Assessment of distracted pedestrian crossing behavior at midblock crosswalks

Risk of pedestrian-vehicle crashes increased with distraction of pedestrians at roadway crossings. Aims of the study included analysing distracted pedestrian crossing behavior, identifying factors that influence pedestrian crossing speed at a midblock crosswalk, and determining the influence of road cross-section (RCS) on pedestrian walking speed.Three cities in Oregon State in the USA were included in the study: Corvallis, Albany, and Eugene. A combination of digital video and researcher field notes were used to obtain the data at each site. A total of 1045 pedestrian crossings from 23 midblock crossings were observed and analysed to determine the association of distraction type, road cross-section, and other in situ factors with pedestrian walking speed. Data analysis was conducted in two stages. First, the effect of each distraction type (looking at a handheld device, talking on a cell phone, wearing headphones, walking in a pair, walking in a group, and other distractions) on the pedestrian walking speed was examined. The results showed that average walking speed was 4.8 ft./s (1.46 m/s). Pedestrians walking with headphones crossed more quickly (0.91 ft./s) (0.28 m/s) than those with no distractions (5.14 ft./s) (1.57 m/s). In addition, talking on a cell phone was not significantly correlated with walking speed. Moreover, the other four distraction types were associated with decreasing the walking speed by 0.29 ft./s (0.09 m/s) to 0.83 ft./s (0.25 m/s). Second, the influence of pedestrian distraction, crosswalk configuration, land use, compliance rate, and pedestrian demographics on the pedestrian walking speed were examined in this study. Findings indicated that distracted pedestrian in two road cross-sections would require more crossing time than an elderly pedestrian. Pedestrian safety is a key concern in transportation research, and improved understanding of the factors contributing to pedestrian fatalities could enable safer roadways to be designed.     

Injury analysis of pedestrians in collisions using the pedestrian deformable model

Vehicle safety has become the most important issue in automobile design. However, all efforts to improve safety devices focus on enhancing safety features for occupants. Notably, pedestrians are the second largest category of motor vehicle deaths, after occupants, and account for about 13 percent of motor vehicle deaths. It is essential to design pedestrian-friendly vehicles and pedestrian protection systems to reduce pedestrian fatalities and injuries. To effectively assess pedestrian injuries resulting from vehicle impact, a deformable pedestrian model must be developed for vehicle-pedestrian collision analysis. This study constructs a pedestrian-collision numerical model based on LS-DYNA finite element code. To verify the accuracy of the proposed deformable pedestrian model, experimental data are used in the pedestrian model test. This study applies the proposed model to analyze the dynamic responses and injuries of pedestrians involved in collisions. The modeled results can help assess vehicle pedestrian friendliness and assist in the future development of pedestrian-friendly vehicle technologies.     

Optimizing the shape of a bumper beam section considering pedestrian protection

This paper presents a design technique to optimize the shape of a vehicle bumper beam that satisfies both the safety requirements for a front rigid-wall impact and the regulations protecting pedestrians from lower leg injuries caused by bumper impacts. An intermediate response surface modeling (IRSM) technique was introduced to approximate the non-linear force-displacement curves obtained from the front impact analysis of a vehicle bumper. The accuracy of the IRSM model was tested by comparing its results with those of the non-linear finite element analysis. The maximum displacement error between the two models did not exceed 3%. Using pedestrian impact analyses based on the experimental arrangement of the Plackett-Burman design, the approximate functions describing the response values acting on the lower legs were calculated. The shape of the bumper beam was optimized by integrating the IRSM with the force-displacement model and the approximate functions on lower leg impact. The optimization results satisfied safety regulations on the maximum allowable displacement of the vehicle bumper, and also the regulations protecting pedestrians from lower leg injuries caused by bumper impacts.     

Mitigating the effect of impact loading on a vehicle using an essentially nonlinear absorber

The aim of this study is to investigate the ability of an essentially nonlinear vibration absorber to mitigate the large accelerations transmitted to a passenger compartment of a vehicle which is subjected to shock-type transient loading at the chassis. For such problems, the induced vibration typically attains its maximum value shortly after the application of the loading; thus, it may be impossible to dissipate a major portion of the input energy prior to the occurrence of the peak response. Here, a class of absorbers possessing a form of discontinuous essential stiffness nonlinearity is employed to achieve the desired mitigation. In this paper, we apply a single vibro-impact (VI) absorber to the chassis and examine whether the resulting energy transfer mechanism is an effective way to reduce the peak value of the inertial force measured at the passenger compartment. The influence of the absorber parameters is first studied based on a practical impulsive force, and the optimal design of the absorber is then obtained. Next, an asymmetric clearance arrangement of the absorber is suggested to facilitate the mitigation. Finally, an impulsive acceleration excitation is applied to the system to examine the robustness and efficacy of the optimised absorber. Results of numerical simulations demonstrate that a properly designed VI absorber can significantly decrease the maximum inertial force at the passenger compartment, generated by external impulsive excitations.     

Development of a new sound metric for impact sound in a passenger car using the wavelet transform

Vehicles can experience impacts due to harsh road conditions. Contact with an uneven road surface causes vehicles to vibrate, which generates a loud impact sound. The attenuation of such noise is important because car passengers may complain about the impact noise. However, perfect removal of impact noise is not possible because most of it is caused by external conditions. More research is needed on the objective attributes of impact noise; however, the problem of impact noise is not a simple matter because impact noise is transient in nature and reaches a high level instantaneously. In this paper, a new objective attribute of impact noise is designed using the wavelet transform, which is appropriate for analyzing nonstationary signals, such as an impact signal. The usefulness of the new objective attribute, which is a sound metric, is examined by comparing the mean subjective ratings for real impact noise in passenger cars. The new sound metric has better correlation with the mean subjective rating than currently existing sound metrics.     

Model-based analysis of the mechanical subsystem of an air brake system

Most commercial vehicles such as buses and trucks use an air brake system, often equipped with an S-cam drum brake, to reduce their speed and/or to stop. With a drum brake system, the clearance between the brake shoe/pad and the brake drum may increase because of various reasons such as wearing of the brake shoe and/or brake drum and drum expansion caused by high heat generation during the braking process. Hence, to ensure proper functioning of the brake system, it is essential that the clearance between the brake shoe and the brake drum is monitored. In this paper, we present a mathematical model for the mechanical subsystem of the air brake system that can be used to monitor this clearance. This mathematical model correlates the push rod stroke transients and the brake chamber pressure transients. A kinematic analysis and a dynamic analysis of the mechanical subsystem of the air brake system were performed, and the results are corroborated with experimental data.     

Measuring the impact of urban policies on transportation energy saving using a land use-transport model

Various projects all over the world are attempting to build smart cities in hopes of achieving energy-efficient and livable communities, but most of them are aiming to fulfill their goals technologically. However, the energy efficiency and livability of a city are affected by not only these technological factors but also urban structures that encompass residential areas, offices, transportation networks, and other facilities. Urban policies intervene in transportation and land-use conditions and thereby change how citizens consume energy and go about their daily lives as the actors in the urban system alter their behavior. This means that energy efficiency and quality of life share close ties. Assessments of urban policies thus need to consider the reactions of actors to the intervention.     

Multivariate modeling of pedestrian fatality risk through on the spot accident investigation

Pedestrians are the most vulnerable users of public roads and represent one of the largest groups of road casualties; their death rate around the world due to vehicle-pedestrian collisions is high and tending to rise. In Spain, as in other countries of the European Union, steps have been taken to reduce the number and consequences of such accidents, with encouraging results in recent years. A key to countering this concern is the accident research activity that has obtained remarkable achievements in different fields, especially when multidisciplinary approaches are taken. This paper describes the development of a multivariate model that is able to detect the most influential parameters on the consequences of vehicle-pedestrian collision and to quantify their impact on pedestrian fatality risk. First, an accident database containing detailed information and parameters of vehicle-pedestrian collisions in Madrid has been developed. The accidents were investigated on the spot by INSIA accident investigation teams and analyzed using advanced reconstruction techniques. The model was then developed with two components: (1) a classification tree that characterizes and selects the explanatory variables, identifying their interactions, and (2) a binary logistic regression to quantify the influence of each variable and interaction resulting from the classification tree. The whole model represents an important tool for identifying, quantifying and predicting the potential impact of measures aimed at reducing injuries in vehicle-pedestrian collisions.     

Estimation of left-turning vehicle maneuvers for the assessment of pedestrian safety at intersections

Improving pedestrian safety at intersections remains a critical issue. Although several types of safety countermeasures, such as reforming intersection layouts, have been implemented, methods have not yet been established to quantitatively evaluate the effects of these countermeasures before installation. One of the main issues in pedestrian safety is conflicts with turning vehicles. This study aims to develop an integrated model to represent the variations in the maneuvers of left-turners (left-hand traffic) at signalized intersections that dynamically considers the vehicle reaction to intersection geometry and crossing pedestrians. The proposed method consists of four empirically developed stochastic sub-models, including a path model, free-flow speed profile model, lag/gap acceptance model, and stopping/clearing speed profile model. Since safety assessment is the main objective driving the development of the proposed model, this study uses post-encroachment time (PET) and vehicle speed at the crosswalk as validation parameters. Preliminary validation results obtained by Monte Carlo simulation show that the proposed integrated model can realistically represent the variations in vehicle maneuvers as well as the distribution of PET and vehicle speeds at the crosswalk.     

Bumper optimum design using the dynamically equivalent beam under various impact conditions

Nowadays it is required for the bumper system to meet the various impact conditions simultaneously; barrier impact, IIHS (Insurance Institute for Highway Safety) bumper impact and pedestrian impact. Firstly, dynamically equivalent bumper beam models were developed for each impact condition and its accuracy was verified by nonlinear finite element analysis result. Dynamically equivalent pedestrian impact beam model was developed by using the equivalent forces of bumper beam and stiffeners. Pedestrian bending angle was obtained by using this equivalent pedestrian beam model. By combining these equivalent beam models, bumper optimum design program was developed. In this optimum design program, direct search method was used for the optimization algorithm. To verify the accuracy of this optimum design program, a nonlinear finite element result was used. By using this optimum design program, it can be secured the bumper impact performances in an early design stage and it will be also contributed to reduce the design time and test costs.     

Evaluating the effects of external factors on pedestrian violations at signalized intersections (a case study of Mashhad,Iran)

One of the most critical reasons for accidents involving pedestrians in signalized urban intersections is their violations regarding running red lights. Therefore, studying the essential factors in this issue is of interest to researchers. This research aims to evaluate the external factors affecting the pedestrians' violation, specifically, factors regarding the geometrical design and traffic situation. Cameras recorded the behavior of 1590 pedestrians in 10 crosswalks of 6 intersections in Mashhad. Afterward, the effect of 12 distinct variables for each pedestrian was assessed. To analyze the data, SPSS was used in combination with binary logistic regression. Out of the nine variables participated in the model, “traffic volume”, “the number of violators”, “length of the crosswalk”, “red light duration”, and “physical movement problems” affect the pedestrians' decision to comply with or violate a red light. The analysis shows that with an increasing number of vehicles, the probability of violation would reduce by 9.5%. Moreover, if the number of other violating pedestrians grows, the probability of violation would increase significantly. The increase of one unit in “length of the crosswalk”, would result in a violation reduction of 13.9%. Also, if the pedestrian suffers from physical disabilities, the probability of violation decreases by 78.6%. On the other hand, the growth of one unit in “red light duration” would increase the violations by pedestrians 2.2%.     

针对行人保护头部仿真分析中雨刮臂的接触设置研究

利用计算机进行有限元仿真分析,在汽车行人保护性能开发过程中有着广泛的应用。对于行人保护建模来说,风挡玻璃区域应按照实际情况对玻璃进行准确建模,然而对于风挡玻璃与雨刮器采用以往的接触设置,雨刮臂与玻璃产生穿透现象。因此为了解决穿透问题,准确模拟出其实际运动关系,对于雨刮臂与风挡玻璃之间的接触设置研究是非常有必要的。     

Effects of the bumper stiffness characteristics on the pedestrian head injuries and the lower extremities injuries;

The effect of bumper stiffness characteristics on the pedestrian head and lower extremity injuries was investigated by using a vehicle Finite Element (FE) analysis model of the National Highway Traffic Safety Administration (NHTSA) of the USA. Some bumper stiffness curves for 20, 40, and 60 km/h crash speeds were obtained by the FE method. The effects of bumper stiffnesses of 0~1.27 MN /m on pedestrian head and lower extremity injuries were conducted by using a multi-body simulation method. The results show that different bumper stiffnesses have almost no effect on the overall kinematic response of pedestrians, but have an extremity effect on the injuries for pedestrian head and lower limb, especially for lower limb injuries. The pedestrian's head maximum contact force is 4.28 kN and 4.26 kN respectively, and the pedestrian's lower leg maximum contact force is 3.94 kN and 9.36 kN respectively, at the stiffness of the bumper contact force-deformation curve corresponding to 20 km/h and 60 km/h. Therefore, the risk of pedestrian lower limb injury increases with the increase of bumper stiffness. © 2023 Authors. All rights reserved.     

Assessment of an engine cylinder head-block joint using finite element analysis

An engine cylinder head-block joint is a gasketed, bolted joint. Assessment of sealing performance and fatigue durability of the joint during engine development relies entirely on the engine dynamometer test because the rig test cannot mimic the engine run condition and finite element analysis employs gasket and bolt models that are too simple to provide the stress data for fatigue assessment. This paper introduces finite element-based assessment of the gasket and the bolt and a model that improves the analysis accuracy without increasing computation time. Experimental data for the deformation of joint members under thermo-mehanical load are presented to demonstrate the accuracy of the model.     

Macroscopic analysis on the frequency and severity of pedestrian crashes on National Roads in Metro Manila,Philippines

Pedestrians are the most vulnerable road users; thus, understanding the primary factors that lead to pedestrian crashes is a chief concern in road safety. However, owing to the limitations of crash data in developing countries, only a few studies have evaluated the comprehensive characteristics of pedestrian crashes, specifically on different road types. This study attempted to develop pedestrian crash frequency and severity models on national roads by using the road characteristics and built environment parameters, based on the road crash data (2016–2018) that involved pedestrians in Metro Manila, Philippines. Remarkable findings included primary roads, presence of footbridges, road sections with bad surface conditions, and increased fractions of commercial, residential, and industrial roads, which exhibited a greater likelihood of pedestrian crashes. Crashes involving elderly pedestrians, heavier vehicles, late-night hours, fair surface conditions, and open spaces were associated with increased likelihoods of fatal outcomes. Essentially, this study provides a macroscopic perspective in understanding the factors associated with the severity and frequency of pedestrian crashes, and it would aid the authorities in identifying proper countermeasures.