainly because of the fact of using the Internet itself, which could, for example, lead to a more active lifestyle. Such a distinction is of practical interest because it can help to define a method to correct these biases. According to the results of this study, the overestimation of public transport frequency of use by an Internet survey could be corrected by looking at the Internet diffusion in the population, whereas corrections for car-driving frequencies are more complex and should be based on differences in attitudinal and personal characteristics between Internet survey respondents and the remainder of the population.
Evaluating the Operational Impact of Left-Turn Waiting Areas at Signalized Intersections in China
Authors: Yang Zhao , Liu Pan , Tian Zong Z. , Wang Wei
Published: October 2012

Transportation professionals in China have started using left-turn waiting areas and lagging left-turn phasing to improve traffic efficiency at signalized intersections. Left-turn waiting areas are usually set up beyond the stop bar at an exclusive left-turn lane or dual left-turn lanes. This design allows left-turning vehicles to enter and wait at the left-turn waiting area after the initiation of the through phase. The operational impact of left-turn waiting areas at signalized intersections was evaluated, and the arrival and departure processes of left-turning vehicles at exclusive left-turn lanes with and without waiting areas were compared. A procedure for estimating the capacity of an exclusive left-turn lane with a waiting area was proposed. Cross-sectional analysis used data collected from 12 approaches at nine signalized intersections to compare the start-up lost time and saturation headways of left-turn passenger cars for four scenarios. The capacities of exclusive left-turn lanes with differently sized left-turn waiting areas were compared. The results indicate that left-turn waiting areas increase the capacity of exclusive left-turn lanes and that the capacity gains would increase with an increase in the storage capacity of the left-turn waiting area.
Equilibrium of Probabilities for Estimating Distribution Function of Critical Gaps at Unsignalized Intersections
Authors: Wu Ning
Published: October 2012

The critical gap is an important parameter for capacity analysis at unsignalized intersections. This parameter is stochastically distributed and cannot be obtained directly by field measurements. Thus, many procedures for estimating the critical gap have been developed. A new model for estimating critical gaps at unsignalized intersections was introduced. The new model used equilibrium of probabilities for rejected and accepted gaps and did not require presumptions regarding the distribution function of critical gaps and driver behavior. This new model has led to an unparameterized empirical distribution of critical gaps. The mathematical function of the critical gaps was not required in advance. A solution is presented to account for predefined distribution functions of critical gaps. Regression analysis is used to calibrate two distribution functions—lognormal distribution and Weibull distribution—to the empirical distribution of critical gaps. The Weibull distribution better represents the distribution of critical gaps.
Ensemble Tree Approach to Estimating Work Zone Capacity
Authors: Weng Jinxian , Meng Qiang
Published: October 2012

Accurate estimation of work zone capacity is necessary for successful traffic control management at work zones. This study uses an ensemble tree approach to estimate work zone capacity more accurately than would a model that was based on a single decision tree. A bootstrap aggregation method is used to build an ensemble tree comprising a set of individual decision trees. In this method, a set of bootstrap samples is generated by sampling with replacement from a training sample. A set of individual trees is then constructed with a tree learning algorithm and combined through averaging of the output. Data on work zone capacity from 14 states and cities are used in a case study to build and evaluate the ensemble tree. The results of the statistical comparison demonstrate that the ensemble tree outperforms the existing models of work zone capacity in estimation accuracy. The ensemble tree also performs better than any single decision tree for stability. A comparison with the 2010 Highway Capacity Manual indicates that the ensemble tree can provide a more accurate estimate of work zone capacity. Unlike the manual's model, the ensemble tree avoids estimated errors caused by subjective judgments of users because it does not require manual setting of various adjustment factors. Because of its high estimation accuracy and stability, the ensemble tree is a good alternative for estimating work zone capacity, especially for inexperienced users.
Operational Performance and Speed–Flow Relationships for Basic Managed Lane Segments
Authors: Thomson Timothy , Liu Xiaoyue Cathy , Wang Yinhai , Schroeder Bastian J. , Rouphail Nagui M.
Published: October 2012

Managed lane facilities, including high-occupancy vehicle (HOV) lanes, high-occupancy toll lanes, and express lanes, have become attractive tools for managing today's transportation system. Although managed lanes, specifically, HOV lanes, have existed for several decades, there has been little documentation of their traffic flow behaviors. Because these facilities tend to take on a variety of configurations, including different numbers of managed lanes and separation types from abutting general purpose lanes, transportation engineers should understand the traffic flow differences among facility types. An understanding of the interaction between managed lanes and parallel general purpose lanes is also needed for assessing the performance of managed lanes. A study was done to investigate the performance and traffic flow behavior of managed lane facilities at sites across the country. Traffic flow behavior for five facility types, based on separation type and number of lanes, was analyzed. Factors such as frictional impact on the managed lane—caused by poor performance of the general purpose lanes and slow vehicle effects on managed lane facilities where passing is prohibited—were considered in development of a set of speed–flow curves for each of the five basic facility types. These speed–flow relationships are expressed similarly to basic freeway segments in the Highway Capacity Manual and can be readily incorporated into the manual for predicting the performance of combined general purpose and managed lane facilities.
Calibration and Validation of Highway Capacity Manual 2010 Capacity Model for Single-Lane Roundabouts
Authors: Wei Ting , Grenard Jeromy L.
Published: October 2012

The 2010 edition of the Highway Capacity Manual (HCM 2010) provides new capacity models for single-lane and multilane roundabouts, which generally predict lower capacity than other popular models previously used in the United States. Acknowledging that both roundabout design practices and the public's use of roundabouts are still maturing in the United States, the HCM recommends local calibration of the capacity models to best reflect local behavior and specifies a calibration procedure that uses two gap acceptance parameters: the critical headway and the follow-up headway. This calibration procedure was used in a case study to develop a calibrated HCM model that was based on driver behavior at three single-lane roundabouts in Carmel, Indiana. Both gap acceptance parameters in Carmel were significantly lower than the default values in the HCM 2010. For validation, the calibrated HCM model was compared with the actual 1-min flow rates collected in the field during the congested periods. The calibrated HCM model was consistent with the field conditions for the low to medium circulating flow rates and overestimates the capacity for the high circulating flow rates. Other findings include the impact of exiting traffic, circulating flow rates, degree of saturation, and amount of the gap acceptance data on the calibration results.
Deterministic Approach to Managed Lane Analysis on Freeways in Context of Highway Capacity Manual
Authors: Schroeder Bastian J. , Aghdashi Seyedbehzad , Rouphail Nagui M. , Liu Xiaoyue Cathy , Wang Yinhai
Published: October 2012

The building of managed lanes parallel to general purpose lanes is an increasingly common approach to optimizing freeway capacity. Managed lanes allow agencies to classify customers and assign a portion of the freeway capacity to them. With no methodology in the Highway Capacity Manual (HCM) for analyzing these facilities, analysts rely on more time-consuming simulation analyses. A methodology is presented for estimating the performance of a parallel system of general purpose and managed lane facilities in an HCM context based on NCHRP Project 3–96. The methodology defines new managed lane segment types to use in an HCM analytical framework and is associated with a new set of speed–flow curves. It is sensitive to the number of lanes and the type of separation between managed lanes and general purpose lanes. The method introduces the concept of parallel lane groups of general purpose and managed lanes and thus can account for speed reduction in managed lanes caused by congestion in adjacent general purpose lanes. The method was implemented in a computational engine, FREEVAL-ML, which was built on the freeway facilities method in HCM 2010 but which was updated to incorporate inputs and outputs of the managed lane components. The geometry of two existing managed lane facilities in Washington State is used to illustrate the method, demonstrating the applicability of the analytical framework to real-world facilities.
Occipitotemporal hippocampal depth electrodes in intracranial epilepsy monitoring: safety and utility
Authors: Bekelis Kimon , Desai Atman , Kotlyar Alex , Thadani Vijay , Jobst Barbara C. , Bujarski Krzysztof , Darcey Terrance M. , Roberts David W.
Published: October 2012

Object

Intracranial monitoring for epilepsy has been proven to enhance diagnostic accuracy and provide localizing information for surgical treatment of intractable seizures. The authors investigated the usefulness of hippocampal depth electrodes in the era of more advanced imaging techniques.

Methods

Between 1988 and 2010, 100 patients underwent occipitotemporal hippocampal depth electrode (OHDE) implantation as part of invasive seizure monitoring, and their charts were retrospectively reviewed. The authors' technique involved the stereotactically guided (using the Leksell model G frame) implantation of a 12-contact depth electrode directed along the long axis of the hippocampus, through an occipital twist drill hole.

Results

Of the 100 patients (mean age 35.0 years [range 13–58 years], 51% male) who underwent intracranial investigation, 84 underwent resection of the seizure focus. Magnetic resonance imaging revealed mesial temporal sclerosis (MTS) in 27% of patients, showed abnormal findings without MTS in 55% of patients, and showed normal findings in 18% of patients. One patient developed a small asymptomatic occipital hemorrhage around the electrode tract. The use of OHDEs enabled epilepsy resection in 45.7% of patients who eventually underwent standard or selective temporal lobe resection. The hippocampal formation was spared during surgery because data obtained from the depth electrodes showed no or only secondary involvement in 14% of patients with preoperative temporal localization. The use of OHDEs prevented resections in 12% of patients with radiographic evidence of MTS. Eighty-three percent of patients who underwent resection had Engel Class I (68%) or II (15%) outcome at 2 years of follow-up.

Conclusions

The use of OHDEs for intracranial epilepsy monitoring has a favorable risk profile, and in the authors' experience it proved to be a valuable component of intracranial investigation. The use of OHDEs can provide the sole evidence for resection of some epileptogenic foci and can also result in hippocampal sparing or prevent likely unsuccessful resection in other patients.
Congenital solitary infantile myofibromatosis involving the spinal cord
Authors: Kim Eun Ji , Wang Kyu-Chang , Lee Ji Yeoun , Phi Ji Hoon , Park Sung-Hye , Cheon Jung-Eun , Jang Young Eun , Kim Seung-Ki
Published: October 2012

Infantile myofibromatosis, a rare mesenchymal disorder that develops in early childhood, is classified by the number of lesions that occur: solitary or multicentric. Involvement of the CNS is unusual in either type. Infantile myofibromatosis in the spine is exceptional, and most published cases represent a secondary invasion. Here, the authors report on an 8-month-old girl presenting with weakness below the ankle and an intraspinal mass extending from T-6 to the conus. The patient underwent only partial surgical removal of the lesion, and the pathology was confirmed as infantile myofibromatosis. After the operation, weakness in the lower extremities gradually improved; however, she could not walk at the time of the final follow-up. On follow-up MRI performed 19 months after the operation, the residual lesion remained unchanged with decreased enhancement.