bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Wheel Loads of High-Speed Rail at Speeds Greater than 400 km/h
Authors: Kim Dae Sang , Ham Young Sam
Published: December 2013

The high-speed rail (HSR) line in South Korea has been in service since 2004 with a maximum design speed and operating speed of 350 km/h and 300 km/h, respectively. Recently, South Korea developed a high-speed electric multiple unit (HEMU-430X, 430-km/h eXperiment) with a maximum design speed and operating speed of 430 km/h and 400 km/h, respectively; the government was waiting for a trial run on a conventional HSR line. This study tried to predict wheel load fluctuation (WLF), one of the key factors affecting acceleration to speeds over 400 km/h. For WLFs to be understood accurately in the high-speed range greater than 400 km/h, field running tests were performed twice with the KTX-Sancheon trains on the Gyeongbu high-speed line. The trains traveled between Gwangmyeong and Daejeon at maximum running speeds of 302 and 335 km/h, respectively, and WLFs were measured with a telemetry system (radio data transmitter and receiver system) at varying speeds. On the basis of probabilistic data analysis with a Gaussian function, the WLF (σ/Pst) normalized nondimensional parameter at speeds of 400 km/h and 500 km/h was modeled into quadratic functions. The WLFs at speeds of 400 km/h and 500 km/h were predicted to be 0.356 and 0.512, respectively. In addition, impacts from structures that greatly affected WLFs, such as turnouts, transition zones, and loose sleepers, were evaluated quantitatively. Of those, turnouts had the greatest impacts on the WLFs.
Predicting Potential Railway Operational Disruptions with Echo State Networks
Authors: Fink Olga , Nash Andrew , Weidmann Ulrich
Published: December 2013

European passenger rail systems are massively interconnected and operate with very high frequency. The effects of single-component failures on these types of systems can significantly affect technical and operational reliability. Today advanced diagnostic tools with broad functionalities are being added to systems and system components. These tools control the operation of, support the maintenance of, and monitor the highly sophisticated and interconnected components. A set of diagnostic event data from a passenger train exterior door system was used to predict the occurrence of events that might evolve into operational disruptions that affect train operation and therefore railway reliability. This approach used a neural network algorithm with dynamic temporal behavior (the echo state network) in combination with principal component analysis. The proposed approach exhibited a prediction accuracy of up to 99%.
Hierarchical Decomposition Methods for Periodic Railway Timetabling Problems
Authors: Herrigel Sabrina , Laumanns Marco , Nash Andrew , Weidmann Ulrich
Published: December 2013

Today many European railway networks are operating near capacity. Developing timetables for these dense and often highly congested networks is becoming increasingly difficult. Several algorithmic approaches for solving timetabling problems have been developed in recent years, but the problem size, computational complexity, and lack of transparent interfaces for planners slow down adoption of these approaches in practice. This research proposed an iterative method based on train hierarchies to solve large periodic timetabling problems. The proposed method added a new group of trains to the schedule in each step of the process while holding trains added in previous steps fixed within a specified time interval. A case study with real-world data was used to analyze the influence of the number of decomposition steps and time interval on computation time and timetable quality. The results showed that setting parameters to a compromise between the extremes of a purely sequential or a purely simultaneous timetable planning approach was very effective at reducing computation time while still providing optimal or close-to-optimal timetables.
Impact of European Railway Traffic Management System on Human Performance in Railway Operations
Authors: Smith Peri , Kyriakidis Miltos , Majumdar Arnab , Ochieng Washington Y.
Published: December 2013

The safety of railway system operations depends on several internal and external factors. The former include rail traffic rules, infrastructure, rolling stock reliability, organizational safety culture, and human factors. The railway systems in Europe, North America, and Australasia have seen significant technological developments for improved capacity and efficiency. Europe, for instance, is implementing the European Railway Traffic Management System (ERTMS). However, transition to a more automated traffic management system requires, among other things, changes to infrastructure, rolling stock, operational procedures, or all three. Concerning operational procedures, the literature shows that train drivers, signalers, and controllers have the greatest effect on the safety of a railway network. Therefore, the reliability and safety integrity of the railway network are largely dependent on human factors, in particular, the performance of human operators. This performance in turn is affected by a number of factors broadly known as performance-shaping factors (PSFs), with deficiencies in communication accounting for more than 90% of incidents for the conventional railway system. Therefore, this study investigated the influence of ERTMS and in particular the Global System for Mobile Communications–Railway (GSM-R) on operators' performance. The study analyzed 74 accident and incident reports of railway operations before and after GSM-R implementation from several European railway organizations. The results identified the communications-related factors that affected human performance in the conventional and upgraded railway system based on the existing railway–PSF taxonomy. Finally, the results showed the positive impact of GSM-R implementation on operators' performance.
Modeling Rail Operating Costs for Multimodal Corridor Planning
Authors: Owens Travis D. , Seedah Dan P. K. , Harrison Robert
Published: December 2013

Cost and delivery times are key variables used by shippers to determine freight mode choice. Unfortunately, transportation planners wishing to examine truck versus rail trade-offs on major state and regional corridors use models that rarely capture the effects of cargo weight, running speeds, network capacity, or route characteristics, even though they are key inputs to any logistical analysis. Moreover, current models are incapable of fully internalizing external or social costs into their calculations, a failure that becomes more important as sustainable strategies are sought by society. Therefore, in three critical areas of transportation planning—network capacity, route features, and operating characteristics—most existing models are deficient. This study gives planners a mechanistic method to determine variable rail costs on a single corridor. When this model is combined with the latest truck operating cost mechanistic models, the cost differentials that underlie the choice of truck versus rail will be revealed. The model, C-TRIT, is part of a study sponsored by the Texas Department of Transportation to support freight movement on the extensive state network of multimodal corridors.
Safety Effectiveness of Integrated Risk Reduction Strategies for Rail Transport of Hazardous Materials
Authors: Liu Xiang , Saat M. Rapik , Barkan Christopher P. L.
Published: December 2013

Railroad transportation plays a critical role in safely and economically moving hazardous materials throughout North America. Effective management of the risk of hazardous materials transportation is a high priority of both the American rail industry and government. A number of strategies and technologies have been implemented or are being developed to reduce this risk. Each risk reduction strategy has an effect on rail safety as well as a corresponding implementation cost. In addition, risk reduction strategies may have interactive effects. However, little prior research has addressed the interactive effects between different risk reduction strategies or how elements of them should be compared or combined, or both, to achieve the maximum risk reduction in the most cost-effective manner. A preliminary methodology was developed to estimate the reduction in the risk of the release of hazardous materials by implementing integrated risk reduction strategies, including accident prevention, tank car safety design enhancement, and changes in train operating practices such as train speed reduction. An analysis showed that risk reduction was affected in differing degrees by operating conditions, accident cause, effectiveness of accident prevention technologies, tank car safety design, percentage of tank car fleet requiring upgrade, and train speed. This study represents the first step in a systematic process of quantitative risk analysis of railroad freight transportation for local, regional, and systemwide safety improvement and is intended to assist decision makers in the development of an integrated cost-efficient risk reduction framework.
Comparison of Capacity of Single- and Double-Track Rail Lines
Authors: Sogin Samuel L. , Lai Yung-Cheng (Rex) , Dick C. Tyler , Barkan Christopher P. L.
Published: December 2013

Federal, state, and regional transportation authorities have shown an increased interest in adding or increasing passenger rail service between many city pairs. The most commonly proposed approach has been to operate passenger trains on existing freight railroad infrastructure. However, operation of passenger and freight trains on the same infrastructure poses a variety of challenges because of their different performance characteristics. In addition, track configuration—single versus double track—can significantly influence the interaction effects between trains. The maximum speed of passenger trains has little impact on the performance of freight trains on single-track lines. However, in double-track configurations, the speed of the passenger train has a major impact on freight train delays. Single-track operation can show an asymmetrical delay distribution centered on an average run time, with very few trains arriving close to the minimum run time. A double-track configuration can result in a delay distribution shaped similarly to an exponential distribution with many trains maintaining their minimum run times. In both single- and double-track operations, a higher passenger train maximum speed can lead to a greater range of possible travel times. These analyses can help transportation authorities further understand the interactions between passenger and freight trains for current and future shared-corridor operations.
Use of Recycled Tire Rubber to Modify Track–Substructure Interaction
Authors: Ho Carlton L. , Humphrey Dennis , Hyslip James P. , Moorhead William
Published: December 2013

Resiliently bound ballast (RBB) is a new engineered material being developed as an alternative or supplement to conventional ballast for use in transit, passenger, and freight railways to improve mechanical behavior and control the modulus and damping when recycled tire waste material is used. RBB is a stable mixture of standard ballast stone and tire-derived aggregate (TDA) bound together with a purpose-designed resilient epoxy binder. Initial laboratory tests were conducted on specimens 6 in. (151 mm) and 10 in. (254 mm) in diameter of two mixes of RBB. Tests were conducted on fully bound (cemented) samples of ballast, TDA, and epoxy as well as individual particles with TDA bound to the individual ballast particles with the resilient epoxy binder. The tests included static triaxial compression tests and dynamic cyclic triaxial tests. Static tests indicated that the addition of the TDA and epoxy resulted in an increase in cohesive strength. The dynamic tests indicated changes in modulus and damping depending on the mixture of rock, TDA, and epoxy. One proposed use of RBB is to affix the RBB to the bottom of concrete ties to modify the interaction between the tie and the ballast material and improve ballast durability and modify resilience and damping. Box tests were conducted on a section of concrete tie with and without RBB attached. The tie with a section of rail attached was vertically loaded with a sinusoidal load to model repetitive axle loading. Observations indicated that the box test that used a concrete tie without RBB produced more ballast breakage compared with the test that used a concrete tie with RBB; however, more abrasion between particles occurred with the RBB-bound tie.
Simulating Ballast Shear Strength from Large-Scale Triaxial Tests
Authors: Qian Yu , Lee Seung Jae , Tutumluer Erol , Hashash Youssef M. A. , Mishra Debakanta , Ghaboussi Jamshid
Published: December 2013

The railroad ballast layer consists of discrete aggregate particles, and the discrete element method (DEM) is the most widely adopted numerical method to simulate the particulate nature of ballast materials and their particle interactions. Large-scale triaxial tests performed in the laboratory under controlled monotonic and repeated loading conditions are commonly considered the best means to measure macroscopic mechanical properties of ballast materials, such as strength, modulus, and deformation characteristics, directly related to load-carrying and drainage functions of the ballast layer in the field. A DEM modeling approach is described for railroad ballast with realistic particle shapes developed from image analysis to simulate large-scale triaxial compression tests on a limestone ballast material. The ballast DEM model captures the strength behavior from both the traditional slow and the rapid shear loading rate types of monotonic triaxial compression tests. The results of the experimental study indicated that the shearing rate had insignificant influence on the results of the triaxial compression tests. The results also showed that the incremental displacement approach captured the measured shearing response, yet could save significant computational resources and time. This study shows that the DEM simulation approach combined with image analysis has the potential to be a quantitative tool to predict ballast performance.
Track Stiffness Transition Zone Studied with Three-Dimensional Sandwich Track Model
Authors: Huang Hai , Brennecke Braun
Published: December 2013

When railroad tracks pass from an earthen subgrade to a bridge, the tracks become uneven. In fact, even if the tracks are level at the time of construction, over time a dip develops. This phenomenon occurs just in front of the bridge and is a cause of greater maintenance and poor ride quality. The track before bridges typically needs to be resurfaced more frequently; this maintenance increases the cost for a railroad owner. The cause for this dip in the track is believed to be the sudden change in stiffness between the subgrade and the bridge. The most commonly used approach to neutralize this sudden stiffness change is called the stiffness transition zone method. The idea is to spread out the stiffness jump from a few centimeters to the length of about 30 m by gradually changing the stiffness of the track. However, the details of the stiffness transition zone—for instance, the length, the pattern of the stiffness change, and the effect of train speed—have yet to be studied. A dynamic track model called the three-dimensional sandwich model was developed to study and compare different stiffness transition scenarios properly. In general, results showed that the transition zone decreased the tie–ballast contact force. An increase in speed will increase the tie–ballast contact force both with and without the transition zone. A longer exponentially increasing stiffness transition zone was proved to be better in terms of decreasing the tie–ballast contact force than was the linearly increased transition zone.
Simulation-Based Rail Transit Optimization Model
Authors: Kim Myungseob (Edward) , Schonfeld Paul , Kim Eungcheol
Published: December 2013

A proposed bilevel optimization process determines the depth of a dipped vertical alignment between rail transit stations as well as the cruising speed for each direction. This model also considers how regenerative braking may affect vertical alignment decisions. The optimized depth and directional cruising speeds were jointly obtained in a numerical example. A sensitivity analysis showed that regenerative braking reduced the total cost but did not significantly change the optimized depth of the dipped vertical alignment. The developed model is more realistic and useful than previous ones because it allows unequal station elevations, jointly optimizes decision variables, and considers regenerative braking.
Characterization of Railroad Ballast Behavior under Repeated Loading
Authors: Mishra Debakanta , Kazmee Hasan , Tutumluer Erol , Pforr James , Read David , Gehringer Eric
Published: December 2013

Characterizing railroad ballast behavior under repeated train loading is of significant importance for evaluating field settlement or permanent deformation potentials of unbound aggregate ballast layers. For the proper characterization of ballast behavior under dynamic loading, a new triaxial test setup was recently developed at the University of Illinois at Urbana–Champaign. Capable of accommodating cylindrical specimens with a diameter of 305 mm (12 in.) and a height of 610 mm (24 in.), this closed-loop servohydraulic test setup used a load cell and four displacement transducers mounted on the specimen to quantify deformation behavior under loading. Preliminary test results evaluating effects of different applied stress states as well as geogrid reinforcement on ballast behavior established the consistency and repeatability of this new test equipment. Laboratory findings are presented from an ongoing research study aimed at investigating the effects of different ballast types and field degradation trends on permanent deformation accumulation. The ballast type with the highest mill abrasion value was found to accumulate the highest permanent deformation under repeated load triaxial testing. Permanent deformation trends observed for four other ballast types showed direct correlations to the degrees of particle degradation observed in track sections constructed with these ballast materials and trafficked for approximately 18 months with a total track usage of 320 million gross tons.
Investigation of Aggregate Properties Influencing Railroad Ballast Performance
Authors: Wnek Michael A. , Tutumluer Erol , Moaveni Maziar , Gehringer Eric
Published: December 2013

Class I freight railroads nearly exclusively use premium, high-quality ballast aggregates such as granite, trap rock, and quartzite for their mainline ballast needs. These natural virgin aggregates are crushed stones with certain geologic origins, and their properties may vary significantly depending on quarry sources and production techniques. Findings are presented from a comprehensive laboratory study on ballast aggregates undertaken at the University of Illinois to investigate differences in engineering behavior of premium railroad ballast materials obtained from 13 quarries across the Union Pacific Railroad system. Laboratory research tasks consisted of gradation analysis; quantifications of shape, texture, and angularity properties with the University of Illinois aggregate image analyzer; shear strength evaluation by using large direct shear (shear box) tests; and ballast degradation and durability analyses with Los Angeles abrasion tests conducted at 400 and 1,000 turns and evaluations of subsequent ballast fouling. As the compacted ballast voids ratio increased, aggregate strength typically decreased because of lower solid densities obtained from shear box testing. Aggregate shape properties quantified through imaging-based shape indices were shown to be linked to the strength properties of different ballast density groups. One of the ballast aggregates with flat and elongated particles but very strong mineralogy had quite high strength properties despite the tendency for particles to break during shearing. Higher angularities that generally resulted in higher strength properties could also yield higher fouling and increased breakdown potential of the aggregates.
Measuring Rail Seat Pressure Distribution in Concrete Crossties
Authors: Rapp Christopher T. , Dersch Marcus S. , Edwards J. Riley , Barkan Christopher P. L. , Wilson Brent , Mediavilla Jose
Published: December 2013

A sustained increase in gross rail loads and cumulative freight tonnages as well as growing interest in high-speed passenger rail development is placing an increasing demand on North American railway infrastructure. To meet this demand, improvements to the performance and durability of concrete crossties and fastening systems are necessary. One of the typical failure modes for concrete crossties in North America is rail seat deterioration, and researchers have hypothesized that localized crushing of the concrete in the rail seat is one of the potential mechanisms that contributes to this failure mode. To understand this mechanism better, the University of Illinois at Urbana–Champaign is using a matrix-based tactile surface sensor to measure and quantify the forces and pressure distribution acting at the contact interface between the concrete rail seat and the bottom of the rail pad. Preliminary data collected during laboratory experimentation have shown that a direct relationship existed between rail pad modulus and maximum rail seat pressure. In addition, under a constant vertical load, a direct relationship between the lateral-to-vertical force ratio and the maximum field side rail seat pressure was observed. Given that all preliminary results indicate that various combinations of pad modulus, track geometry, and lateral-to-vertical force ratio create localized areas of high pressure, crushing remains a potential mechanism leading to rail seat deterioration. Through the analysis of rail seat pressure data, valuable insight can be gained that can be applied to the development of designs for concrete crosstie and fastening system components that meet current and projected service demands.
Characterization of Opposite-Direction Road Departure Crashes in the United States
Authors: Kusano Kristofer D. , Gabler Hampton C.
Published: December 2013

Opposite-direction crashes can be extremely severe because opposing vehicles often have high relative speeds. The objective of this study was to characterize the overall frequency of opposite-direction crashes as well as the frequency of crashes involving fatalities and serious injuries. The results of the study will guide future research and investment in infrastructure-based countermeasures to opposite-direction crashes, such as centerline rumble strips. The study used data from the National Automotive Sampling System (NASS) General Estimates System for 2010, the NASS Crashworthiness Data System for 2006 to 2010, and the Fatality Analysis Reporting System for 2010. The most common opposite-direction crash scenario was a driver departing the road driving over the centerline or the road edge to the left, which accounted for only 5% of nonjunction vehicle-to-vehicle crashes but 44% of serious injury and 49% of fatal crashes of the same type. Of the cross-over-to-left crashes, 72% of fatal crashes occurred on rural, undivided, two-lane roads and accounted for 1,659 fatal crashes in 2010. In cross-over-to-left crashes on rural two-lane roads, the driver was going straight or negotiating a curve in 88% to 94% of the crashes. The driver was overtaking another vehicle in only 2% of serious injury crashes and 6% of fatal crashes. Cross-over-to-left crashes on curves were to the outside of the curve more often than to the inside of the curve. This research suggests that countermeasures to opposite-direction crashes should focus on rural two-lane roads.
Injury Risk Posed by Side Impact of Nontracking Vehicles into Guardrails
Authors: Johnson Nicholas S. , Gabler Hampton C.
Published: December 2013

Side impact is one of the most dangerous types of guardrail crashes. Of particular concern is a nontracking vehicle sliding sideways into a guardrail end treatment. This study investigated the issue of end terminal-side crashes with the use of a data set of 142 guardrail crashes extracted from the National Automotive Sampling System–Crashworthiness Data System. Side crashes involving an end terminal were substantially over-represented in driver injuries. End terminal contact occurred in about 25% of all guardrail-side crashes but represented almost 70% of driver injuries. Terminals that were noncompliant with NCHRP Report 350 were roughly five times as likely as compliant designs to cause serious crash injury. Collisions with terminals were also about twice as likely to initiate rollover compared with collisions with the length-of-need section of the guardrail. When injuries caused by rollovers, unbelted drivers, and driver ejections were accounted for, the risk presented by terminal contact was accentuated, as was the difference between cars, light trucks, and vans in terminal impacts.
Retrofit Bridge Rail Design and Testing for a Historic Texas Steel Truss Bridge
Authors: Williams William
Published: December 2013

The State Loop 481 steel truss bridge over the Llano River in Junction, Texas, is classified as a historic structure. The bridge is approximately 1,423 ft long and has a railing that attaches directly to the steel truss members and does not meet the current AASHTO Test Level 2 (TL-2) strength requirements. Many supporting truss members were not adequate to resist TL-2 crash force. The purpose of this research was to design a crashworthy retrofit bridge rail that met the current AASHTO TL-2 strength requirements without overstressing the supporting truss members. The new design maintains the historic appearance of the structure. This paper presents details of the new bridge rail design and an analytical procedure for determining the magnitude of force transmitted to the supporting truss members. Crushable-pipe blockouts located between the new retrofit rail design and the truss members were developed as part of this research and were used to minimize the crash force transmitted to the steel truss members. The new bridge rail design was successfully crash tested in accordance with the TL-2 requirements of NCHRP Report 350. A bridge rail expansion splice was developed for the new bridge rail design and was successfully crash tested in accordance with the Test Level 3 requirements of NCHRP Report 350. This paper presents the results of this research, details of the expansion splice, the new bridge rail design, the design procedure, and the results of the crash testing.
Some Limitations of the Models in the Highway Safety Manual to Predict Run-off-Road Crashes
Authors: Miaou Shaw-Pin
Published: December 2013

Crash-prediction models in the current edition of the Highway Safety Manual (HSM) have been developed to predict crash frequency by collision type and severity level for specific types of roadways and sites. Each model is made up of three major components: safety performance functions (SPFs), crash modification factors, and calibration factors. The objective of this study was to identify the limitations of the prediction models in estimating single-vehicle, run-off-road (SVROR) crashes for roadside safety analyses and suggest needed changes and developments. The paper presents a review of the state of the models in HSM and focuses on SPFs. Data from FHWA's safety effects of cross-section design for two-lane roads database were used to gain insight about the characteristics of SVROR crashes and total crashes, and to identify the limitations of the current models in predicting the frequency, type, and severity of SVROR crashes. Three major areas of limitations of SPFs are discussed: (a) assumptions involved in development, (b) variables that are potentially important to roadside design but not considered, and (c) statistical bias and uncertainty of the model equations.
Crash Wall Design to Protect Mechanically Stabilized Earth Retaining Walls
Authors: Abu-Odeh Akram Y. , Kim Kang-Mi
Published: December 2013

Mechanically stabilized earth (MSE) retaining walls are used to provide roadway elevation for bridge approaches, underpass frontage roads, and other roadway elevation applications. Vehicular traffic may exist on the high (fill) side of the MSE retaining wall, the low side, or both sides. For traffic on the high side, a conventional traffic barrier might be placed on or near the top of the wall and mounted on a moment slab or a bridge deck. For traffic on the low side, a conventional traffic barrier might be installed adjacent to the wall or the wall itself may serve as the traffic barrier. Typical MSE wall panels are not designed to resist vehicle impacts. Therefore, structural damage to the wall panels and the earth fill would require complicated and expensive repairs. A simple reinforced-concrete crash wall constructed in front of the MSE wall panels could significantly reduce damage to the panels. It might prove practical to implement such a design to reduce costly repairs to the MSE wall structure. In this paper, LS-DYNA finite element analysis code was used to model and analyze a sacrificial crash wall design to determine its effectiveness in protecting an MSE retaining wall. Based on the LS-DYNA simulations, a crash wall that is 8 in. (0.2 m) thick is considered to be an adequate design to reduce damage to the MSE wall.
Dynamic Evaluation and Implementation Guidelines for a Nonproprietary W-Beam Guardrail Trailing-End Terminal
Authors: Mongiardini Mario , Faller Ronald K. , Reid John D. , Sicking Dean L.
Published: December 2013

Most state departments of transportation use simple adaptations of crashworthy guardrail end terminals, which typically include breakaway posts and an anchor cable, for downstream anchorage systems. The guardrail safety performance for vehicular impacts occurring in close proximity to these simplified, downstream anchorage systems is not well known. Further, the length of need (LON) for the downstream end of these systems has yet to be adequately determined. This research project assessed the safety performance of the Midwest Guardrail System (MGS) for impacts occurring in close proximity to a nonproprietary, trailing-end guardrail terminal under the Test Level 3 conditions of the Manual for Assessing Safety Hardware. The two research objectives were to (a) determine the end of the LON for impacts with light pickup trucks and (b) investigate potential risks for a small passenger car to become unstable when striking the downstream end of the MGS anchored by the nonproprietary, trailing-end terminal. Numerical simulations were carried out to identify the most critical impact location for the 1100C small car and the end of the LON for the 2270P pickup truck. In full-scale crash tests, considerable snag of the 1100C vehicle occurred; however, occupant risk values and vehicle stability were within acceptable limits. The crash test with the 2270P pickup indicated that the end of the LON was located at the sixth post from the downstream-end post. Guidelines were proposed for installing the MGS to shield hazards in close proximity to the tested nonproprietary, trailing-end terminal.
Motorcyclist Impacts into Roadside Barriers
Authors: Grzebieta Raphael , Bambach Mike , McIntosh Andrew
Published: December 2013

This paper reports on a study that reviewed the European Standard EN 1317-8 for motorists crashing into barriers and the relevance to Australian motorcycle fatalities. The data collection and analysis of 78 Australian motorcyclist-into-barrier fatalities described here were used to justify the review. In Australia each year approximately 15 motorcyclists die from striking a road safety barrier. A retrospective analysis of the fatalities during 2001 to 2006 (n = 78) was carried out. Consistent with European findings, approximately half the motorcyclists were in the upright posture when they struck the barrier, whereas half slid into the barrier. The mean precrash speed was 100.8 km/h, and the mean impact angle was 15.48. The areas of the body that were injured were similar across different barrier types (concrete, wire rope, and W-beam) and crash postures. The thorax area had the highest incidence of injury and maximum injury in fatal motorcycle crashes into barriers; the head area had the second-highest incidence of injury. Moreover, thorax and pelvis injuries had a greater association with sliding crashes than with those in the upright posture. The existing European Standard EN 1317-8 addresses only the sliding mechanism, uses a head injury criterion, and does not specify any thorax injury criterion. It was proposed that a thorax injury criterion and an additional test should be introduced with the rider in the upright position when striking the barrier and then sliding along the top of the barrier.
Safety Effectiveness of “Vehicle Entering When Flashing” Signs
Authors: Simpson Carrie L. , Troy Shawn A.
Published: December 2013

This project evaluated the safety effectiveness of “Vehicle Entering When Flashing” (VEWF) intersection conflict warning systems (ICWSs) at stop-controlled intersections. The North Carolina Department of Transportation has utilized this treatment, which consists of vehicle-actuated sign and flasher assemblies placed at or near the intersection to warn motorists on the major or minor road, or both, of vehicles entering the intersection. Although this countermeasure has been used for years in North Carolina, and similar ICWSs have been used in other states, there has been minimal safety evaluation to prove or validate the systems' effectiveness. This study evaluated four categories of VEWF systems. Sites were categorized on the basis of the direction of the alert and placement from the intersection. Crash modification factors (CMFs) were provided for all sites and each category, as well as exclusively for sites with two-lane at two-lane intersections. Empirical Bayes before-and-after techniques were used to overcome the regression to the mean threat. Deployments with major road alerts in advance of the intersection and a combination of both major and minor road alerts were determined to be most effective for two-lane at two-lane stop-controlled intersections with CMFs for total crashes of 0.68 and 0.75, respectively.
Countdown-Only Pedestrian Change Interval Displays
Authors: Scott Alan C. , Swenson Lindsay J. , Bentzen Billie Louise , Barlow Janet M.
Published: December 2013

This study evaluated the effect of visual pedestrian signal displays on the ability of persons with reduced visual acuity to accurately and confidently identify the pedestrian interval. While watching video clips of actual intersections presented on a 42-in. monitor under simulated visual impairment, participants attempted to determine the pedestrian interval (“Walk,” flashing “Don't Walk,” or steady “Don't Walk”) and provided confidence ratings for each judgment. Participants in Experiment 1 experienced simulated acuities of 20/70, 20/100, and 20/200; participants in Experiment 2 experienced approximate acuities of 20/20, 20/50, and 20/300. The study made a critical comparison of two methods of signaling the pedestrian change interval (i.e., flashing “Don't Walk”): (a) simultaneous presentation of a countdown and a flashing upraised hand symbol and (b) a countdown-only display without the flashing upraised hand. With the exception of performance in the 20/300 vision category, participants' accuracy on the interval discrimination task was, overall, rather high. However, under simulated visual impairment of 20/70 or worse, participants' success in correctly determining the pedestrian interval was, on average, 21.5 percentage points lower for the countdown display presented without the flashing upraised hand than for the countdown display with the upraised hand. The participants' average reported confidence in their judgment was also lower for the countdown-only condition, and their interval judgment response times also showed a negative effect of the countdown-only display. Implications of the study findings with regard to visual impairment and signal displays for the pedestrian change interval are discussed.
Evaluation of Driver Perception–Reaction Time under Rainy or Wet Roadway Conditions at Onset of Yellow Indication
Authors: El-Shawarby Ihab , Abdel-Salam Abdel-Salam G. , Rakha Hesham
Published: December 2013

The research presented in this paper characterizes the impact of a wet pavement surface and rainy weather conditions on driver perception–reaction time (PRT) at the onset of the yellow indication on the approach to a high-speed signalized intersection. An in-vehicle differential Global Positioning System was used in a controlled field environment. Three hundred eighty-four data records for all drivers who stopped at the onset of the yellow indication were available for analysis. The minimum time to intersection (TTI) ranged from 2.35 s to 5.71 s. Statistical analyses were used to quantify the effects of the TTI, grade (uphill or downhill), gender, and age (<40 years, 40 to 59 years, and ≥60 years) on driver PRT. The study demonstrated that driver PRT increases as TTI increases. A longer PRT was found when vehicles traveled along an upgrade section, given that the driver was typically accelerating when the yellow indication was initiated. No gender differences were found in PRT, and no statistically significant differences were found between different age groups. Furthermore, the study demonstrated that driver PRT increased under conditions of a wet pavement surface and rainy weather as compared with clear weather conditions over the entire TTI range.
Fuzzy Logic for Improved Dilemma Zone Identification
Authors: Moore Derek , Hurwitz David S.
Published: December 2013

A Type II dilemma zone (DZ) is the segment of roadway on the approach to an intersection at which drivers have difficulty deciding whether to stop or proceed at the onset of the circular yellow (CY) indication. The safety of signalized intersections is improved when DZs are correctly identified and steps are taken to reduce the likelihood that vehicles will be caught in such zones. This research purports that using driving simulators as a means of collecting driver response data at the onset of the CY indication is a valid methodology for augmenting analysis of decisions and reactions made within the DZ. The data obtained were compared with data from previous experiments documented in the literature, and the evidence suggested that driving simulation was valid for describing driver behavior under the given conditions. After the data were validated, fuzzy logic was proposed as a tool for modeling driver behavior in the DZ, and three models were developed to describe driver behavior as it relates to the speed and position of the vehicle. These models were shown to be consistent with previous research on this subject and were able to predict driver behavior with up to 90% accuracy.
Behavior of Left-Turning Drivers during Permissive Interval of Protected–Permissive Operation
Authors: Rietgraf Ashley , Schattler Kerrie L.
Published: December 2013

A study was conducted to assess the differences in operations and driver behavior in response to three signal displays for the permissive interval of a protected–permissive left-turn (PPLT) phase. A comparative two-phased approach based on field observations and video recordings of driver behavior was used to conduct the research. Phase 1 examined driver behavior at six intersection approaches in Peoria, Illinois, that operated with different permissive left-turn displays: circular green (CG), flashing yellow arrow (FYA), and flashing red arrow (FRA). The CG indication had been the predominant indication used for the left-turn permissive indication in Peoria until 2010, when FYAs were installed throughout the city. FRAs are operated at two adjacent intersections in Peoria and were installed as a site-specific countermeasure. The Phase 1 findings showed that the highest proportion of drivers' safe and efficient actions was in response to the FYA as compared with the CG and FRA displays. In Phase 2, a comparative analysis of four intersection approaches was conducted to determine the impact on driver understanding of the permissive left-turn CG display in two geographic areas: one in Peoria, where multiple permissive left-turn signal indications for the PPLT phase (CG, FYA, and FRA) are currently in use, and one in Blooming-ton, Illinois, where only the CG indication is used. The Phase 2 research found, on the basis of observed safe and efficient driver actions, that there were no differences in driver understanding of the CG permissive left-turn display at the study approaches in the two cities.
Possible Expectancy Violations on Frontage and Conventional Roads at Interchanges
Authors: Nelson Alicia , Tydlacka Jonathan , Chrysler Susan T. , Voigt Anthony
Published: December 2013

The intersection and mandatory movement lane control signs placed on intersection approaches are critical to safe and efficient intersection operations. Ramp, frontage road, and cross-street approaches to interchanges often widen at intersections to accommodate additional through or turn lanes. Currently, there is inconsistency in conveying to drivers how they should align themselves upstream of a diamond intersection to maneuver for their desired turning movement as the intersection widens. These inconsistencies can result in drivers making an incorrect lane selection that may result in late lane changes or illegal turns. This paper focuses on the expectancy violations that were discovered by a driver survey portion of a larger project that included practitioner surveys and a field evaluation of sign alternatives. A computer-based driver survey sampled 204 Texas drivers in four cities. The questions reported in this paper focused on driver expectations of lane movement and assignment on frontage road approaches to cross streets on freeway on- and off-ramps. Findings that showed that drivers are often incorrect in their assumptions about lane assignment when approaching intersections indicate a greater need for advanced lane control signs. A new sign design, adopted from Australian practice, that graphically shows lane additions and drops was the most effective for cases in which the downstream geometry varied from the driver's expectations.
Evaluation of Impact of Modern Headlamp Technology on Design Criteria for Sag Vertical Curves
Authors: Gibbons Ronald B. , Flintsch Alejandra Medina , Williams Brian , Du Jianhe , Rakha Hesham
Published: December 2013

This paper includes a review of the current methodologies used in the design of sag vertical curves, a review of the changes in headlamp technologies, the results of a survey of practitioners and two visibility experiments, and conclusions. The review of the headlamp technology shows that, over time, headlamp technologies have increasingly limited the amount of light emitted above the horizontal axis of the headlamp. In addition to the regulatory impact, headlamp technologies such as visually optically aligned systems also limit the upward divergence of the light beam from the longitudinal axis of the vehicle (uplight). The practitioner survey found that very few deviations from AASHTO design methodologies were used. On the basis of the practitioner review, the potential to modify current methodologies is limited to the manipulation of the vehicle speed, deceleration, and change in angle of curvature. The results of the visibility experiments showed that participants detected objects at distances that were significantly shorter than the stopping sight distance (SSD), not only in sag vertical curves but also on flat roadway. This finding indicated that even if sag vertical curves were redesigned, visibility distance would still be shorter than SSD because the headlamps would be the limiting factor. A review of the potential modifications to the design of sag vertical curves (which were suggested in the responses to the practitioner survey) found that these changes would be inadequate to make up the difference between visibility distance and SSD.
Assessment of Background Complexity of Overhead Guide Signs
Authors: Ge Hancheng , Zhang Yunlong , Miles Jeffrey D. , Carlson Paul J.
Published: December 2013

Researchers have developed a systematic method of using image-processing techniques to assess the complexity of the background of overhead guide and street name signs under nighttime driving conditions. These techniques are used to extract image properties such as entropy, contrast, energy, homogeneity, the number of saturation pixels, the edge ratio, and the number of objects, all of which are considered potential factors for evaluating background complexity. The researchers combined these factors with ratings of images by human survey participants to develop a multiple linear regression model that could be used by practitioners to evaluate the background complexity of overhead guide and street name signs under nighttime conditions. Because of the small number of samples in the data sets, bootstrapping, a resampling method, was employed to improve the performance of the proposed model. High consistency between the results of the proposed model and the empirical results from the survey demonstrated that the model performed well in analyzing the complexity of the background of traffic signs. Practitioners can use this model to identify overhead guide and street name signs that have highly complex backgrounds and may require sign lighting, supplemental signs, or relocation to minimize driver difficulty in detecting and obtaining information from the signs.
Analysis of Nighttime Visibility of In-Service Pavement Markings
Authors: Ye Fan , Carlson Paul J. , Miles Jeffrey D.
Published: December 2013

Traditionally, retroreflectivity is used to quantify the visibility of traffic control devices, including pavement markings. However, retroreflectivity is a physical property of a material that is used as a surrogate for luminance. By itself, retroreflectivity is limited to describing the visibility of pavement markings at night. One way to quantify the visibility of pavement markings at night is to assess the visibility level (VL) from the perspective of a driver's visual demands. This paper introduces an extended VL model for pavement markings that is based on previous research on VL modeling. This model was used to determine the visibility of in-service pavement markings along lit and unlit sections of highway in Anchorage, Alaska. The measured retroreflectivity of the pavement markings was compared with the FHWA proposed minimum retroreflectivity levels for pavement markings, and the calculated VL was compared with the implied visibility of the pavement markings (also calculated from the VL model) as derived from the FHWA proposed minimum retroreflectivity levels. The results indicated that the visibility of areas with continuous roadway lighting appeared to be more than adequate, despite low retro-reflectivity levels. The benefit of the roadway lighting was most evident when the retroreflectivity of the pavement markings was relatively low and at the longer distances tested (54 and 64 m).
Nature = Life: Environmental Identity as Resistance in South Sinai
Authors: Gilbert Hilary
Published: December 2013

Sedentarization and 'development', under Israeli Occupation (1967- 1982) and subsequent Egyptian rule, have eroded the agropastoral livelihoods of South Sinai Bedu and the strong cultural identity that evolved from them. Unequal access to work and poor education have produced material poverty, while government policy to 'Egyptianize' Sinai has marginalized Bedouin culture. This article explores the impacts on Bedu of living with multiple inequalities, and the strategies people employ to validate themselves in a system that disdains or ignores them. Among the most important is adopting a self-appointed role as guardians of nature. Bedu are choosing to reformulate an environmental identity as an act of symbolic resistance to Egyptianization, and to a neglect of the environment that they feel, with good reason, extends to them.