Terms Of Traffic Safety Research Articles

Modeling safety performance of the new super DDI design in terms of vehicular traffic and pedestrian

Most existing interchanges in the United States were built more than 50 years ago based on old design policies. Many of these designs are not consistent with current traffic and pedestrian demands anymore. Therefore, this inconsistency has caused problems regarding operation and safety. This paper models safety performance of a new design called super diverging diamond interchange (super DDI) considering VISSIM simulation and surrogate safety assessment model (SSAM). Six other interchange designs were also considered for comparing to the new super DDI design. Overall, 252 simulation scenarios were modeled in VISSIM and then tested by SSAM. Also, the same number of tests were considered to evaluate pedestrian performance of the designs considered in this study. Based on results, super DDI showed a high potential either in terms of traffic safety and pedestrian safety. In comparison to other designs, super DDI had the minimum number of simulated conflicts as well as the lowest mean speed and time to collision (TTC) of simulated conflicts. This fact shows that super DDI could perform promising in reducing crash frequency and crash severity. Reviewing the geometry of the super DDI, lower traffic involving in each conflict point should be one of the main reasons for the promising traffic safety performance of the design. Regarding pedestrian performance, super DDI got the third rank of the lowest mean pedestrian travel times. There is no free-flowing conflict between vehicles and pedestrians in a super DDI. Therefore, pedestrian paths of the super DDI are predicted to be safer than the paths in a typical DDI design.

Classification of Drugs Listed in Iranian Pharmacopoeia Based on Impact on Driving Performance

According to studies, drugs based on their Pharmaco-dynamics and pharmacokinetics can affect driving performance. There are clear conclusions about some medications and in other drugs have not yet reached definitive conclusions. There are two international experiences regarding the classification of drugs based on their impact on driving performance. These projects are DRUID (Driving Under the Influence of Drugs and medicines) and ICADTS projects. This study conducted to classify Iranian pharmacopeia according to drugs effects on driving performance. The projects divided the drugs used in the treatment of diseases into three categories in terms of traffic safety. The project first identified and explored similar experiences in the world by reviewing scientific resources. For the medicines that their effects were determined in the existing classifications, their impact category were extracted from DRUID and ICADTS systems. For drugs that have different categories in two systems or unidentified their effects on these classifications, Drug side effects, especially in areas of attention, cognition, sleep, vital signs were extracted from pharmacology and other related textbooks. With using appropriate keywords, the studies and evidences about these drugs effects on driving were assessed. At an expert meeting, with review of side effects and scientific evidences, the impact of these drugs on driving performance was determined. Finally, the effect of drugs on driving performance was classified into three groups with no or minimal, moderate and severe effects. Based on these classification results, a mobile application was designed and prepared for ordinary people. In this application, for any drug their effect category, side effects and prevention strategies were explained.

A Path Loss and Shadowing Model for Multilink Vehicle-to-Vehicle Channels in Urban Intersections.

The non line-of-sight (NLOS) scenario in urban intersections is critical in terms of traffic safety—a scenario where Vehicle-to-Vehicle (V2V) communication really can make a difference by enabling communication and detection of vehicles around building corners. A few NLOS V2V channel models exist in the literature but they all have some form of limitation, and therefore further research is need. In this paper, we present an alternative NLOS path loss model based on analysis from measured V2V communication channels at 5.9 GHz between six vehicles in two urban intersections. We analyze the auto-correlation of the large scale fading process and the influence of the path loss model on this. In cases where a proper model for the path loss and the antenna pattern is included, the de-correlation distance for the auto-correlation is as low as 2–4 m, and the cross-correlation for the large scale fading between different links can be neglected. Otherwise, the de-correlation distance has to be much longer and the cross-correlation between the different communication links needs to be considered separately, causing the computational complexity to be unnecessarily large. With these findings, we stress that vehicular ad-hoc network (VANET) simulations should be based on the current geometry, i.e., a proper path loss model should be applied depending on whether the V2V communication is blocked or not by other vehicles or buildings.

City-level urban form and traffic safety: A structural equation modeling analysis of direct and indirect effects

While most existing studies have examined the impact of the community- and street-level built environment on traffic safety, few have provided empirical evidence on the associations between urban form characteristics and traffic safety at the city level. To this end, this article first created a detailed list of 23 variables to measure city-level urban form of 100 major Urban Areas (UAs) in the United States and then applied factor analysis to construct five latent variables which describe urban form. Factor analysis is also used to define mediator variables reflecting citywide transportation network features and dependent variable of traffic safety. Structural Equation Modeling (SEM) is then used to investigate how city-level urban form, directly and indirectly (through mediators of transportation network features), affects traffic safety. Based on the statistical results, urban traffic is safer in UAs with more uniform job-housing balance among their different tracts, more polycentric design, and less low-density sprawl. In addition to spatial variation in employment and urban density that have significant direct effect on traffic safety, improving transportation network connectivity and increasing the supply of public transit facilities and upper-level transport infrastructures can decrease traffic fatalities indirectly, through encouraging the use of non-driving transport modes. It is estimated that a 10% increase in urban density as well as a 10% increase in even spatial distribution of employment can reduce the rate of fatal crashes by >15%, on average. These findings demonstrate the importance of incorporating city-level land-use policies into the planning practices, in terms of traffic safety.

О необходимости дополнения норматива отвода ширины колеи

The current evaluation system of track geometry provides supervision of standards for graduation of the gauge and speed limits at excess of allowable values. At present maximum graduation of the gauge normalized in accordance with the standard operating Procedures for the current maintenance of railway track. This article discusses the shortcomings of the existing system of evaluation in terms of lateral track geometry. In order to overcome it, direction of improving current standards for estimating lateral track geometry is proposed and justified.On the basis of data on the track geometry parameters obtained from track measuring cars the analysis of interdependencies of lateral irregularity parameters for outer and inner rails in the curve was made using of the mathematical description of the parameters of rails lateral irregularities by identifying the length, amplitude and half-wave graduation. The presence of significant differences in the position of rails in the direction of the curves and larger lateral irregularities on the inner rail was estimated. The presence of patterns of length changes, amplitude and graduation of lateral irregularities is shown. Authors present results of the analysis of correlation parameters of lateral irregularities on the outer and inner rails in curved sections of the track. The presence of an average degree of correlation relationship of position of lateral position of outer and inner rails of curved sections is shown. The influence of the graduation of lateral irregularities on performance of rolling stock dynamics is given. Values of the graduation of lateral irregularities, unacceptable in terms of traffic safety, are established.

LED (Light-Emitting Diode) Road Lighting in Practice: An Evaluation of Compliance with Regulations and Improvements for Further Energy Savings

Light-emitting diode (LED) road lighting has been widely implemented in recent years, but few studies have evaluated its performance after installation. This study investigated whether LED road lighting complies with minimum regulations in terms of traffic safety and whether improvements for energy efficiency are possible. Average road surface luminance (L), overall luminance uniformity (Uo), longitudinal luminance uniformity (UI), power density (PD) and normalised power density (PN) were evaluated for 14 roads (seven designed for vehicular traffic and seven for pedestrians and bicycles). Energy savings were calculated as the percentage reduction to the minimum level of the existing lighting class or a lower lighting class and by applying a dimming schedule. The results showed that LED road lighting for vehicular traffic roads generally fulfilled the requirements, whereas that for pedestrian and bicycle roads generally corresponded to the lowest lighting class for L, and often did not meet the statutory requirements for Uo and UI. By adapting lighting levels to the minimum requirement of the existing lighting class or by dropping to a lower lighting class, vehicular traffic roads could save 6%–35% on L to lighting class M5 and 23%–61% on L to lighting class M6. A dimming schedule could lead to energy savings of 49%. There is little potential for savings on pedestrian and bicycle roads, except by implementing a dimming schedule. Thus, in general, for vehicular, pedestrian and bicycle roads, a dimming schedule can save more energy than can be achieved in general by reducing lighting class. Furthermore, since a dimming schedule can be adjusted to traffic intensity, any potential risk of compromising traffic safety is minimised.

DYNAMIC FEATURES OF STANDARD TANK CARS ON CURVED TRACK SECTIONS

[For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version)].ABSTRACT Nature of interaction of wheel sets of four-axle and eight-axle tank cars with rails when driving in curves of railway track is considered, including specifics of longitudinal and transverse elastic ties of wheel sets with bogie’s side frames. The results of dynamic performance studies (coefficient of dynamic addition of vertical forces on sprung weight and transverse frame force) of tank cars in curves with radii of 350 and 650 m are provided. It follows that eight-axle tank car design under the terms of traffic safety from the point of view of dynamics is at the same level as a four-axle one, therefore, can be used without restriction on all railways under the same rules of maintenance for undercarriages of tank cars of both types. Keywords: railway, theoretical mechanics, tank car, wheel sets, rails in curves, dynamic performance, elastic and frictional bonds, unextinguished transverse acceleration, coefficient of dynamic addition of vertical forces, frame force, comparative analysis. REFERENCES 1.Verigo, M. F.Interaction of track and rolling stock in curves of small radius and the fight against side wear of rails and wheel flanges [Vzaimodejstvie puti i podvizhnogo sostava v krivyh malogo radiusa i bor’ba s bokovym iznosom rel’sov i grebnej koljos]. Moscow, PTKB CP MPS publ., 1997, 207 p. 2. Anisimov, P. S. Methods of Evaluation of the Impact of Freight cars on the Track. World of Transport and Transportation, Vol.12, 2014, Iss.1, pp.24-32. 3.Vershinskiy, S.V., Danilov, V.N., Khusidov, V. D. The dynamics of the car [Dinamika vagona]. Moscow, Transport publ., 1991, 360 p. 4.Anisimov, P.S., Zhelnin, G.G., Kulikovskiy, B. S. Permissible speed of eight-axle tanks dimensions TC [Dopuskaemye skorosti dvizhenija vos’miosnyh cistern gabarita Tc]. Trudy MIIT, 1986, Iss.780, pp.10-24. 5.Anisimov, P.S., Grachiova, L. O. Tests of eight-axle tanks for BAM [Ispytanija vos’miosnyh cistern dlja BAMa]. Zheleznodorozhnyj transport, 1986, Iss.5, pp.35-36.

Microscopic cooperative traffic flow: calibration and simulation based on a next generation simulation dataset

The deployment of new emerging technologies, such as cooperative systems, allows the traffic community to foresee relevant improvements in terms of traffic safety and efficiency. Autonomous vehicles are able to share information about the local traffic state in real time, which could result in a better reaction to the mechanism of traffic jam formation. An upstream single-hop radio broadcast network can improve the perception of each cooperative driver within a specific radio range and hence the traffic stability. The impact of vehicle to vehicle cooperation on the onset of traffic congestion is investigated analytically and through simulation. A next generation simulation field dataset is used to calibrate the full velocity difference car-following model, and the MOBIL lane-changing model is implemented. The robustness of the calibration as well as the heterogeneity of the drivers is discussed. Assuming that congestion can be triggered either by the heterogeneity of drivers' behaviours or abnormal lane-changing behaviours, the calibrated car-following model is used to assess the impact of a microscopic cooperative law on egoistic lane-changing behaviours. The cooperative law can help reduce and delay traffic congestion and can have a positive effect on safety indicators.

What lessons can socioeconomic changes in Japan give to the transportation industry?

Currently, Japan is confronting several major socioeconomic changes, which in turn are the primary causes behind transportation issues surfacing in Japan. These changes in socioeconomics can be identified in the four categories of declining birthrate in an aging population, globalization, technological innovation, and improvements in standard of living. In private and public transportation, technological innovation may impact maintenance of the transportation infrastructure by complicating user behavior. Further, improvements in the standard of living foster expectations of profit from demand for tourism even though these expectations are fraught with issues created by globalization. In terms of traffic safety, strategic measures against accidents are expected, with flags raised regarding changes in human behavior due to technological innovation, and suggestions to aim measures toward bicycle transportation through improved standards of living. By sufficiently investigating these socioeconomic factors that color Japan today and the transportation issues that they cause, other countries that may witness similar experiences may learn important lessons.

Safety Impacts of Intervehicle Warning Information Systems for Moving Hazards in Connected Vehicle Environments

Driver inattentiveness is one of the critical factors that contribute to vehicle crashes. The intervehicle safety warning information system (ISWS) is a technology to enhance driver attentiveness by providing warning messages about upcoming hazards under the connected vehicle environments. A novel feature of the proposed ISWS is its capability to detect hazardous driving events, which are defined as moving hazards with a high potential to cause crashes. The study presented in this paper evaluated the potential effectiveness of the ISWS to reduce crashes and to mitigate traffic congestion. The study included a field experiment that documented actual vehicle maneuvering patterns of accelerations and lane changes, which were used to enhance the realism of simulation evaluations. Probe vehicles equipped with customized onboard units, which consisted of a GPS device, accelerometer, and gyro sensor, were used. A microscopic simulator, VISSIM, was used to simulate a driver's responsive behavior after warning messages were delivered. A surrogate safety assessment model was used to derive surrogate safety measures to evaluate the effectiveness of ISWS in terms of traffic safety. The results showed a reduced number of rear-end conflicts when the ISWS's market penetration rate (MPR) and the congestion level of the traffic conditions increased. The reduced number of rear-end conflicts was approximately 84.3%, with a 100% MPR under Level of Service D traffic conditions. Analysis of the standard deviation of speed showed that a reduction of 39.9% was achieved. The outcomes of this study could be valuable to derive smarter operational strategies for ISWS.

Evaluation of semi-actuated signals and pedestrian push buttons using a microscopic traffic simulation model

The typical geometry of many signalized intersections on national highways is that of a major street with a minor road of which traffic and pedestrian volumes are low in general, especially in rural areas. Such intersections generally show long green-lights for the through movements on the minor crossroad in order to serve pedestrian crossing time regardless of the volumes of pedestrians and vehicles. This research effort was initiated to solve this problem by introducing semi-actuated signals and pedestrian push buttons. To this end, this research effort evaluated the detailed effects of the introduction of semi-actuated signals and pedestrian push buttons using a calibrated microscopic traffic simulation model, VISSIM. This research effort evaluates three scenarios, including i) pretimed signal control in use at a selected test site (Scenario 1), ii) semi-actuated signal control (Scenario 2), and iii) semi-actuated signal control coupled with pedestrian push buttons (Scenario 3). From the results of evaluations through intensive simulation under diverse traffic conditions, the three scenarios showed a similar level of network-wide average delays. However, compared with Scenario 1, Scenario 2 showed 2.7% improvements on delay of a coordinated movement on average. In addition, compared with Scenario 1, Scenario 3 showed 13.0% improvements on average. Finally, Scenario 3 showed 10.5% improvements over Scenario 2. However, in terms of traffic safety, completely different results were found as follows. Scenario 1 showed the smallest frequency of traffic conflicts. Conclusively, the introduction of the semi-actuated signals coupled with pedestrian push buttons can increase the mobility on major streets by shifting unused green times from minor crossroads to the coordinated movements. However, more attention from traffic engineers is required when they introduce actuated signal control in terms of selecting actuated signal control parameters.

About Longitudinal Dynamics of Classical Passenger Trains during Braking Actions

There are presented and analyzed specific aspects regarding the main mechanic and pneumatic issues determining the in-train dynamic forces developed during braking actions. Particularities in case of passenger trains are highlighted, with the aim of proving that even in the case of short trains, fitted with UIC type P braking system, longitudinal dynamics can cause significant reactions whose effect cannot be neglected, both in terms of traffic safety and comfort. Numerical examples presented stand for this.

Modified Intelligent Driver Model for driver safety and traffic stability improvement

The Intelligent Driver Model (IDM) is an Adaptive Cruise Control (ACC) model which is widely used for longitudinal vehicle motion modeling. The IDM presents important advantages against the other ACC models which are the availability and the intuitive of its parameters. Nevertheless, it presents some drawbacks such us the exceeding of the real vehicle deceleration. Moreover, the IDM does not totally guarantee the traffic safety in case of accident scenario in terms of collision number. This paper deals with IDM modification to improve the driver safety and to respect the real vehicle capability. Considering the last two modifications and assuming that the driver should takes into account the tail vehicle behavior, a new IDM version is developed and tested with a microscopic traffic simulator in terms of string stabilization. Results show good performance in terms of traffic safety as well as the string stability.

A model to evaluate road traffic safety in Safe Communities (SC)

BackgroundTraffic is still the leading cause of death and disability in all around world and indeed SC Evaluation in terms of traffic safety is crucial.AimsTo set up a comprehensive model...

도로환경특성을 고려한 안전속도 산정에 관한 연구

PURPOSES : The causes of traffic accidents can be classified into the factors of users, vehicles, and driving environments. Traffic accidents result from the deficiency in single or combination of these three factors. The objective of this study is to define the hazardous sections of highway in terms of traffic safety considering these three factors. METHODS : The test drivers performed repeated driving on these sections. The drivers and passengers recorded the sections on which the driving was uncomfortable, and the speeds on the sections excluding the uncomfortable sections were used for the development of the model. RESULTS : The model is composed of three sub-models for each of the horizontal curve, tangent, and the section where the curve starts/ends. The safe driving behavior coefficients by the horizontal curvature were derived by comparing the maximum operating speeds at which the vehicle may slide or deviate and the speeds at which the drivers feel comfort. The safety speeds on tangent were derived by the length of tangent section considering the driver`s desired speeds under the traffic condition on which the drivers hardly influenced by the other vehicles. For the sections where the curve starts/ends, the driving behaviors were classified by the distances between the curves, and the safe acceleration/deceleration speeds were derived on which the drivers enter/exit the curve sections safely. CONCLUSIONS : Safety speed could then be regarded that the model suggested in this study may be useful to define the potentially hazardous section and contribute the improvement of safety.

Intelligent Environment-Friendly Vehicles: Concept and Case Studies

The concept of an intelligent environment-friendly vehicle (i-EFV) is proposed in this paper. It integrates three components, i.e., clean-energy powertrain, electrified chassis, and intelligent information interaction devices. By employing such technologies as structure sharing, data fusion, and control coordination, more comprehensive performances are achievable, in terms of traffic safety, fuel efficiency, and environmental protection. Based on its definition and configuration, some key technologies, including design for resource effectiveness, driving environment identification, and coordinated control, are studied. As a basic application, a platform of an intelligent hybrid electric vehicle (i-HEV), which incorporates a hybrid powertrain with adaptive cruise control, has been designed and implemented. Both simulation and experimental results demonstrated that the i-EFV performed better than a conventional vehicle.

A Bayesian assessment of the effect of highway bypasses in Iowa on crashes and crash rate

Introduction A common contention is that the construction of highway bypasses negatively impacts the economy of local communities by reducing pass-by traffic for businesses. However, as access to specific business' account records is limited, this impact is difficult to quantify. Another common contention is that bypasses contribute to a reduction in overall crashes in the community and in the surrounding areas. Even though a large number of bypasses have been constructed in the State of Iowa over the past several years, their actual impact in terms of traffic safety has not been quantified. Objectives This study seeks answers to the following questions: (a) Are bypasses in Iowa associated with a reduction in crash frequencies and crash rates on the bypassed highway? (b) Do bypasses in Iowa introduce a reduction of overall crash frequencies and rates or do they merely shift crashes from the highways through the communities to the bypasses with no significant overall reduction? Method We obtained crash information from the Iowa DOT at 19 sites on which a bypass was constructed sometime during the past 23 years. We also obtained the same information at six sites used as comparison sites on which no bypasses were constructed at least until 2005. We them employed a Bayesian approach to estimating the association between the construction of the bypass and crash rates, while also accounting for other factors. Results The construction of bypasses in Iowa is associated with a significant increase in traffic safety both on the main road through town and on the combined main road and bypass roadway.

Analysis of Design Solutions in the Objects of Gravel Roads Paving Programme in Terms of Traffic Safety

Recently, the accident rate in Lithuania has been among the highest in Europe. The experience of implementing a Gravel Roads Paving Program (GRPP) shows that accident rates have been increasing on the reconstructed road sections. This enables to make an assumption that design solutions taken on the reconstructed gravel roads may be not suitable in terms of traffic safety, since, currently, attempts are made to design the least possible deviation of the project road axis from the existing road axis. The paper evaluates the quality of design solutions in terms of traffic safety in the objects of GRPP through the use of the design method applied in West European countries, which is based on safety criteria and enables to evaluate traffic safety not only on existing but on the designed 2-lane suburban roads. The paper investigates the road plan solutions in the objects of the GRPP. Dangerous road sections on reconstructed/being reconstructed sections were identified, and analysis of the real or predictable accident rates on these sections was carried out.

Analysis of a Bridge Structure and its Wind Barrier under Wind Loads

In this paper a study of wind barrier efficiency in terms of traffic safety is analyzed. A novel approach to bridge structures design is represented, where relevant traffic safety issues are incorporated into an early stage of design procedures. The numerical procedure based on standard turbulence model is applied to calculate resulting wind forces on the vehicle of arbitrary geometry. The effect of wind barriers geometry placed on both sides of the viaduct on resulting vehicle wind forces is analyzed. Used numerical procedure has also been experimentally verified in a wind tunnel laboratory. Complex multibody models that could be used to analyze vehicle handling and riding dynamic are represented. Further, vehicle models are used to show how resulting wind forces could affect vehicle dynamic and traffic safety issues. Relevant traffic safety situations are considered and discussed for particular wind barrier.

SIMULATION AND EVALUATION OF “INTELLIGENT CRUISE CONTROL”

Abstract “Intelligent Cruise Control” (ICC) is one of the PROMETHEUS systems for which short-term implementation has been suggested. The German PRO-GEN Group has worked intensively on the development and evaluation of ICC during the last few years. The functions of ICC have been specified in cooperation with the automotive industry concerned. The system has been assessed in terms of traffic safety, transport efficiency and environmental pollution, based on microscopic traffic simulations. The assessment results show considerable safety benefits, whereas the decrease in transport efficiency is negligible.