Evaluation of pedestrian crossing speed change patterns at unprotected mid-block crosswalks in India

The pedestrian crossing speed is one of the important factors in pedestrian crossing facility design.Research studies have shown that the pedestrian crossing speed is influenced by availability of green time at signalized crosswalks and pedestrian characteristics such as gender and age.However,the effects of vehicular time gap and additional pedestrian behavioural characteristics on pedestrian crossing speed patterns have not been examined at unprotected(un-signalized)mid-block crosswalks.The present study examines the pedestrian crossing speed change patterns considering the effect of vehicular time gap and pedestrian behavioural characteristics such as rolling behaviour,path change,etc.,at selected unprotected mid-block crosswalk locations under mixed traffic conditions in India.Video graphic survey has been conducted at eight selected unprotected mid-block crosswalk locations in Mumbai City for two to three hours duration during normal weather conditions.The data was mined using AVS video editor software,and the extracted data includes pedestrian speed,pedestrian characteristics(gender and age),pedestrian behaviour(rolling behaviour,path change,etc.),vehicle characteristics(type and speed of the vehicle)and traffic characteristics.Pedestrian crossing speed change patterns(whether pedestrian is changing speed or not while crossing a road)was considered as a binary variable and a logistic regression model was developed with vehicular gaps and other pedestrian behavioural characteristics as independent variables.The results revealed that there is a reduction in pedestrian crossing speed change behaviour with an increase in vehicular gap size at unprotected mid-block crosswalks.The younger pedestrians have more probability of exhibiting crossing speed change patterns as compared to the elderly pedestrians at mid-block crosswalks.Further,it is identified that there is an increase in pedestrian crossing speed with increase in vehicle speed as well as heavy vehicle type.Pedestrian behavioural characteristics also have a significant influence on crossing speed.The study findings would provide useful information to designers and policy makers for design of pedestrian crossing facility under mixed traffic conditions.

Using multi-agent simulation to predict natural crossing points for pedestrians and choose locations for mid-block crosswalks

When arranging the pedestrian infrastructure,one of the most important components that make a tangible contribution to the safety of pedestrians is to organize the safe road crossing.In cities,pedestrians often cross a road in the wrong place due to established routes or inadequate location of crosswalks.Accidents with the participation of pedestrians who crossed the road neglecting the traffic rules,make up a significant part of the total amount of road accidents.In this paper,we propose a method that allows us,on the basis of the results of a computer simulation of pedestrian traffic,to obtain predicted routes for road crossing and to indicate optimal locations for crosswalks that take into account established pedestrian routes and increase their safety.The work describes an extension for the existing AntRoadPlanner simulation algorithm,which searches for and clusters points where pedestrians cross the roadway and suggests locations for new crosswalks.This method was tested on the basis of a comparative simulation of several territories before and after its application,as well as on the basis of a field study of the territories.The developed algorithm can also be used to search for other potentially dangerous places for pedestrians on plans of districts,for example,crossings in places with limited visibility.

基于Metadata crosswalks的青藏铁路元数据系统设计

人们对数据的需求随着所要研究问题复杂程度的升高而变得复杂多样。青藏铁路地理信息系统数据库管理着不同来源、异质异构的海量数据,元数据在这样的大型系统中扮演着非常重要的角色。元数据分为两类,一类是地理空间元数据,用来描述青藏铁路沿线基础地理背景数据、地形数据、铁路工程数据、与空间相关的冻土和冻土工程地质数据,及数据库运行过程中产生的不同版本的空间数据等;一类是非地理空间元数据,包括属性数据和事务性数据,用来描述钻孔资料、项目研究论文、野外观测资料等。两类数据采用不同的元数据标准,需要引入Metadatacrosswalks技术以解决不同标准元数据间的集成访问,从而为数据用户提供统一高效的元数据检索服务。XML技术是实现这种机制的最佳选择。探讨了Metadatacrosswalks在青藏铁路地理信息元数据库系统中的适用性并对其进行了初步的设计。

Numerical Simulation of Motor Vehicles’ Courtesy Behavior on Crosswalk Based on Car-Following Model

In observing driver courtesy towards pedestrians at unsignalized crosswalks, a behavioral model was adopted in a simulation based on the GM Car-Following Model. The SIMI Motion Software was used to extract the vehicle operation data from Wenyi South Road and Hanyuan Road in Xi'an City. The parameters of the GM Car-Following Model were calibrated by genetic algorithm. The road simulation environment based on the Car-Following Model was constructed by MATLAB. In the case of no stopping, uniform deceleration avoidance with advance notice, emergency brake avoidance without advance notice, changes such as the displacement of the Car-Following queue, headway, speed, acceleration, and deceleration were analyzed by numerical simulation. The results show that when there is advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.09 m, 7.38 m, 7.65 m, 7.91 m, and the average rates of change of the headway during deceleration are 0.78 m/s, 0.74 m/s, 0.71 m/s, 0.68 m/s respectively;in the absence of advance notice before the crosswalk, the minimum headway distances of Car1-Car2, Car2-Car3, Car3-Car4 and Car4-Car5 are 7.28 m, 7.75 m, 8.19 m, 8.59 m, and the average rates of change of the headway during deceleration are 1.57 m/s, 1.25 m/s, 1.04 m/s, 0.96 m/s, respectively. Therefore, in order to effectively prevent the occurrence of vehicle rear-end events, it's necessary to set traffic signs and markings on the preceding section of the intersection or road exhibiting behavioral comity.

Optimization of Crosswalk Width Based on Bi-Directional Pedestrian Crossing Time at Signalized Intersections

The effects of the interactions between bi-directional pedestrians on the crossing time and the crosswalk width are studied. Firstly,the crossing process of bi-directional pedestrians is analyzed.The total crosswalk time is divided into a discharge time and a crossing time. The interactions between bi-directional pedestrians are quantified with the drag force theory. Then,a model is developed to study the crossing time based on the kinetic energy theory and momentum theory. Subsequently,the related parameters of the proposed model are calibrated with observed information. The relationships among crosswalk width,signal time,pedestrian volume and level of service are simulated with the proposed model. The results are verified and compared with other models. The proposed model has an absolute value of relative error of 9. 38%,which is smaller than that of the Alhajyaseen model（ 15. 26%） and Highway Capacity Manual（ HCM） model（ 12. 42%）. Finally,suggested crosswalk widths at different conditions are successfully estimated with the proposed crossing time model.

Analyzing Pedestrian Fatality Risk in Accidents at Mid-Blocks

Objective: Pedestrian safety is considered as one of the greatest concerns, especially for developing countries. In the year of 2015, about 48% pedestrian accidents with 56% fatalities occurred at mid-blocks in Beijing. Since the high frequency and fatality risk, this study focused on pedestrian accidents taking place at mid-blocks and aimed at identifying significant factors. Methods: Based on total 10,948 crash records, a binary logit model was established to explore the impact of various factors on the probability of pedestrian’s death. Furthermore, first-degree interaction effects were introduced into the basic model. The Hosmer-Lemeshow goodness-of-fit test was used to assess the model performance. Odds ratio was calculated for categorical variables to compare significant accident conditions with the conference level. Variables within consideration in this study included weather, area type, road type, speed limit, pedestrian location, lighting condition, vehicle type, pedestrian gender and pedestrian age. Results: The calibration results of the model show that the increased fatality chances of an accident at mid-blocks are associated with normal weather, rural area, two-way divided road, crossing elsewhere in carriageway, darkness (especially for no street lighting), light vehicle, large vehicle and male pedestrian. With road speed limit increasing by 10 km/h, the probability of death accordingly increases by 46%. Older victims have higher chances of being killed in a crash. Moreover, three interaction effects are found significant: rural area and two-way divided, rural area and crossing elsewhere as well as speed limit and pedestrian age. Conclusions: This study has analyzed police accident data and identified factors significant to the death probability of pedestrians in accidents occurred at mid-blocks. Recommendations and improving measures were proposed correspondingly. Behaviors of different road users at mid-blocks should be taken into account in the future research.

Design Criteria for Crosswalk Width and Position at Signalized Intersections

Existing optimization methodologies for intersection operations assumes a fixed geometric design, however the geometry and operational system should be simultaneously optimized to produce the best performance. Signalized crosswalks are complex and critical pedestrian facilities. Their geometry and configuration directly affect the safety, cycle length and resulting delays for all users. As crosswalks become wider or they are placed further upstream, the cycle length will increase due to the all-red time requirement, which deteriorates the overall mobility levels of signalized intersections. In contrast, when crosswalk width decreases, the required minimum pedestrian crossing time increases due to the bi-directional pedestrian flow effects, which leads to longer cycle length. Furthermore, existing manuals and guidelines do not offer any specification for the required crosswalk width under various pedestrian demand conditions. This study aims to propose new criteria for designing crosswalk width at signalized intersections, which can optimize the performance from the viewpoint of vehicular traffic and pedestrians. The proposed methodology considers pedestrian demand and its characteristics （such as bi-directional flow effects）, vehicle demand and the geometric characteristics of the intersection The concept of optimized crosswalk width is proposed and demonstrated through a case study. Moreover, a comprehensive discussion regarding the merits and drawbacks of existing strategies on positioning crosswalks is presented. It was found that at signalized intersections, which are characterized by low pedestrian and high vehicle demands, crosswalk width of 2 meters is appropriate to minimize cycle length and resulting delays for all users including pedestrians.

无信号控制路段手机对行人过街行为和安全的影响

行人过街时使用手机会对其过街行为和交通安全产生一定的影响.本文以武汉市6个无信号路段交通调查数据为基础,对行人使用手机时的行为和安全性进行统计分析,并建立了基于Order Probit回归分析的人车冲突量化模型.结果表明:11.76%的行人在过街时会使用手机,其中看手机屏幕、打电话和听音乐分别占6.65%、2.83%和2.28%;使用手机对行人过街行为有明显影响,包括行人过街时间增加、过街眺望次数减小等;与不使用手机的行人相比,行人使用手机会有更大的几率与机动车产生冲突,其中,打电话对是否产生轻微冲突的影响最大,看手机屏幕对是否产生严重冲突的影响最大.

行人过街人车冲突等级评价及影响分析

无信号控制路段人车冲突等级的划分对于采取交通安全策略有重要意义,本文采用交通调查和数据分析的方法探索人车冲突严重程度的影响因素.通过视频采集确定了综合人、车、路3方面特性的14个解释变量,通过变量间相关性分析对解释变量进行筛选,再建立基于Odered Probit回归分析的人车冲突量化模型确定了影响显著的因素.

信号交叉口人行横道处的行人可接受间隙研究

在我国城市交叉口,大量行人与机动车的冲突导致了交叉口运行效率的下降,解决冲突问题是改善交叉口运行的一个重要方面。本文从信号交叉口处行人和机动车的冲突类型入手,利用Logit模型来描述行人选择间隙的行为。利用Track系统采集数据,标定车头时距、行人等待时间以及行人数量对行人选择间隙行为的影响系数。最后,通过对模型的检验和验证,证明该模型具有较好拟合度和预测精度。

协调交叉口间人行横道信号优化方法

引入行人过街等待容忍极限时间作为信号配时优化的约束条件之一,提出了线控路段上交叉口之间人行横道信号参数的信号协调控制优化方法.该方法先以两相邻交叉口共红时间作为行人过街绿灯时间,当共红时间不足时,利用路段机动车车队的离散性和流率关系建立延误函数,以机动车在人行横道处造成的总延误最小为目标求解配时优化参数.结果表明,该方法保证了行人过街的安全性,降低了行人延误.

元数据的互操作研究

在分布式信息环境中 ,元数据是描述、管理和组织信息资源的重要手段。为了能够有效地检索、描述、组织和利用不同的元数据格式描述的资源 ,就存在元数据的互操作问题。元数据的互操作可以通过元数据复用、元数据转换、元数据开放搜寻等方法实现。在讨论了元数据转换中 XML 语言、资源描述框架 RDF等问题的基础上 ,进一步研究了实现元数据转换的基本形式、匹配差异。

公交专用道路段停靠站与人行横道协调设计

综合考虑行人的安全、便捷和公交车辆的效率因素,详尽分析了停靠站位置、人行横道位置及停靠站与人行横道间距等3个关键参数的影响因素,并在此基础上建立了公交专用道条件下路段停靠站与人行横道协调设计模型,系统地提出了适用于包括路中式和路侧式专用道、有信号控制和无信号控制条件下的协调设计方法.最后,通过实例分析对该协调设计方法进行了完整的应用.

行人过街条件下道路路段机动车延误分析

通过对行人过街的三种情况即自由过街、无控制人行横道过街和信号控制人行横道过街进行研究,分析了不同过街条件下行人与机动车的运行特征.设定行人与机动车到达间距服从负指数分布,给出了不同条件下的机动车延误计算方法.研究结果表明,对行人过街选择合适的过街方式可以有效减少机动车的延误,特别是在行人与机动车交通量比较大时,设置人行横道(包括信号控制与无信号控制)可以大幅度减少机动车的延误.

信号灯对路段行人过街的影响研究

路段过街行人与直行机动车之间的冲突不仅增加了机动车的延误,也增加了机动车-行人事故发生的风险,而安全设施的设置对行人过街特性和机动车的驾驶特性有重要的影响,对此进行研究可为道路的安全审计和安全改造提供参考。

无信号控制路段人行横道行人过街时间研究

分析了城市道路无信号控制路段人行横道处行人和机动车的运行特性,针对行人利用可穿越间隙过街的特性得出行人的平均过街延误和过街时间.运用vissim软件仿真得出路段人行横道处不同的机动车量情况下行人的过街时间和机动车通过人行横道的时间,从而得到无信号控制路段人行横道改为信号控制的依据.仿真结果表明:在双向4车道的次干路中,当机动车流量超过2 400辆/h时,将人行横道改为信号控制时更适合行人过街.

考虑行人随机行为波动的改进社会力模型

为在仿真模型中更全面地反映行人特性,并研究随机行为对双向行人过街的影响,本文基于社会力模型建立了考虑行人随机行为的仿真模型.分析了随机行为对行人过街的影响,从速度和受力两个方面对行人随机行为进行建模,建立两个不同的行人随机行为模型.通过数值模拟,在双向行人比例1:1的条件下,得到了考虑随机行为条件下行人的仿真轨迹和行人平均过街时间与行人总数的关系;此外在不同行人随机行为各向异性参数λαε条件下,对比分析了仿真过街时间与经验模型过街时间.结果表明,行人随机行为导致过街时间增加,考虑随机行为后,改进模型二能够得到与实际相似的过街轨迹,当0.5<λαε<1时,改进模型二的行人仿真过街时间与利用经验模型得到的过街时间最为接近.

路段人行横道信号优化设计

城市路段信号控制的人行横道信号设置的合理与否,直接影响到过街行人的安全性和路段机动车延误的大小.本文从行人过街特性出发,通过对路段人行横道处行人与机动车调查数据的分析,提出了行人过街相位时长的设置与行人闯红灯行为的发生之间的关系,建立了以信号控制人行横道路段机动车平均延误最小为目标,以行人绿灯时长为变量的优化模型,并提出了模型求解的优化算法.最后通过算例,应用模型对信号设置进行了优化设计.结果表明,信号经过优化配置后,不仅减少了机动车的延误,还延长了行人过街相位时长,提高了信号周期内行人过街的通行能力,使信号控制人行横道系统达到最优化.

城市道路人行横道处驾驶人决策行为规律及损失

为给驾驶人在城市道路人行横道处安全通行提供决策依据,通过进行驾驶人决策与风险感知试验,对驾驶人的感知风险及决策行为进行分析.给出了驾驶人感知风险随机动车速度变化的规律及驾驶人决策行为的损失函数,基于概率论构建了驾驶人碰撞风险概率模型,并标定了在不同车速等级下的行车延误和碰撞风险损失.研究结果表明:当行车速度较低时,驾驶人采取匀速和加速为较优策略,而减速则会增加损失;当行车速度处于中等时,驾驶人采取加速、减速、匀速策略损失相差不大,但以匀速较优;当行车速度较高时,驾驶人对于自身的最优策略应该是保持匀速通过.

城市道路人行横道处夜间限速标志前置距离研究

为了保障过街行人的夜间出行安全,开展了城市道路人行横道处夜间限速标志前置距离研究.通过驾驶人夜间视认距离试验,分析了驾驶人夜间对过街行人视认距离随照度及行驶车速的变化规律,构建了驾驶人夜间视认距离与行驶车速、平均光照强度的关系模型.基于安全行驶判别条件,给出了城市道路人行横道处夜间限速标志前置距离的确定方法及对应不同路面类型、车速限制值和路灯平均照度的建议值.研究结果表明:城市道路人行横道处夜间限速标志前置距离宜根据车速限制值与路灯平均照度确定,车速限制值越低、路灯平均照度值越高,前置距离应越大;应用所提出的方法设置夜间限速标志,可以保证过街行人的夜间出行安全.