2,024 research outputs found

    Framework for integrated planning of bus and paratransit services in Indian cities

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    Public transport services in India and many other developing countries are provided by a combination of formal-Government led public transport systems and informal paratransit or Intermediate Public Transport (IPT) systems, which offer shuttle services along high demand corridors with passengers boarding and alighting at multiple points. Despite limited Government support, paratransit systems continue to thrive in many cities serving a crucial shared mobility need of users, without which cities would have more private vehicle usage. Due to their informal nature and the perceived competition to formal public transport systems, they have traditionally been either excluded from the public transport planning processes or designed as a feeder service to the formal transit system. The current thesis recognises paratransit’s role in serving end to end travel demand needs, particularly in developing economies with limited public transport supply and not just being a feeder to the formal public transport system. Hence, we develop an integrated planning framework that enables formal and informal public transport systems to operate as complementary systems towards meeting the mobility needs of the city. We proved an integrated planning framework based on comprehensive understanding of the demand and supply characteristics of both formal and informal systems which currently operate independently to realign services and complement each other. The tactical planning stage of public transport planning i.e. frequency setting was identified as the ideal stage of planning for integration of the two types of services. This will ensure continuity of their existing route networks and at the same time allow for paratransit services’ flexibility to switch operations between routes. Visakhapatnam, a representative medium sized Indian city with a significant presence of formal public transport in the form of city bus services and paratransit services provided by three-wheeler auto-rickshaws with a seating capacity of three to six passengers, was selected as the case city to demonstrate the methodology. A household survey based data collection and analysis methodology was adopted to analyse the socio-economic and travel demand characteristics of city bus and paratransit users. The variables impacting users’ choice between these two systems were derived through binary logistic regression. The high frequency and low occupancy paratransit systems were more popular among shorter trips, while longer trips preferred the fixed table bus systems. The operational characteristics of bus and paratransit systems were derived through a combination of primary surveys with paratransit operators and secondary data on the city bus operations. Data regarding their network of operation, services offered, passenger demand and revenue generated were collected for analysis. Buses perform a service function in the city by operating throughout the day and on a wider network, while paratransit operates with a profit motive only on high demand corridors and during peak hours. A Data Envelopment Analysis (DEA) based methodology was adopted to compare the performance efficiency of the two systems using a set of input and output indicators that define the performance of the two systems. Paratransit operations were identified to be more efficient compared to buses, due to their demand responsive operations. The lower efficiency of buses was also due to their service obligation to the city to provide affordable services throughout the day, even in areas with low demand. A bi-level transit assignment and frequency optimisation framework is developed to integrate formal bus and paratransit services. The lower-level of the model solves for the multi- modal transit assignment problem while the upper level solves for the integrated frequency optimisation problem. The transit assignment problem was solved from the users perspective i.e. to minimise their travel time through the user-equilibrium method. The frequency optimisation problem was solved using an integer programming formulation with the objective of minimising operational cost of bus and paratransit systems while meeting constraints like the travel demand on any link. The outputs from the optimisation exercise were used to quantify the impact of the public transport system at various levels i.e. users total travel time spent in the system, operators cost of providing the services and the overall impact on the society by estimating its road space requirement and emissions. Alternative user demand and transit supply scenarios were tested to assess their impacts on the society. The results show significant operational cost benefits of an integrated transit assignment and frequency planning approach where paratransit provides demand responsive services for short distance trips while formal public transport provides fixed schedule services on with broader network coverage. The analysis established the complimentary role played by bus and paratransit systems in meeting users travel demands. Therefore, it is recommended that cities harness both the systems towards meeting increasing travel needs of developing economies. Formal transit will continue to be the core of the public transport system, providing fixed route services, while paratransit can augment its capacity on high demand corridors and during peak hours. The planning and frequency optimisation framework developed in this thesis can help cities in identifying the modal-mix of fixed route public transport and on-demand services

    Battery SMART charge controller/combined co-gen grid connected inverter design and simulation

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    Electricity generation and distribution is undergoing significant change under the influences of energy security, climate change, technological development, and economics. Technologies that have introduced two-way power flow onto a distribution grid that was designed for one-way power flow are creating challenges and opportunities for innovation in the electricity distribution sector. These technologies include solar photovoltaics (PV), wind turbines, and battery energy storage systems (BESS). As the newest technology, BESS present opportunities to both the electricity distribution network service provider (DNSP) and the consumer. This dissertation focused primarily on the consumer side of the switchboard, modelling and analysing the economics and some of the technical issues for an economic-mediated battery controller as part of a grid-tied residential hybrid renewable energy system (HRES) that consists of a BESS, 1 kW wind turbine, and 10 kW PV array. The geographical context of this project is Nambour, Queensland; PV and wind power calculations were based on Nambour’s meteorological history. Residential energy consumption was modelled as a ‘typical’ Nambour residential customer. The technological context was such that costs and choices applied at mid-2016. The tariff context used was the recently introduced TOU tariff 12, which played a significant role in the timing and logic development of the battery charge controller algorithm. From a technical standpoint, the charge controller algorithm was a major achievement of the present work. In developing the algorithm, it was found that the use of data from individual system components could be used to formulate the optimum mix of power sourced from or sunk to both the grid and the BESS. The output of this formulation was then demonstrated as a data input used for the control of the switching patterns of the BESS power electronics, a two-quadrant DC-DC converter (chopper). The other major achievement of the current work was the finding that although BESS economics continue to improve, they generally still need to achieve further cost reductions in order to realise economic feasibility for the modelled context. It was also found that economic feasibility is more likely to be reached more quickly under conditions of high energy consumption, high inflation, high peak TOU tariff, and low discount rate

    Multimodal pricing and the optimal design of bus services: new elements and extensions

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    This thesis analyses the pricing and design of urban transport systems; in particular the optimal design and efficient operation of bus services and the pricing of urban transport. Five main topics are addressed: (i) the influence of considering non-motorised travel alternatives (walking and cycling) in the estimation of optimal bus fares, (ii) the choice of a fare collection system and bus boarding policy, (iii) the influence of passengers’ crowding on bus operations and optimal supply levels, (iv) the optimal investment in road infrastructure for buses, which is attached to a target bus running speed and (v) the characterisation of bus congestion and its impact on bus operation and service design. Total cost minimisation and social welfare maximisation models are developed, which are complemented by the empirical estimation of bus travel times. As bus patronage increases, it is efficient to invest money in speeding up boarding and alighting times. Once on-board cash payment has been ruled out, allowing boarding at all doors is more important as a tool to reduce both users and operator costs than technological improvements on fare collection. The consideration of crowding externalities (in respect of both seating and standing) imposes a higher optimal bus fare, and consequently, a reduction of the optimal bus subsidy. Optimal bus frequency is quite sensitive to the assumptions regarding crowding costs, impact of buses on traffic congestion and congestion level in mixed-traffic roads. The existence of a crowding externality implies that buses should have as many seats as possible, up to a minimum area that must be left free of seats. Bus congestion in the form of queuing delays behind bus stops is estimated using simulation. The delay function depends on the bus frequency, bus size, number of berths and dwell time. Therefore, models that use flow measures (including frequency only or frequency plus traffic flow) as the only explanatory variables for bus congestion are incomplete. Disregarding bus congestion in the design of the service would yield greater frequencies than optimal when congestion is noticeable, i.e. for high demand. Finally, the optimal investment in road infrastructure for buses grows with the logarithm of demand; this result depends on the existence of a positive and linear relationship between investment in infrastructure and desired running speed

    Optimisation of Rail-road Level Crossing Closing Time in a Heterogenous Railway Traffic: Towards Safety Improvement - South African Case Study

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    The gravitation towards mobility-as-a service in railway transportation system can be achieved at low cost and effort using shared railway network. However, the problem with shared networks is the presence of the level crossings where railway and road traffic intersects. Thus, long waiting time is expected at the level crossings due to the increase in traffic volume and heterogeneity. Furthermore, safety and capacity can be severely compromised by long level crossing closing time. The emphasis of this study is to optimise the rail-road level crossing closing time in order to achieve improved safety and capacity in a heterogeneous railway network. It is imperative to note that rail-road level crossing system assumes the socio-technical and safety critical duality which often impedes improvement efforts. Therefore, thorough understanding of the factors with highest influence on the level crossing closing time is required. Henceforth, data analysis has been conducted on eight active rail-road level crossings found on the southern corridor of the Western Cape metro rail. The spatial, temporal and behavioural analysis was conducted to extract features with influence on the level crossing closing time. Convex optimisation with the objective to minimise the level crossing closing time is formulated taking into account identified features. Moreover, the objective function is constrained by the train's traction characteristics along the constituent segments of the rail-road level crossing, speed restriction and headway time. The results show that developed solution guarantees at most 53.2% and 62.46% reduction in the level crossing closing time for the zero and nonzero dwell time, respectively. Moreover, the correctness of the presented solution has been validated based on the time lost at the level crossing and railway traffic capacity consumption. Thus, presented solution has been proven to achieve at most 50% recovery of the time lost per train trip and at least 15% improvement in capacity under normal conditions. Additionally, 27% capacity improvement is achievable at peak times and can increase depending on the severity of the headway constraints. However, convex optimisation of the level crossing closing time still fall short in level crossing with nonzero dwell time due to the approximation of dwell time based on the anticipated rather than actual value

    Contributions to behavioural freight transport modelling

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    POTEnCIA model description - version 0.9

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    This report lays out the modelling approach that is implemented in the POTEnCIA modelling tool (Policy Oriented Tool for Energy and Climate Change Impact Assessment) and describes its analytical capabilities. POTEnCIA is a modelling tool for the EU energy system that follows a hybrid partial equilibrium approach. It combines behavioural decisions with detailed techno-economic data, therefore allowing for an analysis of both technology-oriented policies and of those addressing behavioural change. Special features and mechanisms are introduced in POTEnCIA in order to appropriately reflect the implications of an uptake of novel energy technologies and of changing market structures, allowing for the robust assessment of ambitious policy futures for the EU energy system. The model runs on an annual basis with a typical projection timeline to 2050.JRC.J.1-Economics of Climate Change, Energy and Transpor

    A simulation study of the deflection of the slab and at subgrade by a high-speed train

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    As the demand for rapid transport and higher frequency rail services around the world is increasing, greater stresses are induced on the track, thus the necessity for a sustainable and durable railway structure is essential. To meet these demands it is seen that slab track construction is generally preferred for High-Speed Railways (HSR) as opposed to the conventional ballasted track as the slab track can sustain higher dynamic loading with less maintenance. In line with this research, a study on the development and application of a 3D structural model using ABAQUS software is carried out to evaluate the dynamic behaviour of HSR slab track. This research aims at evaluating the continuously fastened Balfour Beatty Embedded Rail Track System (ERS) and comparing it with the RHEDA (RTS) slab track system, which is discreetly fastened. The modelled rail tracks consist of a rail fastened onto a slab laid on a suitable foundation. The foundation consists of a Subbase Layer (HBL) placed on a Capping Layer (FPL) overlaying the subgrade soil. This thesis looks at the findings of dynamic analysis of various parameters which are affected during the high-speed passage of trains. Constant speeds are applied to a moving load as a part of dynamic analysis. Parametric studies are performed for CBL stiffness, soil stiffness and CBL thickness. The motion speeds are also changed to see its effect on the rail track. This study will shed light on the dynamic behaviour of ETS and RTS with changing parameters
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