Low-floor Bus Research Articles

A study on the crashworthiness and rollover characteristics of low-floor bus made of sandwich composites

This paper describes the results of the numerical evaluation on crashworthiness and rollover characteristics of a lowfloor bus vehicle made of sandwich composites. The sandwich composite used for the vehicle structures was composed of aluminum honeycomb core and WR580/NF4000 glass-fabric/epoxy laminate facesheets. Material tests were conducted to determine the input parameters of the composite laminate facesheet model and the effective equivalent damage model for the orthotropic honeycomb core material. Crashworthiness and rollover analysis of the low-floor bus was conducted using the explicit finite element method (FEM) analysis code LS-DYNA3D with the lapse of time. The crash condition of the low-floor bus was a frontal accident with a speed of 60 km/h. Rollover analysis was done according to the safety rules of the European standards (ECE-R66). The angular and translation velocity and its angle with the ground just before impact for rollover were calculated using the dynamic analysis program. The results showed that the survival spaces for the driver and passengers were secured against frontal crashworthiness and rollover of the low-floor bus. In addition, the modified Chang-Chang failure criterion is recommended to predict the failure modes of the composite structures for crashworthiness and rollover analysis.

Flexible transport services: A new market opportunity for public transport

The term Demand-Responsive Transport (DRT) has been increasingly applied in the last 10 years to a niche market that replaces or feeds (usually via small low floor buses or taxis) conventional transport where demand is low and often spread over a large area. More recently, the concept of DRT as a niche market has been broadened to include a wider range of flexible, demand-responsive transport services and is increasingly referred to as Flexible Transport Services (FTSs). The contention of this paper is that well-implemented FTS has the potential to revitalise bus-based public transport services which are traditionally based on fixed networks with variable geographical coverage and levels of service.

Research on Anti-slip Flooring in Response to Standardization of Low-floor Buses: The Proposed Synthetic Material Based on Functional Evaluation in Conditions of Rain and Snow

Research on Anti-slip Flooring in Response to Standardization of Low-floor Buses: The Proposed Synthetic Material Based on Functional Evaluation in Conditions of Rain and Snow

Bus Dynamics for Mobility-Aid Securement Design

Mobility-aid securement on large urban transit buses has been designed without an adequate knowledge of either the accelerations that are likely to occur in normal operations or the maximum accelerations that are possible short of an impact accident. These normal operation accelerations are important because they are the source of motion and corresponding sense of insecurity on the part of the passenger when riding in a mobility-aid on a bus. This paper describes the equipment and procedures used to measure the distribution of accelerations to be expected on large buses in normal transit service and the maximum accelerations possible during extreme maneuvering for six different sizes and types of transit buses. Included in the tests were low-floor buses of different lengths, a high-floor bus, a 40-ft (12.2-m) low-floor double-decker bus, and a 60-ft (18.3-m) low-floor articulated bus. During in-service tests, the accelerations were generally a function of the driver. In maneuvering tests, the mechanics of the bus design were the controlling factors. The results show that, in general, normal driving accelerations were typically less than 0.2 g in all directions and very rarely greater than 0.4 g. In the event of an emergency-driving situation, forward and turning accelerations may reach 0.4 g and stopping may result in 0.8 g.

An experimental study of low-velocity impact responses of sandwich panels for Korean low floor bus

This paper describes the results of an experimental investigation on the low-velocity impact response of four different types of sandwich structures considered as the structural materials of the Korean low floor bus. The test panels were subjected to low-velocity impact loading using an instrumented testing machine at six energy levels. Impact parameters like maximum contact force, contact time, deflection at peak load and absorbed energy were evaluated and compared for different types of sandwich panels. The extent of the damage and depth of the permanent indentation was measured quantitatively using 3-dimensional scanner. Failure modes were studied by sectioning the specimens and observed under optical microscope. The impact test results show that sandwich panels with woven glass fabric/epoxy facesheet could not observe permanent visible impact damage and has a good impact damage resistance in comparison with sandwich panel with metal aluminum facesheet.

초저상 버스 차체 적용을 위한 샌드위치 패널들의 저속충격 특성 연구

In this paper, a study on low-velocity impact response of four different sandwich panels for the hybrid bodyshell and floor structure application of the Korean low floor bus vehicle was done. Square samples of 100mm sides were subjected low-velocity impact loading using an instrumented testing machine at six energy levels. Impact parameters like maximum force, time to maximum force, deflection at maximum force and absorbed energy were evaluated and compared for four different types of sandwich panels. The impact damage size and depth of the permanent indentation were measured by 3-Dimensional Scanner. Failure modes were studied by sectioning the specimens and observed under optical microscope. The impact test results show that sandwich panel with composite laminate facesheet could not observe damage mode of a permanent visible indentation after impact and has a good impact damage resistance in comparison with sandwich panel with metal aluminum facesheet.

Unregulated Emissions from Compressed Natural Gas (CNG) Transit Buses Configured with and without Oxidation Catalyst

The unregulated emissions from two in-use heavy-duty transit buses fueled by compressed natural gas (CNG) and equipped with oxidation catalyst (OxiCat) control were evaluated. We tested emissions from a transit bus powered by a 2001 Cummins Westport C Gas Plus 8.3-L engine (CWest), which meets the California Air Resources Board's (CARB) 2002 optional NOx standard (2.0 g/bhp-hr). In California, this engine is certified only with an OxiCat, so our study did not include emissions testing without it. We also tested a 2000 New Flyer 40-passenger low-floor bus powered by a Detroit Diesel series 50G engine (DDCs50G) that is currently certified in California without an OxiCat. The original equipment manufacturer (OEM) offers a "low-emission" package for this bus that includes an OxiCat for transit bus applications, thus, this configuration was also tested in this study. Previously, we reported that formaldehyde and other volatile organic emissions detected in the exhaust of the DDCs50G bus equipped with an OxiCat were significantly reduced relative to the same DDCs50G bus without OxiCat. In this paper, we examine othertoxic unregulated emissions of significance. The specific mutagenic activity of emission sample extracts was examined using the microsuspension assay. The total mutagenic activity of emissions (activity per mile) from the OxiCat-equipped DDC bus was generally lower than that from the DDC bus without the OxiCat. The CWest bus emission samples had mutagenic activity that was comparable to that of the OxiCat-equipped DDC bus. In general, polycyclic aromatic hydrocarbon (PAH) emissions were lower forthe OxiCat-equipped buses, with greater reductions observed for the volatile and semivolatile PAH emissions. Elemental carbon (EC) was detected in the exhaust from the all three bus configurations, and we found that the total carbon (TC) composition of particulate matter (PM) emissions was primarily organic carbon (OC). The amount of carbon emissions far exceeded the PM-associated inorganic element emissions, which were detected in all exhaust samples, at comparatively small emission rates. In summary, based on these results and those referenced from our group, the use of OxiCat for the new CWest engine and as a retrofit option for the DDCs50G engine generally results in the reduction of tailpipe toxic emissions. However, the conclusions of this study do not take into account OxiCat durability, deterioration, lubricant consumption, or vehicle maintenance, and these parameters merit further study.

Introducing and Sustaining Accessible Transport: Social and Physical Challenges

Improvements in transportation accessibility are being made in the Netherlands. The Ministry of Transport issued leaflets with suggestions to direct development, and Delft University of Technology was asked to illustrate these suggestions with practical examples. In the course of this effort, enough material was collected to present a comparative state of the art. Bus systems in seven areas were critiqued. The assessment showed that progress in certain aspects was more prominent than in others. Low-floor buses are being introduced nearly everywhere, but the adaptation of bus stops is lagging behind. Ideas about bus interiors are rather confused. One essential feature, the seat, is treated unsatisfactorily. The driving behavior of bus drivers often does not take vulnerable passengers into account. Accessibility actually decreases in some cases because of insufficient specifications in contracts. Further progress in accessibility seems to require more guidelines and information campaigns.

Transport policy for an ageing population

Mobility declines with increasing age, reflecting the onset of physical or mental infirmity, affordability of travel for those on retirement incomes, and the mal-design of the transport infrastructure and operational arrangements. With the prospect of a rapidly ageing population, it is important to address measures to promote mobility if the quality of life of older people is to be sustained. In the UK, pensioners on low incomes, who could be hindered in their travel by the cost of fares on public transport, benefit from the general availability of half price (or better) concessionary fares for local travel. A variety of measures are in place to counter the effects of age-associated disabilities that hinder mobility, including low floor buses, subsidised taxis and community transport schemes. The Disability Discrimination Act is ensuring that public services vehicles are accessible to older people with disabilities. The motor car is of increasing importance in later life, particularly for those with disabilities, and a variety of design and technological approaches are being brought to bear to maintain the mobility of older people. These various efforts undoubtedly enhance the mobility of older people. However, beyond that broad conclusion it is hard to make evidencebased judgements. There is therefore a pressing need to develop methods to evaluate developments in policy and practice.

Development of capacitor hybrid system for urban buses

The authors have developed a capacitor hybrid vehicle equipped with a newly developed capacitor system and a miller cycle CNG engine for low floor urban buses. The CNG engine drives a generator at over 40% thermal efficiency. The newly developed capacitor system, since it has high energy and power density, is able to regenerate almost all the braking energy of a 14-ton bus at over 90% charging efficiency. The internal resistance of the capacitor system is minimized by the capacitor itself and a new capacitor connection. Furthermore, the voltage dispersion of the capacitor cells is minimized by the capacitor charging control system. The fuel economy was improved by 166% compared with the CNG low-floor bus and the vehicle efficiency reached over 45% in the M15 mode test.

Theoretical understanding and methodological challenges in accessibility assessments, focusing the environmental component: an example from travel chains in urban public bus transport

In order to increase the theoretical understanding of the concept of accessibility, this paper reports the results from an exploration of methodological difficulties inherent in systematic accessibility assessments of single persons' travel chains in urban public bus transport. In addition, Special Transport Service (STS) travellers' perception of environmental demands in public transport are reported.This study was designed to explore the environmental component in accessibility problems systematically. Twenty persons entitled to STS were recruited in order to travel by low-floor bus, Service Route Traffic (SRT) or STS. Two different methods were chosen. Critical incidents were collected during participant observation, and by means of a pilot instrument based on the Enabler Concept independent environmental assessments were performed.Not all environmental details registered during the participant observations were in agreement with the independent environmental assessment, and different reasons for the disagreements were reported. In addition, participants travelling by STS gave information about what hindered them from using conventional public transport.The theoretical understanding behind accessibility assessments has benefited from the methodological challenges mapped out in this study. In order to interpret accessibility, the individual perspective as well as the population perspective are necessary, which means that complementary methods are needed.

Fuel cell drives for road vehicles

For fuel-cell driven vehicles, including buses, the fuel cell may be the main, determining factor in the system but must be integrated into the complete design process. A Low-Floor Bus design is used to illustrate this point. The influence of advances in drive-train electronics is illustrated as are novel designs for motors and mechanical transmission of power to the wheels allowing the use of novel hub assemblies. A hybrid electric power system is being deployed in which Fuel Cells produce the energy needs but are coupled with batteries especially for acceleration phases and for recuperative braking.

Evaluation of Low Floor Bus by Citizens of Elderly People and Disabled People, and Passengers

This paper aims to evaluate the Low Floor Bus services introduced in Amagasaki and Itami from the point of view of users, elderly and non-elderly people and disabled people. In order to accomplish the aim, we made the indices of degrees of satisfaction, importance and priority of improvement relating bus services.As a result, it was clarified that every user wants to improve the increase of the frequency of Low Floor Buses most strongly.

Bus Stop Design and Automated Guidance for Low-Floor Buses: Evaluation of Prototypes with Investigation of Human Factors

Low-floor vehicle design improves the accessibility of urban buses to people with reduced mobility. In France, on the basis of the experience gained from low-floor tramways, a system approach soon appeared necessary and the low-floor bus within the urban environment was considered. Described are the results of the research and development project initiated by the Grenoble network to reach efficient guidance solutions that would ensure minimal gaps at bus stops. Operating conditions of accessibility equipment on the vehicle (kneeling, access ramp) as well as driver capability to dock at the bus stop have been investigated. From the results, an improved bus stop was designed and two prototype systems—GIBUS visual aid and VISÉE guidance system—were conceived and tested. Evaluation of these during operation on a bus route in the city of Grenoble concentrated on assessing system performance and human factors so that recommendations could be drawn before implementation.

Accessible Low-Floor Bus: System Approach in France

Low-floor bus design makes urban buses more accessible to people with reduced mobility. In France, as a result of the knowledge gained from using low-floor tramways, the use of low-floor buses within urban environments was considered. Requirements of people with reduced mobility for easy access and the necessary operating conditions are described, followed by an examination of the requirements for such a system in France: bus/infrastructure interface (access ramp and docking aid), bus stop design, and wheelchair user safety.

Transit Service Design and Operation Practices in Western European Countries

Fundamental transit service design in a number of small cities in Western Europe, which have reputationally good transit systems, is discussed. This work was the result of a transit study tour sponsored by the Transit Cooperative Research Program of TRB. Key differences between transit design practice in Europe and the United States include longer distances between stops, superior customer information at bus stops, more frequent service, and downtown schedule coordination in the European systems. The combination of low-floor buses, off-board fare collection, long distances between stops, and multiple boarding doors on buses enables these systems to carry a large number of customers without deteriorating schedule speed. Several transit systems have used imaginative methods of providing service in low-density markets such as sparsely settled areas and evening and weekend transit service. These include the use of group taxis that travel between downtown and bus stops in the rest of the city. Compared with U.S. transit systems of comparable size, European transit systems are more technology driven. Even small cities have traffic-signal preemption systems, schedule adherence systems, and off-board electronic fare collection technology. Possible application of some of these techniques to transit practice in the United States is discussed.

Hybrid electric transit bus pollutes less, conserves fuel

This true low-floor bus prototype has the performance of a conventional diesel-powered vehicle with hardly any fumes. The authors discuss the design of this series hybrid bus, and in particular the propulsion system. Four independent AC drives, one integrated into each driven wheel, are used. They are powered by a battery assisted auxiliary power unit consisting of a downsized heat engine coupled to an alternator. The authors describe the tests carried out on this bus.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Don't Take a Step, Take a Low Floor Bus

Don't Take a Step, Take a Low Floor Bus