Auditory detection and localization of approaching vehicles

Pedestrians must use a variety of cues when making safe decisions, many of which require processing of auditory information. We examined detection and localization of approaching vehicles using auditory cues. 50 adults ages 18–49 were presented with actual sounds of vehicles approaching at 5, 12, 25, and 35 mph. Three indices were of interest: the distance at which vehicles were detected, participants’ decision regarding the direction from which vehicles were approaching, and their determination of the vehicles’ arrival at their location. Participants more easily detected vehicles moving at higher speeds and vehicles approaching from the right. Determination of the direction of approach reached 90% accuracy or better when vehicles were traveling at, or greater than, 12 mph, and were more approaching from the right. Determination of vehicle arrival deteriorated significantly as speeds increased. Implications of the use of auditory cues in pedestrian settings, and future directions, are discussed.     

Pedestrians, vehicles, and cell phones

With cellular phones and portable music players becoming a staple in everyday life, questions have arisen regarding the attentional deficits that might occur when such devices are used while performing other tasks. Here, we used a street-crossing task in an immersive virtual environment to test how this sort of divided attention affects pedestrian behavior when crossing a busy street. Thirty-six participants navigated through a series of unsigned intersections by walking on a manual treadmill in a virtual environment. While crossing, participants were undistracted, engaged in a hands free cell phone conversation, or listening to music on an iPod. Pedestrians were less likely to successfully cross the road when conversing on a cell phone than when listening to music, even though they took more time to initiate their crossing when conversing on a cell phone (∼1.5 s). This success rate difference was driven largely by failures to cross the road in the allotted trial time period (30 s), suggesting that when conversing on a cell phone pedestrians are less likely to recognize and act on crossing opportunities.     

Speed estimation of vehicles approaching an intersection: a digital image processing method

Abstract

Most severe car accidents that occur in urban environments involve side impacts at street intersections, even at those regulated with traffic lights. Hence, it is very common to implement a small delay since one road changes to red until the other road changes to green. This delay is intended to avoid accidents in which a vehicle decides to go through the intersection after the sequence green–yellow–red is started, underestimating the time required to overtake the intersection. A better approach is to adjust the delay dynamically, depending on the speed of the vehicles approaching to the intersection. Using the dynamic approach, it is possible to improve traffic flow by reducing unnecessary delays, and to improve safety by applying longer delays when needed. This paper proposes a speed estimation method based on digital image processing of pictures taken with wireless cameras installed on top of existing traffic lights. The algorithm finds a vehicle in two consecutive images (either in day or night condition) and computes its speed by correlation. When a traffic light turns red, the systems estimates the speed of the cars approaching and decides to change the other road to green immediately, or to wait until it is safe to do so. The system was tested with real traffic flow at a street located in the city of Talavera de la Reina, Spain, with vehicles at different speeds. The image processing method proved to be accurate for this application, and adding the advantage of low cost equipment and easy installation results in a very attractive solution.     

食品包装技术及发展趋势

介绍了食品工业常用的包装技术及其相关的技术设备,总结了包装技术的特点。讨论了食品包装的发展趋势。     

Validation of virtual reality as a tool to understand and prevent child pedestrian injury

In recent years, virtual reality has emerged as an innovative tool for health-related education and training. Among the many benefits of virtual reality is the opportunity for novice users to engage unsupervised in a safe environment when the real environment might be dangerous. Virtual environments are only useful for health-related research, however, if behavior in the virtual world validly matches behavior in the real world. This study was designed to test the validity of an immersive, interactive virtual pedestrian environment. A sample of 102 children and 74 adults was recruited to complete simulated road-crossings in both the virtual environment and the identical real environment. In both the child and adult samples, construct validity was demonstrated via significant correlations between behavior in the virtual and real worlds. Results also indicate construct validity through developmental differences in behavior; convergent validity by showing correlations between parent-reported child temperament and behavior in the virtual world; internal reliability of various measures of pedestrian safety in the virtual world; and face validity, as measured by users' self-reported perception of realism in the virtual world. We discuss issues of generalizability to other virtual environments, and the implications for application of virtual reality to understanding and preventing pediatric pedestrian injuries.     

Performance measures and input uncertainty for pedestrian crossing exposure estimates

Pedestrian safety performance measures often use estimates of annual crossing exposure as inputs—but relatively little information exists on the uncertainty associated with these inputs. This research considers two sources of temporal information for expanding short-term counts: (1) a composite of pedestrian counts from other cities, and (2) local vehicle counts. A database of pedestrian flows from video review covering 12 months and including over 350,000 pedestrian observations provides a known reference annual volume and a set of short-term counts for expansion and testing.     

Stop versus yield on pedestrian-involved fatal crashes in the United States

In an effort to improve pedestrian safety, several states in the United States changed their pedestrian laws by changing the requirement that drivers yield to pedestrians in crosswalks to a requirement that drivers stop for pedestrians in crosswalks. This study examined whether this change had an effect on pedestrian safety in the United States, with its focus on low-speed roads. To examine the association between changes in pedestrian laws and changes in pedestrian-involved fatal crashes, three approaches were employed: before–after analysis, time-series analysis, and cross-sectional analysis. Pedestrian-involved fatal traffic crashes on low-speed roads were extracted from the U.S. national fatal crash database, the Fatality Analysis Reporting System (FARS), from 1980 through 2005. This study found no statistically significant reduction in pedestrian-involved fatal crashes attributable to changes in the laws, yet this finding is not definitive because of study limitations such as the omission of relevant exposure data.     

The development of an automatic method of safety monitoring at Pelican crossings

This paper reports on the development of a method for automatic monitoring of safety at Pelican crossings. Historically, safety monitoring has typically been carried out using accident data, though given the rarity of such events it is difficult to quickly detect change in accident risk at a particular site. An alternative indicator sometimes used is traffic conflicts, though this data can be time consuming and expensive to collect. The method developed in this paper uses vehicle speeds and decelerations collected using standard in situ loops and tubes, to determine conflicts using vehicle decelerations and to assess the possibility of automatic safety monitoring at Pelican crossings. Information on signal settings, driver crossing behaviour, pedestrian crossing behaviour and delays, and pedestrian-vehicle conflicts was collected synchronously through a combination of direct observation, video analysis, and analysis of output from tube and loop detectors. Models were developed to predict safety, i.e. pedestrian-vehicle conflicts using vehicle speeds and decelerations.     

A mixed generalized ordered response model for examining pedestrian and bicyclist injury severity level in traffic crashes

This paper proposes an econometric structure for injury severity analysis at the level of individual accidents that recognizes the ordinal nature of the categories in which injury severity are recorded, while also allowing flexibility in capturing the effects of explanatory variables on each ordinal category and allowing heterogeneity in the effects of contributing factors due to the moderating influence of unobserved factors. The model developed here, referred to as the mixed generalized ordered response logit (MGORL) model, generalizes the standard ordered response models used in the extant literature for injury severity analysis. To our knowledge, this is the first such formulation to be proposed and applied in the econometric literature in general, and in the safety analysis literature in particular.

The MGORL model is applied to examine non-motorist injury severity in accidents in the USA, using the 2004 General Estimates System (GES) database. The empirical findings emphasize the inconsistent results obtained from the standard ordered response model. An important policy result from our analysis is that the general pattern and relative magnitude of elasticity effects of injury severity determinants are similar for pedestrians and bicyclists. The analysis also suggests that the most important variables influencing non-motorist injury severity are the age of the individual (the elderly are more injury-prone), the speed limit on the roadway (higher speed limits lead to higher injury severity levels), location of crashes (those at signalized intersections are less severe than those elsewhere), and time-of-day (darker periods lead to higher injury severity).     

The role of the built environment in explaining relationships between perceived and actual pedestrian and bicyclist safety

While the conventional approach to safety planning has emphasized crash analysis with police-reported crash information, transportation professionals increasingly recognize the importance of proactively identifying potential crash risk and considering environmental characteristics. In a proactive approach, individuals’ perception of crash risk provides important information in identifying potential crash risk. As built environment characteristics influence the levels of pedestrian and bicycle safety, this study examined how perceived and actual crash risk are related with each other and with respect to built environmental characteristics. Our results showed that residents who live in low density-single residential neighborhoods are more likely to perceive their neighborhood as dangerous relative to residents of compact, mixed-use neighborhoods even though the latter exhibited higher actual crash rates. The results of path analyses confirmed that a simultaneous but opposite relationship exists between perceived and actual crash risks. Our results indicate that higher actual crash risk increases perceived crash risk, while higher perceived crash risk is negatively associated to actual crash rates. Consequently, low density and non-mixed land uses increase individuals perception of crash risk, and increased perception of risk and unfriendly environment for pedestrian and bikers reduces actual crash rates as a result of behavioral changes. From a policy standpoint, more attention and proactive interventions are desirable in suburban areas beyond the areas with high crash rates, as some of these areas have high-perceived risks.     

Higher-order-statistics-based detection of vehicles in still images.

We present a statistical pattern recognition scheme for detecting vehicles in still images. The methodology involves pattern classification using higher-order statistics (HOS) in a clustering framework. The proposed method approximately models the unknown distribution of the image patterns of vehicles by learning HOS information about the vehicle class from sample images. Given a test image, statistical information about the background is learned "on the fly." An HOS-based decision measure derived from a series expansion of the multivariate probability density function in terms of the Gaussian function and Hermite polynomials is used to classify test patterns as vehicles or otherwise. Experimental results on real images with cluttered background are given to demonstrate the performance of the proposed method. When tested on real aerial images, the method gives good results, even for complicated scenes. The detection rate is found to be quite good, while the false alarms are very few. The method can serve as an important step toward building an automated traffic monitoring system.     

Age-related differences in street-crossing decisions: the effects of vehicle speed and time constraints on gap selection in an estimation task

Two experiments were conducted to study how age affects street-crossing decisions in an estimation task, with particular emphasis on how oncoming vehicle speed and a time constraint influence the time gap deemed acceptable for crossing. Experiment 1 showed that when there was a time constraint, all age groups selected a shorter time gap for the higher speed. This was associated with a large number of missed opportunities for the low speed and many unsafe decisions for the high speed. In the second experiment, which had no time constraint, young pedestrians operated in a constant-time mode regardless of speed, whereas older pedestrians accepted shorter and shorter time gaps as speed increased. The results seem to indicate that the effect of speed is due to a mixed operating mode of participants, whose decisions may be based on either time or vehicle distance, depending on the task requirements and on the participant's own ability to meet those requirements.     

爆破振动对临近尾矿坝的安全影响分析

为了探求采场爆破对临近尾矿库坝体稳定性的影响程度,进行了4次不同爆破参数采场爆破实验,并对爆破实验的振动影响进行监测。采用萨道夫斯基爆破振动经验公式计算爆破振动速度,为了得到更准确、更可靠的k、α值,对监测数据进行线性拟合,变换出适合该矿的萨道夫斯基爆破振动公式;根据该公式对不同振动速度控制标准下的起爆炸药量和最小安全距离关系进行了预测,对不同振动速度控制标准下的安全距离与允许最大起爆药量进行了估算。研究结果对矿山露天爆破最大药量和安全距离的选取具有一定的现场指导意义。     

昆明市儿童行人交通安全行为研究

采用简单随机抽样的方法对昆明市204名儿童进行了交通安全认知和交通习惯调查。结果表明,儿童整体上获得交通安全知识媒介偏少,以5种媒介为参考,其均值为2．8333,且56．4％的儿童交通安全知识首先从父母那获得。儿童交通安全行为与儿童交通安全意识、儿童交通危险意识、儿童交通安全态度、父母交通行为显著相关。儿童交通安全行为与儿童交通安全意识和儿童交通安全态度呈二元线性关系。本研究结果可为提高儿童行人交通安全行为的方法选择提供参考。     

The risk of pedestrian injury and fatality in collisions with motor vehicles, a social ecological study of state routes and city streets in King County, Washington

This study examined the correlates of injury severity using police records of pedestrian–motor-vehicle collisions on state routes and city streets in King County, Washington. Levels of influence on collision outcome considered (1) the characteristics of individual pedestrians and drivers and their actions; (2) the road environment; and (3) the neighborhood environment. Binary logistic regressions served to estimate the risk of a pedestrian being severely injured or dying versus suffering minor or no injury.Significant individual-level influences on injury severity were confirmed for both types of roads: pedestrians being older or younger; the vehicle moving straight on the roadway. New variables associated with increased risk of severe injury or death included: having more than two pedestrians involved in a collision; and on city streets, the driver being inebriated.Road intersection design was significant only in the state route models, with pedestrians crossing at intersections without signals increasing the risk of being injured or dying.Adjusting for pedestrians’ and drivers’ characteristics and actions, neighborhood medium home values and higher residential densities increased the risk of injury or death. No other road or neighborhood environment variable remained significant, suggesting that pedestrians were not safer in areas with high pedestrian activity.     

Factors contributing to driver choice after hitting a pedestrian in Japan

In Japan, where pedestrian deaths account for a third of road traffic fatalities, 7.4% of victims die from hit-and-run accidents. To identify determinants for drivers considering leaving an accident scene after hitting a pedestrian, environment-related, driver-related, and pedestrian-related factors were examined using Japanese national police data. Results generally confirmed the conceptual framework of previous studies, which examined hit-and-run behavior based on a classic economic cost–benefit approach. However, results suggest that effects of road-related factors and harsher legal punishments have limited influence for reducing hit-and-run likelihood after a driver hits a pedestrian. Measures to prevent hit-and-run accidents are presented herein.     

软海底强干扰环境下的集矿车自适应定位

针对海底集矿车长基线声学定位受工作噪声干扰以及航位推算精度受打滑干扰等问题,基于附加打滑参数的履带车运动学模型和根据湖试数据对导航系统过程噪声与测量噪声的描述,并提出了一种自适应时滞扩展卡尔曼滤波方法.该方法利用新息序列实现噪声统计特性自适应,然后考虑测量数据时延带来的影响,通过卡尔曼滤波器将长基线定位信息与航位推算信息进行融合,得到集矿车的位置估计.仿真结果证实,该自适应卡尔曼滤波器能有效地适应过程噪声与测量噪声统计特性的变化,比常规卡尔曼滤波器具有更好的海底集矿车定位效果.     

Gender differences in pedestrian rule compliance and visual search at signalized and unsignalized crossroads

Male pedestrians are over-represented in road crashes. Among pedestrians, males violate more rules than females do. For now, it is not known whether gender differences in pedestrian behaviors only concern rule compliance. The objective of this study was to explore gender differences in pedestrian rule compliance and in gaze targets before and during crossing. 400 adult pedestrians were observed at two signalized and two unsignalized crossroads, using a taxonomic observation grid which detailed 13 behavioral categories before, during and after crossing. The results show that the temporal crossing compliance rate is lower among male pedestrians but spatial crossing compliance does not differ between genders. Furthermore, different gaze patterns emerge between genders before and during crossing, notably as women particularly focus on other pedestrians during these two periods whereas men focus on vehicles. Moreover, females’ gazes vary with the type of crossroads, but males’ gazes do not. Spatial crossing compliance and gaze targets are furthermore modulated by the crossroad configuration. These results are discussed in terms of pedestrian visual strategy and compliance.     

Influence of approaching tram on behaviour of pedestrians in signalised crosswalks in Poland

Research done in two Polish cities has uncovered an influence of an approaching tram on pedestrian behaviour. The measurements were done by counting pedestrians waiting for a green signal, crossing on red signal safely, or crossing on red signal taking a risk of being hit by a car, differentiating between pedestrians attempting to board a public transport vehicle and other pedestrians. It was expected, that pedestrian behaviour might be influenced by traffic control predictability, therefore two cities were chosen for the task: Wroc?aw with fixed time traffic control and Poznań with a majority of traffic responsive traffic signals. Data from the measurements was compared in order to find behaviour patterns – the comparison led to a conclusion, that an attempt to get on board of an incoming public transport vehicle can be a major cause for pedestrians to violate a red signal, including an increase of unsafe behaviour. These pedestrians may provoke other pedestrians to cross on a red signal. On the other hand if traffic control guarantees boarding the public transport vehicle, passengers-to-be may be even more obedient than other pedestrians.