Using global positioning system for bus priority in London: traffic signals close to bus stops

London's bus network is one of the largest and most comprehensive urban transport systems in the world. The contribution of buses is recognised by implementing a series of initiatives including bus priority at traffic signals. London has a long history of the implementation of bus priority at traffic signals. It has kept pace with the development of new technologies by updating its bus priority system. Now, London is moving towards a bus management system based on global positioning system (GPS), which will also be used to provide bus priority at traffic signals. The authors describe theoretical work carried out by TRG on behalf of Transport for London Bus Priority Team to tackle the challenge posed by locational error associated with GPS where a traffic signal is close to a bus stop     

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.     

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.     

公交车辆停靠站位置对交通噪声的影响分析

以交通仿真为手段,结合日本ASJ道路交通噪声排放模型,研究不同状态下的公交停靠站位置对交通噪声的影响。结果表明当道路处于拥堵状态时,公交停靠站位置对交通噪声影响较小;当道路处于非拥堵状态下时,公交停靠站位置对交通噪声LA eq值影响约为1～2 dB、对TNI指标的影响高达15～17 dB。     

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.     

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.     

Incidence and characteristics of school bus crashes and injuries

Objective

Studies of school bus crashes have focused on the biomechanics of catastrophic collisions, with very few examining crash incidence.

Methods

Crashes in the state of Iowa were examined from January 2002 through December 2005. School bus crashes were identified through the Iowa Crash Data, a comprehensive database of all reported crashes in the State of Iowa. School bus mileage data were provided by the Iowa Department of Education. School bus crash, fatality, and injury rates were calculated and differences in crash and injury characteristics between school buses and other vehicles were examined.

Results

The school bus crash, fatality and non-fatal injury rates were 320.7, 0.4 and 13.6 per 100 million bus miles travelled, respectively. School bus crash fatality and injury rates were 3.5 and 5.4 times lower than overall all vehicle crash fatality and injury rates, respectively. Drivers of other vehicles were more likely to have caused the crash than the bus driver (P < 0.001).

Conclusions

School buses experience low crash rates, and the majority of crashes do not lead to injury. Buses are among the safest forms of road transportation, and efforts to educate drivers of other vehicles may help reduce crashes with buses.     

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.     

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.     

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.     

Pedestrian environment and behavior in Karachi, Pakistan.

Pedestrian road traffic accidents (RTAs) are responsible for a substantial number of injuries and deaths in Karachi. To better understand the situations facing pedestrians we selected ten of Karachi's highest risk locations for pedestrian RTAs and observed 250 pedestrians for each of three activities--crossing the street, walking on the street, and walking on the sidewalk. We also observed the extent and effect of street and sidewalk encroachments. A total of 35% of the pedestrians crossing the street caused traffic to swerve to avoid them. Pedestrians crossing one lane at a time were 2.9 times more likely to cause the traffic to swerve than pedestrians who crossed the whole street at once (53 vs. 18%, RR = 2.9, 95% CI = 1.9-4.3). Pedestrians crossing in a group were 1.8 times more likely to cause traffic to swerve compared to those crossing singly (49 vs. 28%, RR = 1.8, 95% CI = 1.3-2.5, P = 0.001). A total of 36% ran while crossing and were 1.8 times more likely to cause traffic to swerve than those who walked (48 vs. 27%, RR = 1.8, 95% CI = 1.3-2.5). An average of 77% of the sidewalk width was blocked by encroachments which forced pedestrians to step on the road resulting in vehicles swerving. An average 33% of the street width was blocked by illegally parked vehicles. Pedestrians in Karachi indulge in risky behaviors. Encroachments on streets and sidewalks compound the problem. Piloting efforts to modify pedestrian behavior and the environment they negotiate should be considered to reduce pedestrian deaths.     

基于路况适配下的城市专用校车造型设计

目的以满足我国儿童对专用校车安全性及舒适性的需求为目标,使其在符合我国城市路况环境的基础上,探索具有高度适配性的儿童专用校车设计方法和实践路径。方法通过对儿童行为及心理需求的分析,把握专用校车外观、内饰及车身附件的设计要素及实践方向,并分析路面状况、交通状况、道路规格等因素对于校车设计产生的影响,明确儿童专用校车的设计痛点和趋向目标。结果在系统分析了人、环境、车3种基本要素的基础上,依据设计方法及实践路径,开展儿童专用校车的外观及内饰设计,通过需求内涵的转译、美学要素的传达使设计实践结果达到了最终目标。结论儿童专用校车要综合考虑儿童心理、行为要素、环境系统等专用特种车特点,使其能够符合国情、国民特征,具备时代性和发展性。     

非港湾式公交站点影响路段长度研究

首先基于站位数分析了站点停靠公交车的最小车头时距,而后重点考虑公交进站的负指数分布和公交运行车速的BPR路阻模型,定量计算了主要道路各站位非港湾式公交站点不同线路数的影响路段长度,并获得公交站点最大可能影响路段长度随公交等价载客数和高峰小时公交平均发车数的变化关系,为比较真实反映非港湾式公交停靠影响提供了一种新思路。     

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.     

地铁列车运行引起的振动对精密仪器的影响研究

采用一种数值模型,并结合现场振动实测,对北京地铁4号线列车运行引起的振动对北京大学物理实验室内精密仪器的影响问题进行了研究,并对地铁4号线隧道内浮置板轨道的减振效果进行了探讨。该模型根据移动荷载作用下的动力响应解,把地铁列车运行引起的振动问题归结到计算频率-波数域内的传递函数和频域内移动轴荷载的问题上。传递函数采用三维周期性有限元-边界元耦合的数值模型来计算,移动轴荷载主要考虑为频域内轨道不平顺激励下的轮轨接触力。现场振动实测包括地铁列车与公交车单独引起的振动及两者的合振动测试。结果表明:浮置板轨道是一种有效的减振措施,在其工作频段内有显著的减振效果;在低频段,地铁列车单独引起的振动可能对精密仪器正常工作造成影响,公交车流单独引起的振动以及与地铁列车叠加的振动会对精密仪器的正常工作造成影响,仪器基座处应采取相应的隔振措施来减小这部分振动。     

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.     

Risk factors for severe injury in cyclists involved in traffic crashes in Victoria,Australia

This study examines the impact of cyclist, road and crash characteristics on the injury severity of cyclists involved in traffic crashes reported to the police in Victoria, Australia between 2004 and 2008. Logistic regression analysis was carried out to identify predictors of severe injury (serious injury and fatality) in cyclist crashes reported to the police. There were 6432 cyclist crashes reported to the police in Victoria between 2004 and 2008 with 2181 (33.9%) resulting in severe injury of the cyclist involved. The multivariate analysis found that factors that increase the risk of severe injury in cyclists involved in traffic crashes were age (50 years and older), not wearing a helmet, riding in the dark on unlit roads, riding on roads zoned 70 km/h or above, on curved sections of the road, in rural locations and being involved in head-on collisions as well as off path crashes, which include losing control of vehicle, and on path crashes which include striking the door of a parked vehicle. While this study did not test effectiveness of preventative measures, policy makers should consider implementation of programs that address these risk factors including helmet programs and environmental modifications such as speed reduction on roads that are frequented by cyclists.     

The real number of road traffic accident casualties in The Netherlands: a year-long survey

Between August 1986 and July 1987 more than 24,000 households, containing nearly 67,000 persons, were surveyed by telephone about traffic injuries during the past three months. Expressed on an annual basis, approximately 430,000 people, or about 1 in 34 of the Dutch population, had suffered some sort of injury in a road accident. The road traffic morbidity was, therefore, 2,942 per 100,000 inhabitants. Of these, about 135,000 had to be treated in hospital (20,000 as inpatients). More than 100,000 did not need treatment. Cyclists formed by far the largest category of road user, but mopedists had the highest injury rate per kilometer travelled. 210,000 of these casualties fell within the definition for recording by the police. The police recorded only 49,748 traffic casualties, or about 25%, during the same period. The police data were not representative; the completeness declined according to severity of the injuries: inpatients, about 70%; outpatients 26%; extramural about 11%. Cyclists (11%), children (9%), and single vehicle accidents (5%) were very much underrepresented. The largest category of road user is cyclists, not car occupants as indicated by the police data. A number of recommendations are made for supplementing the police data and the existing hospital inpatient data. These include extending the Home Accident Recording System of outpatients and the General Practitioner Panel to include road accident victims. Together a representative sample of 95% of all those receiving medical treatment would thus be obtained.     

Road traffic crashes on the Yaoundé-Douala road section, Cameroon

Objective

Developing countries account for more than 85% of all road traffic deaths in the world. Our aims were to estimate road morbidity and mortality and to describe the main characteristics of road traffic crashes on a heavy traffic road section in Cameroon.

Methods

We conducted a study of police reports of the 2004-2007 period retrieved from the 13 police stations in charge of the 243 km Yaoundé-Douala road section in Cameroon.

Results

The estimated overall number of people killed per 100 million kilometres driven was 73, more than 35 times higher than on similar roads in the US or Europe. The most severe crashes were those involving vulnerable road users (97 deaths) and vehicles travelling in opposite directions (136 deaths). The main causes of fatal crashes were mechanical failures (28%), two-thirds being tyre problems, hazardous overtaking (23%), and excessive speed (20%).

Conclusions

The burden of road traffic injuries on heavy traffic roads in Cameroon calls for urgent interventions. Traffic calming measures and control of vehicle condition appear to be the most cost-effective interventions.     

Motorcycle crash characteristics in Nigeria: Implication for control

Despite being the second most common cause of road traffic injuries (RTIs) in Nigeria, no study had examined the peculiarities of motorcycle crash site characteristics in Nigeria.We examined and interviewed 363 motorcycle RTI patients in three tertiary hospitals in southwest Nigeria. All the motorcycles are small with capacities between 80 and 125 cm³. 68.9% of the patients sustained their injuries while working or going to work and 23.4% on their way to school. 176 (48.5%) of the crashes were with moving vehicles and in 83 (22.3%) cases, either the motorcycle or the other vehicle is moving against the traffic. 37.8% of all crashes occurred at junctions with no roundabout versus 5% at junctions with roundabout. Some risky practices of the patient included carrying more than 2 persons (15.02%), travelling without headlight at night (31.7%) and not wearing helmets (96.5%).This study showed that risky behavior among motorcycle riders, chaotic traffic and road design faults accounted for most of the motorcycle crashes. The implications for the prevention and control of motorcycle injuries were discussed.