Performance Evaluation of Hybrid-Drive Buses and Potential Fuel Savings in Brazilian Urban Transit

Transporting more than 55 million passengers per day, buses are the main transit mode in Brazil. Most of these vehicles use diesel oil and this situation causes dependence on oil, extensive greenhouse gas emissions and increasing air pollution in urban areas. In order to improve this situation the options for Brazilian cities include the use of alternative fuels and new propulsion technologies, such as hybrid vehicles. This article proposes a procedure for evaluating the performance of a recently developed Brazilian hybrid-drive technology. A simple procedure is presented to compare hybrid-drive buses with conventional diesel buses in urban operation focusing on fuel economy and the potential for reducing diesel oil consumption through the use of hybrid-drive buses. Field tests carried out by the authors indicate that fuel consumption improvement through the use of hybrid-drive buses would certainly exceed 20%, resulting in lower fuel costs and reduced carbon dioxide (CO₂) emissions.     

Understanding the impacts of a combination of service improvement strategies on bus running time and passenger’s perception

Transit agencies implement many strategies in order to provide an attractive transportation service. This article aims to evaluate the impacts of implementing a combination of strategies, designed to improve the bus transit service, on running time and passenger satisfaction. These strategies include using smart card fare collection, introducing limited-stop bus service, implementing reserved bus lanes, using articulated buses, and implementing transit signal priority (TSP). This study uses stop-level data collected from the Société de transport de Montréal (STM)’s automatic vehicle location (AVL) and automatic passenger count (APC) systems, in Montréal, Canada. The combination of these strategies has lead to a 10.5% decline in running time along the limited stop service compared to the regular service. The regular route running time has increased by 1% on average compared to the initial time period. The study also shows that riders are generally satisfied with the service improvements. They tend to overestimate the savings associated with the implementation of this combination of strategies by 3.5-6.0 min and by 2.5-4.1 min for both the regular route and the limited stop service, respectively. This study helps transit planners and policy makers to better understand the effects of implementing a combination of strategies to improve running time and passenger’s perception of these changes in service.     

环保客车发展面临的机遇与挑战

着重分析了目前汽车排放污染的严重性，并从能源结构调整和环保两大意义上阐述了发展环保型客车的必要性。目前的形势给环保型客车的发展带来很好的机遇，同时，由于我国环保客车技术尚未成熟，很多技术上的问题亟待解决。     

轨道交通接运公交专线现状特性分析

文章通过对广州市地铁接运公交专线现状的调研，分析了我国大城市轨道交通接运公交的现状特性及影响其运营性能的各种因素，探讨了提高运营性能的方法，为类似城市轨道交通接运公交专线的规划提供参考。     

城市公交站点自行车对公交车的干扰行为研究

以北京市两个不同类型的典型公交站点为例,研究了公交站点处自行车对公交车的干扰行为,并建立了不同因素影响下自行车对公交车的干扰行为模型,进而对其进行验证.最后,提出了几点减少公交站点处自行车对公交车干扰的建议.     

低地板公交车结构轻量化研究

本论文主要通过对低地板公交车结构轻量化设计背景的阐述,低地板公交车轻量化技术作用和发展现状的研究,进一步讨论了低地板公交车轻量化技术所存在的不足,最后提供了实现低地板公交车结构轻量化的途径和在行业中的应用,从而为低地板公交车行业轻量化设计提供有效的帮助。     

Potential of low viscosity oils to reduce CO2 emissions and fuel consumption of urban buses fleets

This paper shows the results of a comparative fleet test the main objective of which was to measure the influence of Low Viscosity Oils (LVO) over the fuel consumption and CO₂ emissions of urban buses. To perform this test, 39 urban buses, classified into candidate and reference groups depending on the engine oil viscosity, covered a 60,000 km mileage corresponding to two rounds of standard Oil Drain Interval (ODI). In the same way, for 9 buses of the 39 buses, the effect of differential LVO over fuel consumption and their interaction with engine LVO was assessed during the second ODI.Test results confirm that the use of LVO could reduce fuel consumption, hence CO₂ emissions. However, special attention should be taken prior to its implementation in a fleet, particularly if the vehicles are powered by engines with high mechanical and thermal stresses during vehicle operation because this could lead to friction loss increase, loss of the potential fuel consumption reduction of LVO and, in the worst scenario, higher rates of engine wear.     

公交车中途停靠站长度预测方法研究

根据车辆泊松到达分布,运用概率分布与数理统计方法,分析公交线路条数、发车频率以及到达公交车中途停靠站时间分布之间的关系,建立同时到达车辆数概率模型,据此确定某一概率水平下公交车中途停靠站设计停车位数量及车站长度。以北京菜市口公交车中途停靠站为例,运用模型进行演算,并与实际观测值进行对比验证,提出将公交车中途停靠站向交叉口靠近从而方便换乘的改善方案。     

‘Regulated deregulation’ of local bus services—An appraisal of international developments

The deregulation of the British bus sector (outside London) in 1986 was the start of a debate on the merits of ‘deregulation’ and ‘competitive tendering’. The period that followed was rich in lessons. New Zealand was at the time the only other country engaging in a reform based upon market initiative (implemented in 1991). Other countries chose for a less extreme and more consensual way to introduce competitive incentives, choosing the fundamentally different competitive tendering (CT) path. As a result, the so-called ‘Scandinavian model’ developed, based upon the London example of route tendering. Later the Netherlands adopted a network tendering approach, resembling the French practice of network tendering though with more operator freedom.