The way ahead for London's bus priority at traffic signals

London has a long history of successful schemes for bus priority at traffic signals. Recently, transport for London (TfL) has procured a modern automatic vehicle location (AVL) system for bus fleet management, passenger information and bus priority. The new system is known as iBUS and is based on Global Positioning System (GPS) and supporting technologies for bus location. The system eliminates the need for on-street hardware for detecting buses and provides more flexibility and opportunity for using bus detectors. However, bus location based on this system is less accurate than location based on fixed infrastructure (e.g. beacons) and could result in reduced benefits from bus priority. This paper first summarises how bus priority at traffic signals works within iBUS, and then explores the effects of GPS locational errors on bus priority benefits. This is followed by a discussion of opportunities available in the context of iBUS to build an even more efficient and beneficial bus priority system by taking advantage of its cost-effective multiple detection capabilities. The paper is based on various studies carried out by the Transportation Research Group (TRG) at the University of Southampton for TfL.     

Factors affecting the probability of bus drivers being at-fault in bus-involved accidents

Previous research has provided little insight into factors that influence the probability of bus drivers being at-fault in bus-involved accidents. In this study, an analysis was conducted on accident data compiled by a bus company that include an assessment on whether the bus driver was deemed by the company to hold primary responsibility for accident occurrence. Using a mixed logit modelling approach, roadway/environmental, vehicle and driver related variables that were identified to be influential were road type, speed limit, traffic/lighting conditions, bus priority, bus age/length and driver's age/gender/experience/historic at-fault accident record. Results were indicative of possible confined road-space issues that bus drivers face along routes with roadside traffic friction and point to the provision of exclusive right of way for buses as a possible way to address this. Results also suggest benefits in assigning routes comprising mainly divided roads as well as newer and shorter buses to less experienced drivers.     

Risky behavior of bus commuters and bus drivers in Karachi, Pakistan.

Buses account for a disproportionate number of road traffic accident fatalities in Karachi, Pakistan and other developing countries. Potentially dangerous bus driving and commuting practices that increase risk of road accidents and the effect of traffic police on bus behavior are evaluated. A total of 250 episodes each of disembarking and embarking commuters, buses stopping and moving on the road at ten of Karachi's highest risk intersections for traffic injuries were observed. Of the disembarking passengers, 33% did not wait for the bus to stop; 54% stepped off in the center of the road and 84% did not look out for traffic. Among the embarking commuters, 38% got on moving buses; 73% climbed on buses filled to their outer foot boards and 83% waited for buses on the street. Males were more likely than females to jump off a moving bus (43% versus 1.6%, P < 0.001), get on a moving bus (49% versus 12%, P < 0.001), and run to catch a bus (45% versus 8%, P < 0.001). At the bus stops, 30% of the buses did not stop completely; 46% stopped away from the stop and 79% stopped in the center of the road. Where traffic police were present buses were more likely to race (9% versus 3%, P = 0.05) and to cut off other vehicles (13% versus 2%, P = 0.001) than where police were absent. Risky behavior is common among both Karachi bus drivers and bus commuters. The traditional efforts to regulate bus traffic through traffic police is ineffective.     

Bus accident analysis of routes with/without bus priority

This paper summarises findings on road safety performance and bus-involved accidents in Melbourne along roads where bus priority measures had been applied. Results from an empirical analysis of the accident types revealed significant reduction in the proportion of accidents involving buses hitting stationary objects and vehicles, which suggests the effect of bus priority in addressing manoeuvrability issues for buses. A mixed-effects negative binomial (MENB) regression and back-propagation neural network (BPNN) modelling of bus accidents considering wider influences on accident rates at a route section level also revealed significant safety benefits when bus priority is provided. Sensitivity analyses done on the BPNN model showed general agreement in the predicted accident frequency between both models. The slightly better performance recorded by the MENB model results suggests merits in adopting a mixed effects modelling approach for accident count prediction in practice given its capability to account for unobserved location and time-specific factors. A major implication of this research is that bus priority in Melbourne's context acts to improve road safety and should be a major consideration for road management agencies when implementing bus priority and road schemes.     

CAN总线综述及其应用实例

本文介绍了CAN总线的基本知识,对其技术指标进行了叙述,并介绍了一个基于CAN总线的应用．采用VB语言编程,利用CAN现场总线技术以及华控RSM智能模块搭建分布式监控系统的逻辑结构,采用CAN2．0通讯协议实现上位机与模块的数据通信。详细介绍了RSM04隔离型脉冲输入计数器模块与上位计算机的连接与通讯实现。在实验过程中模拟了信号发生源,其发出的信号经模块采集后送至上位机．执行计数值程序后,可以读取计数结果。     

A bi-objective optimization approach for exclusive bus lane selection and scheduling design

This study proposes a methodology to solve the integrated problems of selection and scheduling of the exclusive bus lane. The selection problem intends to determine which roads (links) should have a lane reserved for buses while the scheduling problem intends to find the time period of the application. It is formulated as a bi-objective optimization model that aims to minimize the total travel time of non-bus traffic and buses simultaneously. The proposed model formulation is solved by the hybrid non-dominated sorting genetic algorithm with Paramics. The results show that the proposed methodology is workable. Sets of Pareto solutions are obtained indicating that a trade-off between buses and non-bus traffic for the improvement of the bus transit system is necessary when the exclusive bus lane is applied. This allows the engineer to choose the best solutions that could balance the performance of both modes in a multimode transport system environment to achieve a sustainable transport system.     

Hybrid free-space optical bus system for board-to-board interconnections

A free-space optical bus system is described for board-to-board interconnections at the backplane level. The system uses active optoelectronic modules as the interface between the circuit boards and the electrical backplane. Substrate-mode holograms are used to implement signal broadcast operations between boards, and each board on the backplane shares common free-space channels for transmitting and receiving signals. System-design considerations are given, and the potential performance of the optical bus system is evaluated. An experimental demonstration is also presented for the signal broadcast operation through cascaded substrate-mode holograms at a data rate of 622 Mb/s.     

面向产业化的电动城市客车关键技术研究

电动汽车的产业化面临整车性能、成本和可靠性的问题,HFF6112GK50EV型电动客车作为国内第一款列入国家发展与改革委员会车辆产品公告的电动汽车,在关键技术的研究过程中充分考虑了这些问题。电动客车的关键技术包括动力系统、整车车身结构设计与分析、整车控制和能量管理系统等。对上述关键技术进行了研究,试验结果显示,在有效控制整车成本的基础上,该车动力性和经济性均超过合同规定的指标并达到国内先进水平,并且通过了5 000 km可靠性考核试验,目前正在接受公交工况的运行考核。     

Powered two-wheeler drivers’ crash risk associated with the use of bus lanes

Context

Authorizing powered two-wheeler drivers to drive in lanes reserved to buses is a measure that is sometimes mentioned to improve mobility conditions for these users. But what effect would this measure have on the safety of these users and on the safety of the other users with whom they share the traffic space?

Objective

The objective of this study is to contribute elements to help answer this question. More precisely, the objective is to estimate the risk of having an accident per kilometer driven by powered two-wheeler drivers who drive in bus lanes and to compare this risk with that of powered two-wheeler drivers who drive in general traffic lanes.

Method

Using the bodily injury accidents recorded by the police over two years on 13 roads in the city of Marseille and a campaign of periodical observations of powered two-wheeler traffic, we estimated the risk per kilometer driven by powered two-wheeler drivers who drive in bus lanes and compared it with that of drivers who do not drive in them.

Results

The results show that the risk for powered two-wheeler drivers who drive in bus lanes of being involved in a bodily injury accident is significantly higher than the risk run by drivers who drive in general traffic lanes. For the 13 roads studied, it is on average 3.25 times higher (95% CI: 2.03; 5.21).

Conclusion

In the current situation, powered two-wheeler drivers who drive in bus lanes are less safe than those who drive in general traffic lanes. The analysis of police reports suggests that part of this increased risk comes from collisions between automobile drivers turning right and powered two-wheelers driving in the bus lane who continue straight ahead.     

Road safety issues for bus transport management

Because of the low percentage of crashes involving buses and the assumption that public transport improves road safety by reducing vehicular traffic, public interest in bus safety is not as great as that in the safety of other types of vehicles. It is possible that less attention is paid to the significance of crashes involving buses because the safety level of bus systems is considered to be adequate.     

Effect of bus size and operation to crash occurrences

This paper evaluates roadway and operational factors considered to influence crashes involving buses. Factors evaluated included those related to bus sizes and operation services. Negative binomial (NB) and multinomial logit (MNL) models were used in linearizing and quantifying these factors with respect to crash frequency and injury severities, respectively. The results showed that position of the bus travel lane, presence or absence of on-street shoulder parking, posted speed limit, lane width, median width, number of lanes per direction and number of vehicles per lane has a higher influence on bus crashes compared to other roadway and traffic factors. Wider lanes and medians were found to reduce probability of bus crashes while more lanes and higher volume per lane were found to increase the likelihood of occurrences of bus-related crashes. Roadways with higher posted speed limits excluding freeways were found to have high probability of crashes compared to low speed limit roadways. Buses traveling on the inner lanes and making left turns were found to have higher probability of crashes compared to those traveling on the right most lanes. The same factors were found to influence injury severity though with varying magnitudes compared to crash frequency.     

大客车侧翻碰撞护栏事故仿真分析及改进

建立大客车与护栏有限元模型,仿真大客车侧翻碰撞护栏型交通事故,并与我国GB/T 17578-1998及欧盟ECE R66规定对比。仿真结果表明此类侧翻事故的损害程度远超规定;进而改进大客车侧面立柱材料及厚度,仿真验证表明,此方法可减小事故损失。可供设计人员参考。     

基于CAN总线的条码扫描器管理系统

传统的数据采集系统一般采用485作为组网方式,485本身存在很大的局限性,总线效率低、系统的实时性差、通讯的可靠性低、后期维护成本高、网络工程调试复杂、传输距离不理想、单总线可挂节点少、应用不灵活等。基于CAN总线的数据采集系统解决了485网络的固有问题,CAN总线是国际上应用最广泛的现场总线之一。该系统采用Philips的基于ARM的带有CAN控制器的LPC2364作为主控制器,实现数据实时的采集。通过功能强大的数据管理软件,实现库存、生产、财务等多个生产过程信息化,方便信息管理、维护及查询。     

Crashworthiness assessment of a paratransit bus

Most of the bus safety standards in the USA are not applicable to cutaway buses for which a production process is split into two stages. First, the chassis and cab section are assembled by automobile manufactures. Then the vehicle is shipped to another company, where bus body and additional equipment are installed. Lack of strict structural standards for transit bus body builders stimulates the need for crashworthiness and safety evaluation for this category of vehicles.This study focused on a selected transit bus, the Ford Eldorado Aerotech 240. Due to the lack of design data the reverse engineering process was used to acquire the geometric data of the bus. The finite element (FE) model was developed based on the geometry obtained by disassembling and digitizing all major parts of the actual bus.The FE model consists of 73,600 finite elements, has 174 defined properties (groups of elements with the same features) and 23 material models. LS-DYNA non-linear, explicit, 3-D, dynamic FE computer code was used to simulate behavior of the FE model under different impact scenarios, such as front impact and side impact of two buses at various velocities.     

Parallel algorithms for generating combinatorial objects on linear processor arrays with reconfigurable bus systems

A bus system whose configuration can be dynamically changed is called reconfigurable bus system. In this paper, parallel algorithms for generating combinations, subsets, and binary trees on linear processor array with reconfigurable bus systems (PARBS) are presented. Preliminary version of this paper has been presented at the 6th National Seminar on Theoretical Computer Science, held at Bhanasthali Vidyapith, Aug. 8–12, 1996     

A robust bus evacuation model with delayed scenario information

Due to natural or man-made disasters, the evacuation of a whole region or city may become necessary. Apart from private traffic, the emergency services also need to consider transit-dependent evacuees which have to be transported from collection points to secure shelters outside the endangered region with the help of a bus fleet. We consider a simplified version of the arising bus evacuation problem (BEP), which is a vehicle scheduling problem that aims at minimizing the network clearance time, i.e., the time needed until the last person is brought to safety. In this paper, we consider an adjustable robust formulation without recourse for the BEP, the robust bus evacuation problem (RBEP), in which the exact numbers of evacuees are not known in advance. Instead, a set of likely scenarios is known. After some reckoning time, this uncertainty is eliminated and planners are given exact figures. The problem is to decide for each bus, if it is better to send it right away—using uncertain information on the evacuees—or to wait until the the scenario becomes known. We present a mixed-integer linear programming formulation for the RBEP and discuss solution approaches; in particular, we present a tabu search framework for finding heuristic solutions of acceptable quality within short computation time. In computational experiments using both randomly generated instances and the real-world scenario of evacuating the city of Kaiserslautern, Germany, we compare our solution approaches.     

Air flow through a non-airconditioned bus with open windows

Open window buses without air-conditioning are a major mode of urban and inter-city transport in most countries. High occupancy combined with hot and humid conditions makes travel in these buses quite uncomfortable. In this study air flow through a bus has been studied that could be the basis for low cost and eco-friendly methods of increasing passenger comfort and possibly reduce drag. The aerodynamics of such a road vehicle has not been studied as previous investigations have been confined to vehicles with closed windows that present a smooth exterior to air flow. Using a 1:25 scaled Perspex model of an urban bus in Delhi, flow visualization was performed in a water channel. The Reynolds numbers were one-tenth of a real bus moving at 10 m/s. Smoke and tuft visualizations were also performed on an urban bus at 40 km/h. Numerical simulations were performed at the actual Reynolds number. Even though there were Reynolds number differences, the broad features were similar. Air enters the bus from the rear windows, moves to the front (relative to the bus) and exits from the front windows. Inside air velocity relative to the bus is about one-tenth of the free-stream velocity. The flow is highly three-dimensional and unsteady.     

纯电动客车振动试验分析及动力总成隔振优化

汽车电动化使动力总成的振动噪声特性发生很大变化,带来了新的NVH问题,作为短途客运主要运输工具的纯电动客车尤为明显。针对某纯电动客车在行驶中存在振动较大的问题,结合实车试验与理论仿真,研究其振动传递特性及隔振优化。首先,基于LMS Test.lab振动噪声测试平台,采集了车内地板与底盘关键点的振动信号进行振动试验分析,根据车内地板振动响应特性对18条振动传递路径进行振动贡献量分析,求解出各个传递路径对车内目标点振动的贡献量,确定振动的主要贡献路径。其次,根据传递路径分析结果,针对主要贡献路径上的减振关键环节(动力总成悬置)进行隔振性能分析,结果显示电机动力总成悬置系统较差的隔振性能是引起车内振动过大的主要原因。为此,进一步建立了六自由度动力总成优化模型,采用多岛遗传优化方法对悬置系统参数进行优化匹配设计。结果表明,悬置系统的隔振性能获得了显著提升,车内振动过大问题得到有效解决。     

A BP neural network based information fusion method for urban traffic speed estimation

Obtaining comprehensive and accurate information is very important in intelligent traffic system (ITS). In ITS, the GPS floating car system is an very important approach for traffic data acquisition. However, in this system, the GPS blind areas caused by tall buildings and tunnels could affect the acquisition of traffic information and depress the system performance. Aiming at this problem, we developed a novel method employing a back propagation (BP) neural network to estimate the traffic speed in the GPS blind areas. When the speed of one road section is lost, we can use the speed of its related road sections to estimate its speed. The complete historical data of these road sections are used to train the neural network, using Levenberg-Marquardt learning algorithm. Then, the current speed of the related roads is used by the trained neural network to get the speed of the road section without GPS signal. We compare the speed of the road section estimated by our method with the real speed of this road section, and the experimental results show that the speed of this road section estimated by our method is better.     

Crash risk and aberrant driving behaviors among bus drivers: The role of personality and attitudes towards traffic safety

Several studies have shown that personality traits and attitudes toward traffic safety predict aberrant driving behaviors and crash involvement. However, this process has not been adequately investigated in professional drivers, such as bus drivers. The present study used a personality–attitudes model to assess whether personality traits predicted aberrant self-reported driving behaviors (driving violations, lapses, and errors) both directly and indirectly, through the effects of attitudes towards traffic safety in a large sample of bus drivers. Additionally, the relationship between aberrant self-reported driving behaviors and crash risk was also assessed.