City bus systems in India have been witnessing a decline in service consumption and revenue despite having a high proportion of transit dependent passengers. Improving their performance and ...encouraging higher transit ridership are required for Indian cities to meet their mobility demands in a resource efficient manner. We present an objective framework to measure efficiencies of these systems and to carry out a disaggregated analysis of the key internal and external variables impacting their efficiency. A Data Envelopment Analysis (DEA) based approach was adopted for benchmarking the performance of eight city bus services. Three categories of performance efficiency i.e. service supply, consumption and revenue were measured using relevant input and output variables derived for the seven year study period between 2009-10 and 2015-16. The analysis identifies the best and least performing cities in each category and the potential reduction in resource consumption to improve their efficiency. Regression analysis of these efficiencies was carried out to establish correlation with external variables representing city size, land-use development characteristics and economic performance. The analysis identified low service consumption even in cities with high supply and revenue efficiency, highlighting the need for improved planning that enables demand oriented services. Cities also need to improve their service supply and revenues adequately to be efficient even as the cities grow in size and economy. The findings from this study provide policy and planning inputs to improve bus systems in other developing countries with similar public transport systems, city development and mobility characteristics.
The efficient coupling driving control is a key technique that affects both the fuel economy and drivability of the hybrid electric bus (HEB). However, the uncertainties resulting from the complex ...driving condition and the powertrain would affect the control performance. To solve this problem, this study proposes a novel control approach, which is elaborately integrated with multi-controllers under the consideration of properties of the city-bus-route and the hybrid powertrain configuration. First, a torque split strategy with the automated mechanical transmission (AMT) gear-shifting strategy is employed to adapt the driving intention quantified by fuzzy logic. Then the coordinated control mechanism is constructed through utilising the electric machine (EM) to compensate the response deviation of engine torque, meanwhile a robust controller is designed to withstand parameter perturbation and external disturbance existing in EM. Simulation results show that the operating points of the engine and EM are adjusted into the high-efficiency areas with the assistance of AMT gear-shifting, and the EM torque tracking performance especially when parameter perturbation and external disturbance appear. Moreover, the strategy adaptively distributed the driving torque in the predefined working modes for different driver's intentions. Thus, the efficient coupling driving of HEB might be implemented by the proposed method.
Toxic Emission During Road Tests of Urban Bus Magryta, Paweł; Grabowski, Łukasz; Barański, Grzegorz ...
Advances in science & technology, research journal,
01/2023, Volume:
17, Issue:
6
Journal Article
Open access
The article presents the results of toxic emissions in road tests of an urban bus. The object of the study was the Mercedes Connecto city bus. The results of toxic emissions were recorded in real ...time while bus drives with the use of the Semtech Ecostar exhaust gas analysis system. The study involved a planned bus SORT 2 test cycle. During the tests, the fuel consumption and exhaust gases such as CO2, CO, NOx, HC, NMHC, and O2 were recorded. The driving conditions in the study were constant (test cycles took place at the airport), exhaust gas temperature (hot engine) was also constant, etc. The results were based on average values from 5 test cycles for each test. The influence of electric load in the bus grid on the level of toxic emissions was measured. It has been proven that fuel consumption and CO2 emissions increased, which means a change in the value of components of toxic emissions. This fact evident from the increased CO emissions and decreased O2 emissions. Logically, the air-fuel mixture may have been enriched due to the increased demand for effective power generated by the engine crankshaft.
Engine braking, just when the vehicle consumes no fuel, is an important component of the energy balance. In such states, the bus loses its cumulated kinetic and potential energies but alternators ...recover a portion of these energies into electricity. Simultaneously, electricity consumption in the diesel-engine city bus is a key component of the overall energy balance. A total energy output of receivers can be more than 4 kW. This paper presents the research results on performance of a serial bus driving varied urban routes. The recorded and investigated parameters include a total amount fuel and electricity consumed and an amount of electricity generated. Engine braking states were calculated with a created algorithm. On average, 17% of electricity was generated by bus engine braking. The research results and investigation refer to the entire year.
•Driving cycle construction methods are studied.•A bus-station-based driving cycle segment division method is proposed.•An improved whole-trip-based bus driving cycle construction method is ...formulated.•The typical hybrid electric bus driving cycles using improved and regular construction methods are compared.
Intra-city buses have become an effective way to alleviate urban traffic congestion. Developing the driving cycle for an intra-city hybrid electric bus is of great importance for energy economy and emissions performances tests, as well as control strategy optimization to enhance fuel economy and reduce emissions. In the construction of the bus driving cycle using the adapted regular method based on kinematic segments with fixed time-steps, the transition of partial kinematic segments leads to velocity fluctuation, which does not reflect the actual driving characteristics. This study initially collects driving data from a hybrid electric bus in Shanghai, and constructs its typical driving cycle by the k-means clustering method. Considering the characteristics of frequent stopping and repetition during the bus driving cycle, the bus-station-based driving cycle segment division method and the whole-trip-based bus driving cycle construction method are proposed. A typical hybrid electric bus driving cycle is then constructed using the proposed methods. Finally, the typical hybrid electric bus driving cycles developed by two methods are compared and analyzed. The 2-norm value of the characteristic parameter error vector is decreased from 0.249 for the typical hybrid electric bus driving cycle based on the adapted regular method to 0.163 for the improved method. It is shown that the whole-trip-based bus driving cycle construction method reflects the actual driving characteristics better, has lighter computation burden, and lays the foundation for the development of an adaptive control strategy for the hybrid electric bus as well as tests of its energy economy and emissions.
This paper discusses the methodologies to investigate the efficiency of on-board electricity generation in the city bus. The research object, i.e. the Mercedes Conecto was tested under steady ...conditions. A chassis dynamometer, i.e. the MAHA LPS 3000 LKW provided the same conditions during the entire research. The paper presents the samples of the measurements performed at a single operating point of a given crankshaft speed and torque. This operating point was specified in line with the guidelines for the WHSC test. In our study, an electrical load was changed with an extra receiver, or a light bulb, at a fixed amount of fuel. The electrical loads were 0.4 kW, 1.6 kW and 2.8 kW. The research results enabled us to specify the amount of fuel to generate 1 kWh of electrical energy.
In this study, the AVL Cruise is implemented to simulate driving parameters including the driving path, the power loss on engine accessories, the gear-shifting scheme and the engine's fuel cut-off ...strategy influencing the bus fuel efficiency and emission. The Mercedes Conecto LF city bus using a diesel engine with Standardised On-Road Test Cycles was firstly simulated and compared with available literature. The application of hydrogen fuel was then examined and its result was compared with the diesel fuel on the specific fuel consumption. In addition, the driving cycles in Bangkok were simulated. The results show the pattern on both driving cycles with different fuel are similar, however, the fuel consumption of H2 is significantly less than in the case of Diesel. Moreover, it is also evident that the SORT driving cycle cannot represent the heavy traffic of Bangkok.
Battery electric city bus model has been created and validated with measurement results from a full-scale city bus prototype. The model utilises multi-physics modelling approach with multiple-domains ...from friction-tyre and transmission model to electrical drive and a simplified battery model. For the electrical drive model, four approaches to model the losses were studied. The modelled and measured motor torque, speed, current in the battery and inverter, and the bus speed were compared under two bus line driving cycles using three payloads. The simulated results were in good agreement with the experimental results; the error between the simulated and measured energy consumptions was 1.5% with the most accurate model.
Background and Objective: Bus drivers, the same as other drivers, are prone to unsafe behavior, and accidents are associated with driver’s risky behavior. Moreover, traffic accidents are different in ...intra-city and intercity routes, which can be at least partly due to the driver’s behavior. Therefore, this study aimed to compare the dangerous driving behavior of intra-city and intercity bus drivers. Materials and Methods: This descriptive and analytical study was performed on 107 intra-city and 99 intercity bus drivers in the city of Zanjan, Iran, using demographic characteristics form and the Dula Dangerous Driving Index. Eventually, the collected data were analyzed in SPSS software (version19) through a t-test, chi-square test, and linear regression. The p-value less than 0.05 was considered statistically significant. Results: The mean weekly working hours of intra-city bus drivers are significantly higher than those of intercity bus drivers (P<0.05). Moreover, the mean of the dangerous driving index and its sub-scales, except for aggressive driving, were higher in intra-city bus drivers, compared to intercity bus drivers (P<0.05). In addition, the weekly working hours variable had a negative impact on the risky driving score in the intra-city driving routes; however, it had a negative impact on the emotional/cognitive driving subscale and a positive impact on the drunk driving subscale in the intercity driving rout (P<0.05). Conclusion: Despite the lower number of fines and deaths on intra-city routes, it is necessary to take more serious control measures for the risky behaviors of bus drivers. These include developing intervention programs to manage bus drivers’ working hours in order to reduce fatigue and raise drivers’ awareness for less risky driving behaviors.
City buses are one of the main means of public transport in cities. As they move in a limited and densely populated area and are intensively exploited, it is particularly important that they are ...environmentally friendly. There are many ways to reduce emissions from city buses, including the use of hybrid propulsion. Another way is to use low-emission fuels. This article presents the results of the emission tests of an 18 m articulated city bus with a serial hybrid drive fuelled comparatively by conventional diesel fuel and oxygenated fuel containing 10% v/v of triethylene glycol dimethyl ether (TEGDME). The emission tests were carried out during the actual operation of the bus on a route in Poznań (Poland) and over the SORT cycles. The obtained test results were compared also with the results obtained for a conventional bus. The reduction in emissions of some exhaust components was found when the hybrid bus was fuelled with oxygenated fuel during its actual operation on the bus route. There was a reduction in CO emissions by ~50% and NOx emissions by ~10%. Almost identical levels of PM and HC emissions and smoke opacity were observed for both fuels. In the SORT cycles, the differences in the emissions obtained for both types of fuel were small. In general, for the hybrid bus, a lower influence of oxygenated fuel on emissions was recorded than for the conventional bus.
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