Railway Engineering
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Item Accessibility and Suitability Analysis of Light Rail Station Location by using (AHP) and GIS: Case study on Existing and Future Expansion of Addis Ababa LRT Respectively(Addis Ababa University, 2016-12) Gomeju, Taye; Alemayehu, Ambo (PhD)Addis Ababa city metropolitan constructed phase one light rail transit line aiming to solve current transport problem. This Light Rail Transit is assumed to transport 80,000 passengers per hour per direction. For the system to hit the targeted objective on the proposed line, stations have to be positioned at a place where it can attract maximum users which enable the system to solve the problem and to be independent of subsidies. This is all about integrating Light rail system with other transport modes in Addis Ababa. This paper examines the existing station sites accessibility to other transportation modes or access mode, and adopts Geographic Information Systems and Multi-Criteria Evaluation technique to carry out suitability mapping of station locations for phase two light rail transit route in Addis Ababa. For the station suitability analysis, eleven different criteria were identified and each criterion was weighted using Analytical Hierarchy Process AHP. The output of Analytical hierarchy process was used as an input for geographic information system GIS special analysis. Finally, based on these criteria requirements using overlaying, Euclidean distance calculation, Rasterisation, buffering reclassification and weighted overlay analysis, the station site suitability map was generated. The map revealed five classifications as: “less suitable”, “suitable”, “moderately suitable”, highly suitable and “extremely suitable”.Item Adaptation of Railway Station Design Parameters For Ethiopia National Railway Network(Addis Ababa University, 2015-02) Missa, Tegene; Matias, Kabtamu (Mr.)Railway transportation, which is needed in the achievement of effective development, is an efficient, cost-effective and it is environmental friendly transport system. An important subject in the planning of a new railway line is the design of the railway stations since they affect the capacity, flexibility and the safety of the rail transport system. However, Ethiopian railway transport has no standardized guidelines to design the railway stations. The main objective of this thesis is to adapt station design parameters standards for Ethiopia national railway system by comparison of (AREMA, Chinese and Ethiopia standard proposed by Russian) based on Ethiopian topography, climatic condition, economy and interoperability to other countries. Hence, this study helps to provide: safe, cost effective and convenient access to train services, and to make convenient operation and management of the station and clear circulation routes with minimum travel distances. In this study an attempt was made to framework for national railway station design specifically station locations along the route and track and platform technical aspect for Ethiopian national railway network. To achieve the objectives the research had a methodology of a task involving literature review; comparison of different countries standardization practice, and then adaptation of station design parameters for Ethiopia on the basis of topography, and climatic conditions. In conclusion, economic and topographic aspect of station locations, track and platform technical aspect are basis for identifying station design parameters for Ethiopian national railway system. In the planning of a new railway line it has to be decided where stations should be located and where in the cities. Those decisions are governed by factors such as topography. In addition this capacity (demand), costs, city planning (future developments) and travel time requirements are factors to locate stations. In track and platform technical aspect; Number of arrival departure tracks, placement of platforms in relation to tracks, gradient in station and platform dimension (length, width and height) are appropriate parameters for Ethiopia national railway station design.Item Adaptation of Station Design Parameters for Addis Ababa Light Railway in Ethiopian Context(Addis Ababa University, 2018-01) Kaleab, Tesfaye; Mathias, Kabtamu (Mr.)Station is a basic production unit of railway transportation, integrating technical equipment relating to transportation. For the last couple of years investigations have been conducted in Ethiopia in railway site selection. One of that is the Addis Ababa light railway, where two alternative rights of way are seen. That is north- south corridor and East –west corridor of Addis Ababa which is about 34km. An important subject in the planning of a new railway line is the design of the railway stations since they affect the capacity, flexibility and the safety of the rail transport system. The main objective of paper is to investigate how stations can be designed to align with the proposed high speed railway concepts on the line of the light railway based the topography, demography, climatic and economic conditions of the country. The focus in the report is to adapt parameters of station design and investigate how they are affected by the high speed railway concepts. This paper consists of a literature study similar to the subject. The knowledge gained is then used to suggest possible station platforms, station safety. Some aspects of station design that are investigated in the literature study are platforms, platform safety issues, necessary dimensions of platforms and stations. It is concluded that the spacing of station and dimension of station (base width and length, plate form of station) is optimized in consideration of satisfying all passengers and the optimization analysis is need in estimation of cost of station. Therefore, sizing station is critical and designers should err on the side of safety when determining the size of the station.Item Adaptive Terminal Sliding-Mode Control for Speed Tracking of Multiple High Speed Train(Addis Ababa University, 2022-04) Liya, Koshana; Celestin, Nkundineza (PhD)In today‟s world, the railway transportation entered into the era of high speed. Which means the concern becomes more of to travel faster and safer. High speed trains are a train with a maximum operating speed of more than 200 km/h. Automatic train operation system is an operational safety enhancement device used to help automate the operation of the high speed trains. This system does its controlling function based on controllers which is embedded on it. But, due to some influencing factors which reduce the performance of the controllers which embedded on ATO like; parameter uncertainties, unknown model parameters, actuator effectiveness loss, coupler effect and external disturbance, until know there is a limitation in controllers to attain finite time convergence of the tracking error to the equilibrium point rather than achieving asymptotic convergence, that means stability within finite time is not guaranteed. In real time operation of high speed trains (HSTs), stability within finite time interval is desired instead of the asymptotic stability, as it is more physically realizable than concerning infinite time. In this paper, adaptive terminal sliding-mode control scheme was developed for finite time stable speed tracking control for high speed trains with unknown parameters of a model, parameters uncertainties, actuator effectiveness losses, coupler effect and external disturbance. In this paper the train system is modeled as a multi-point mass model and considered the in-train forces between the adjacent cars which are the effect of couplers. To attain stability within in a finite time terminal sliding-mode control is proposed and introduced for multiple high speed train system that drives the dynamical system of a tracking error to the predesigned sliding surface within defined time and thereafter sustain a sliding motion on it. For online estimation of unknown parameters of the model and the actuator fault compensation term adaptive technique is designed and cooperates with a terminal sliding-mode control. Saturation function is used to eliminate the chattering problem caused due to the terminal sliding mode control. Lyapunov theory is used to demonstrate the stability of a closed-loop train system. Lastly, to demonstrate a performance of the controller Matlab/Simulink environment is used. Finally, the system response settles within 3.134ms and zero steady state error is attained. So, the main objective of the paper, stability in finite time is achieved with good tracking accuracy. To realize the strong robustness of the proposed controller, its performance was demonstrated for different scenarios and obtained good results.Item Addis Ababa City Light Railway Transit Speed Profile for Optimum Train Drive: Case of Line from Menelik Square to Kality(AAU, 2014-08) Abebe, Teklu; Mengesha, Mamo (PhD)Optimum train driving is the key aspect of railway transportation development and depends on energy consumed, passenger comfort and punctuality. In this thesis three mathematical models have been developed considering nearly all traction mechanics and track information to generate appropriate speed profile. The first problem solved is minimization of energy consumed whereby the given journey must be completed on the allocated time. The second problem is minimization of journey time to complete the given journey; here the maximum energy consumed (the drive rating not to be exceeded) for fastest train drive is taken as one of the constraints. The third problem is designed to have different speed profile for different traffic condition ranging from high to low exempting the two extremes. In order to generate appropriate speed of the train at each discrete point, we used genetic algorithm with Deb’s constraint handling technique. Finally, we implemented the problems for North to South line of Addis Ababa light railway transit. The result obtained from simulation helps the driver to attain the required driving performance by driving the train with the respective speed profile.Item Addis Ababa Light Rail Transit Internal Trip Production Forecasting(AAU, 2014-09) Digafe, Tadesse; Birhanu, Beshah (PhD)This study mainly focuses on the Addis Ababa Light Rail Transit (AALRT) estimation of residential based person internal trips which unless analyzed can affects the project justification during the early stage of project installation, transportation planning during operation stages, identification of markets, service planning, facility assessments and revenue estimations. To estimate the trips the required primary and secondary data are collected, the primary data on locations closest to LRT routes are collected with a direct observation and interviewing of government officials and the secondary data on socio-economic data, census data and land use data are collected from various sources such as Central Statistics Authority, Addis Ababa Transport Authority and Addis Ababa City Plan Institute. The data gathered are analyzed using the Land Activity Rate or Land Use Method of trip based model for the base year trip production calculation and Growth Factor Methods for future trip projection calculations. the land activity rate is used to determine the total land areas covered by the LRT routes and the Institute for Transportation Engineers (ITE) standard is used to determine the trips per hectare produced and finally the growth factor method is used to project the trips for future times. Based on these models the numbers of trips are calculated both on North-South and EastWest LRT routes as a minimum and a maximum values in interval for the consecutive five years. The North–South route forecasting shows a minimum of 603,159 person trips per day and a maximum of 2,031,691 person trips per day whereas the East-West route forecasting shows a minimum of 1,124,988 person trips per day and a maximum of 3,789,434 person trips per day generated after five years in 2019G.C.Thus from the forecasted result of residential based internal trip production of the coming five years, the Ethiopian Railways Corporation (ERC) will be able to carry out the supply side facility estimation and future revenue projections so as to make the company responsive for the changes made on the travel needs.Item Addis Ababa Light Rail Transit Signaling System Design Analysis(Addis Ababa University, 2014-08) Tebebu, Terefe; Yalemzewd, Negash (PhD)The Signal System, which includes the functions of signal protection, grade crossing protection, and traffic signal coordination, shall be designed to allow light rail transit vehicles to meet the required line capacity, while providing a safe and operationally flexible system. Light rail shall operate in dedicated right-of-way or share the street with existing traffic. The dedicated portions of right-of-way shall use conventional fixed color light signals for train separation and safe braking distance. In view of that, in this thesis work the existing Addis Ababa LRT signaling system is analyzed. Strong sides and limitation of the existing design are discussed. And it is found that the signaling design on the line constructed ground has limitations according to safety, operational efficiency and other factors which are discussed well. Afterwards different design approaches will be presented and CTCS level 0 is chosen according to parameters stated. Therefore, on this section the design will be made to implement Automatic Block Signaling, wayside signals and cab signaling systems. Then braking distance of each stations are calculated so as the wayside signals are placed on safe locations. In order to calculate the operational efficiency the headway time between trains calculated. The speed limit of all necessary curves, switches and turnout are calculated and the average speed of the system is obtained. Finally the new design versus the existing design is compared based on safety, operational efficiency, cost, energy consumption and passenger satisfaction issues. And it is found that the new design improve headway time by 63.84% and improves the average speed by 63.97% that leads the system with new design is more efficient than the existing design.Item Adopting Freight Demand Forecasting Model for Addis Ababa-Djibouti Railway(Addis Ababa University, 2016-10) Arefeayne, Amare; Birhanu, Beshah (Assoc. Prof.); Biniyam, Ayalew (Mr.) Co-AdvisorFreight transportation is an essential component of any economic activity which makes a continuous change as a result of growth but many economic activities depend on traffic congestion and truck travel time along the origins and destinations which makes series problem mainly for land locked countries like Ethiopia. This is because government and organization pay undesired tax for the stay of goods at the port. In order to solve this problem different countries use different forecasting models which are designed to predict the future need of the country. This thesis work identifies major freight forecasting projection models, discusses those models, chooses the better model based on the merits and demerits of each model and forecasts with one of the classic freight forecasting model which is called four-stage aggregate model (hybrid with its own parameters) to show how it works in the context of Ethiopia by taking traffic congestion as a main problem. As part of this work trip generated using growth factor and linear regression and mode choice along the path has been done by incorporating the truck traffic count, commodity tonnage share and an expense given to each item. This hybrid four-stage aggregate model which begins with trip generation step and gives a result of 3,351,406 trips when working with Annual Growth Factor (AGF) and 57,974 trips with linear regression method. And a comparison between this a model and a model forecasted by ERC has been compared and found ERC model which generates 119,419 trips nearly comparable with linear regression method even though the parameters used here are different. From the total number of trips generated trains took 79 percent mode share and truck took remaining modal share. The distribution and an assignment step is not done because, the demand investigating here focuses only origin and destination. Finally the thesis find out forecasting with four-stage aggregate model(Hybrid model) which uses traffic counts, commodity tonnage share and an expense growth rate given for each items as input parameter is better model in order to generate number of trips along the line. This is because import and export tonnage rates can easily affected by the influence of economy, industrial location patterns, globalization of business, fuel prices,cumulatively can affect the traffic congestionItem Aerodynamic Characteristics and Aerodynamic Shape Optimization of Ethiopian National Train, Case Study on Addis Ababa Dire Dawa Passenger Train(Addis Ababa University, 2014-10) Mamo, Nigusie; Demiss, Alemu (PhD)The aim of this study is to study and improve the aerodynamic performance (drag coefficient, lift coefficient, etc.), to reduce the energy consumption and checking the operational safety of the train against cross wind. The area of the study mainly concentrated on the frontal aerodynamic drag analysis and related characteristics of Ethiopian National Train (ENT).In particular Addis Ababa Dire Dawa 120 km/hr. speed passenger train is used for the analysis. The computational fluid dynamics (CFD) analysis simulation method is used for the study. To improve aerodynamic drag performance shape optimization of train head is done using multi-objective approximation integrated with computational fluid dynamics and response surface methodology. For the CFD full scale analysis ANSYS fluent 12.0 using steady RANS method is used. For the study of the stability against cross wind the wind with yaw angle -30 to 60 degree is analyzed. Results shows that the train has poor aerodynamic performance at this speed and shape which has around 0.93 drag coefficient. Also has poor performance against cross wind, hence care must be taken especially on the curves and embankment. After shape optimization drag coefficient of around 0.79 is obtained which is close to minimum recommended result (0.5).This result in reduction of more than 15% drag coefficient and this shows reduction in energy consumption.Item Alternative Wireless Communication System Design for AA-LRT Railway Tunnels at Piassa(Addis Ababa University, 2015-04) Mehari, Belete; Yalemzewd, Negash (PhD)Railway transport is effective and reliable only if it has best communication and signaling system with safety, reliability and good quality of service which are maintained by railway management and communication system. By implementing latest technologies for railway communication railway transportation can be made safer, efficient, and more accessible. This research work focuses on the study of Ultra wide band (UWB) radio based wireless communication system as an auxiliary or alternative communication system for Addis Ababa Light rail transit (AA-LRT) tunnel at piassa (Gyorgis), whose main task is to maintain an uninterrupted data transmission between train driver to wayside controller. The much larger bandwidth of ultra-wideband allows a very high data rate (up to maximum 480 Mbps), which is beneficial in case of emergency in railway networks. This research studied the rectangular shaped railway tunnel environment as wireless channel by considering ray theory model of wave propagation (modal analysis and ray tracing) and the effect of the curvature of the tunnel on the wave propagation. In this thesis work the frequency response, channel impulse response and path loss for different distances between transmitter and receiver and also the effect of fading over the channel is evaluated. The evaluations have been used to model the effects of tunnel propagation, including curves inside the tunnel. Then three standard wave shapes has been tested with the modelled channel to observe the phase shift and time delay provided by the considered channel model which behaves as a multipath fading channel with additive white Gaussian noise. Lastly to check the quality of reception bit error rate performance has been evaluated for BPSK and OOK modulation techniques. Finally, a complete propagation model combining both modal analysis and ray tracing has been applied to predict the propagation loss inside the tunnel. So to maintain the continuity of communication it needs to install ultra-wideband trans-receiver over the specific interval.Item Analysis and Design of an Optimized Automatic Fare Collection System for Addis Ababa Light Rail Transit(Addis Ababa University, 2019-08) Mola, Ayenew; Yihenew, Wondie (PhD)Recently, everything in the world becomes smart and digitalized. Many advances have been made in the transportation sector too. However, railway transport in Ethiopia has been an area where such new advances have turned their faces out. Therefore, this paper, will introduce an Automatic Fare Collection system (AFC) to up bring the railway transportation system in Ethiopia to the best standard. In addition, this paper will focus on different ways of implementing AFC, which will be suitable for AA-LRT. AFC is one of the important technologies in railway transportation around the world. Different countries use different ways of implementation of AFC to their railway transportation. One of the aims of this paper is to study different implementation mechanisms of countries and analyses the best and suitable standard for AA-LRT. The cost analysis should also be considered when such kinds of technologies are implemented. Nowadays, in AA-LRT every train is controlled by a conductor. The conductor will collect money from each passenger and issues tickets and the printed paper or tokens are used as tickets. This process needs man power and the passengers whom are utilizing the transportation services will not be satisfied. Because, they will wait a lot of time on the queuing to get ticket from the cashier. In the proposed system, every AA-LRT stations have one or more RFID (Radio-Frequency Identification) Reader. RFID is a technology whereby digital data encoded in RFID tags or smart labels are captured by a reader through radio waves. The Reader senses the RF signals coming from the passenger identification card and thus recognizes the entry, existence and exit of the passenger. Based on the signals from the card is cut off, the fare of the journey is calculated and is deducted from the passenger’s account, which is linked with the backend system. The RFID card will recharge in different ways, it may recharge from stations, mobile account and/or bank account. The system will deliver an end-to-end solution for fare collection, ticketing, and payments that provides secure and faster transactions, more convenience and smooth passenger flow during peak hours, and efficient collection of fare ensuring no fraud takes place.Item Analysis and Design of Pre-stressed Concrete (PSC) Girder Railway Bridge(Addis Ababa University, 2016) Temesgen, Dola; Abrham, Gebre (PhD)A bridge is a structure that crosses over a river, bay, or other obstruction, permitting the smooth and safe passage of vehicles, trains, and pedestrians. Bridge construction today has achieved a worldwide level of importance. Bridges are the key elements in any road network. Use of concrete girder is gaining popularity in railway bridge engineering because of its better stability, serviceability, economy, aesthetic appearance and structural efficiency. The structural behavior of box girder is complicated, which is difficult to analyze in its actual conditions by conventional methods. In this project a simply supported Box Girder Bridge made of pre stressed concrete is analyzed for moving loads following different standards and specifications. The Ethiopian Government has constructed Addis Ababa light rail transit (AALRT) project and also has started the construction of national railway project for different corridors of the country is under construction with CREC (China Railway Engineering Company) and another foreign (international) contractors. The railway bridge commonly contains two types of tracks which are ballasted and slab track. This project principally emphases on the superstructure of bridge supporting track rails attached to the bridge to support trains. Thus, this project has attempted to develop the Micro soft Excel program to analyze and design the Pre-stressed Concrete (PSC) Girder Railway Bridge for any span lengthItem Analysis and Design of Simply Supported Pre-Stressed Precast-Cast In-Situ Concrete Composite Railway Bridges: Comparison of Ballasted and Slab Track Alternatives(Addis Ababa University, 2015-03-12) Ashenafi, Oycha; Asnake, Adamu (PhD)Bridge is one of the most important components of railway line for development of transportation. It is known that Addis Ababa light rail transit project construction started two years ago. Also the construction of national railway project started. In these projects, the construction of bridges need highly skilled man power and highest construction cost. The railway bridge commonly contains two types of tracks which are ballasted and slab track. There is a difference in construction cost of bridge between ballasted track case and slab track case. Thus, this study has attempted to analyze, design and compare both ballasted and slab track type laying on the surface of bridge. This study mainly focuses on the superstructure of bridge supporting track rails attached to the bridge to support trains. The intention of this thesis is therefore to compare the construction cost of railway bridges with ballasted and slab track cases and to select the economical track type laying on the surface of railway bridge. Finally, from the overall analysis result of this thesis, the study conclude that slab track is economical than ballasted track for span length greater than 15m. On the other hand, ballasted track seems economical than slab track for span length less than 15m.Item Analysis and Improvement of Secondary Suspension Effects on Ride Comfort of Passanger Railcar (Case of Addis Ababa Light Rail Transit Service)(2021-10) Biniam, Ejara; Nkundineza, Celestin (PhD)Speed and track irregularities are the main causes of vibrations in rail vehicles. They bring a discomfort, fatigue and motion sickness to passengers depending on its frequency content. In this thesis the analysis and improvement of the secondary suspension effects on a passenger ride comfort of rail vehicle by considering the current random track irregularities are evaluated via the Sperling ride index. The current track irregularities data were collected from Addis Ababa Light Rail Transit Service (AALRTS) then converted to time domain and curve fitted using sine functions. The half car model of a vehicle with two bogies, two suspension levels, and a flexible carbody for one car is considered for mathematical modeling of the vehicle vibrations. The response due to pitch and bounce were numerically analyzed using MATLAB / Simulink and Universal Mechanism multibody dynamic simulation software (UM-MBS). The results obtained from two numerical simulations matched between each other. The results show that bounce vibrations affect more the ride comfort than pitch vibrations and as the speed increases the ride comfort worsens according to Sperling ride index evaluations. In addition to these analyzes, if the secondary suspension damping ratio falls between 0.1 and 0.3 the ride comfort is improved. Finally, optimizations of suspension parameters were done for worst track irregularities scenario by using MATLAB/Simulink/ Response optimization tool which led to reducing the ride discomfort significantly than the current suspension parameters. The evaluations concluded that the AALRTS vehicle vertical response is at good conditions with current track irregularities. The ride comfort is improved by 9.87%, 14.62%, and 15.17% at the center of the carbody, above bogie front and above rear bogie respectively.Item Analysis and Prediction of Track Geometry Degradation: Case study of Addis Ababa Light Rail Transit(Addis Ababa University, 2021-06) Aisha, Kabange; Daniel, Haile (PhD)Development of good maintenance policy requires better understanding of the long-term behavior of railway track systems. Addis Ababa Light Rail Transit is new system which has been in operation for the last five years. Understanding the degradation pattern of such system will help in scheduling and controlling maintenance activities, which is a problem to many railway operating entities. Track safety and maintenance effectiveness are improved by clearly understanding future condition of the track. This paper analyses and predicts the track geometry degradation of Addis Ababa Light Rail Transit. Track geometry degradation models developed by different researchers were critically reviewed to determine suitable model for AALRT. Factors which contribute to track geometry degradation were analyzed to determine the relationship between the factors and track degradation. Factors such as Number of Trips, Curve Radius, Speed, Grade, Tonnage and Track Surface were analyzed. All analyzed factors except Track Surface were found to have influence on rate of degradation for curved and straight sections of AALRT. The selected influencing variables and longitudinal leveling changes were used to develop track degradation model. Multiple regression model was developed in SPSS while Artificial Neural Network model (ANN) was developed on MATLAB software. The performances of two models were evaluated for straight and curved sections of North South line. North South line is a double line, model development was performed per each direction (Uplink line and Downlink line) and whole line regardless of direction. Six multiple regression models were developed. For straight sections three models were developed in which Downlink line displayed tremendous performance (R2=98%) compared to Uplink line (R2=85%) and North South line (R2=88%). For curved sections performance of 91% was observed on Uplink line and Downlink line while North South line had performance of 88%. Six ANN models were also developed as a complex model to predict future condition of track. Performance of 97% R-squared was obtained for both curved and straight sections of Uplink line while performance of 96% was observed in straight section and 93% performance was observed in curved sections of Downlink line. North South line display performance of more than 90% for both straight and curved sections of line. Comparison of two models showed that both can predict the longitudinal levelling changes with very low error. Although the ANN model has better performance than Regression model.Item Analysis of Addis Ababa Light Rail Train Wheel Profile Integrity and Onboard Spray Type Wheel Flange Lubrication System Design(Addis Ababa University, 2021-07) Desalegn, Taye; Celestin, Nkundineza (PhD)A wheel flange lubricator sprays lubricant on the wheel flange which comes into contact with the rail at curves, consequently decreasing the wear rate. Electric Multiple Units (EMUs) of Addis Ababa Light Rail Transit (AALRT) are integrated with solid stick wheel flange lubrication mechanism. However, nowadays, AALRT EMUs solid stick lubrication system is not functional because of material cost and lack of availability. This study aims to assess the wear distribution on different wheels of the EMU at different lines and provides a better and effective lubrication system, which is placed onboard of the vehicles. The lubricant of new lubrication system is easily available and cost effective, whereas the mechanism includes curve sensor, oil, pressurized air, nozzle, oil reservoir, oil pump and the lubricating system pump speed which is about 1200RPM was calculated numerically to obtain the oil flow rate. Average tread diameter of North-South line train is 656.2 mm show a total percentage loss of 0.57% when compared to East-West line with an average wheel diameter of 658.3 mm and a percentage loss of 0.25%. The analysis results indicate that North-South line EMU wheel flange wears faster than that of East-West line. It was also found that the trailer car wheels’ thicknesses are worn faster than other two motor bogie wheels. Our designed lubrication system replaces the previous lubrication system (solid stick) and is intended to be operated by priority of fast wearing axle wheels and corresponding vehicles. The oil tanks were estimated to be 0.5 while the flow rate through the spray nozzle is calculated to be approximately 0.326e-3 /s and the standard flow rate at the curve is approximately 0.3e-3m3/s which gives a difference of 0.026e-3 /s with a corresponding error of 7.9%. This is a clear indication that the design process met the international standard for the design of such system. Similarly, the oil flow rates at curves track were seen to be at the acceptable limits.Item Analysis of Aerodynamic Brakes in Mainline of Ethiopia Railway Corporation (ERC)(Addis Ababa University, 2015-03) Hillina, Admasu; Tsegaye, Feleke (Mr.)Aerodynamic brakes are used as auxiliary braking system in rolling stock. The aerodynamic brake is defined as a stiffened plate subjected to lateral pressure load considering buckling behavior. This research is prepared for the computational fluid analysis (CFD) of aerodynamic braking plate by using Finite Element Method to improve arrangement of braking plate and analyze for Ethiopian National Train (ENT).Through the research the current speed of ENT IS taken(120km/hr) and also assumed future speed of 300km/hr is also considered. The analysis is done using the parameters of the rolling stock to be used by Ethiopian Railway Corporation. The assembly of the train body and braking plate area was modeled by using CATIA software. After modeling, analysis for determination of brake force is used by ANSYS Fluent and also the amount of pressure is discussed under four main cases. When the braking plates are positioned at four different angles (450, 600, 750, & 900).The results showed that the drag coefficient increases as the speed increases and also at 120km/hr the aerodynamic effect is less than at 300km/hr. At 120km/hr all the results of pitch moment coefficient were less than one this shows that the train is stable under all four cases. The drag force at an arrangement of 900 was found to be enough to slow down the train at a deceleration of 0.68m/s2 .All the other three cases were invalid because the system cannot achieve the required deceleration. The analysis when the two trains cross each other both equipped with aerodynamic braking plate was also analyzed. The result achieved was the maximum pressure during crossing was 2.39kpa.this pressure can be easily resisted by the window glass which can resist 8.3kpa pressure. Therefore the system can work without any pressure effect. The results were discussed by displaying the drag coefficient, the lift coefficient, residuals, moment coefficient and pressureItem Analysis of Differential Settlement of Ballasted Railway Track(Addis Ababa University, 2019-07) Nahusenay, Tesgera; Henok, Fikre (PhD)A railway track will deteriorate when exposed to repeated traffic loadings and with it, track alignment changes and track level settlements will also occur on selected areas of a given stretch. This irregularity created due to repetitive use of the system will shorten the intended service life of the track components unless elements that induce deteriorating effects are studied and monitored well. This research focuses on the study of the root causes of uneven settlements of a ballasted railway track system. The study will investigate into identifying what the frequent causes of differential settlement of ballasted railway tracks are. After assessing the basis of this condition, the impact uneven settlement has on the track system will be surveyed with the help of extensive literature review of studies made about similar cases. Alongside this, in order to fully understand and quantify the settlement behavior of the track system, the proposed approach will be to model the existing ground condition of the track system (using track component material properties) using a computer programmed tool named ABACUS and analyze the anticipated settlement behavior of a selected sampled section under investigation. The findings of this study will be the derivation of profile characteristics of sample potentially differentially settling section in the Addis Ababa Railway Transit line and thus show that specific area of the transit line need frequent inspection due to its unique behavior.Item Analysis of Effect of Train Overload on Disc Brake of AALRT(Addis Ababa University, 2015-05) Solomon, Kebebew; Tsegaye, Feleke (Mr.)Changes in the train dynamics characteristics such as train weight will affect the train’s braking performance and its ability to stop safely in braking situation. This paper studies about the disc temperature and von misses stress of train over loading used in AALRT. A transient thermal analysis has been carried out to investigate the temperature variation across the disc using ANSYS 14.5. Further structural analysis is also carried out by coupling with thermal analysis. A more realistic braking disc model for AALRT under various over load percentages, road grade level and maximum travel speed of 70km/h is analyzed. The model of disc brake is done by CATIA software and then simulation was followed using ANSYS 14.5 workbench. Results from this research showed that the temperature and stress on disc brake during service brake at downhill train position and unacceptable load condition has increased by 37.08 o c and 56 Mpa from acceptable load and the same train position. When a repetitive braking is applied the temperature and von misses stress during train overload has increased by 37.07 o c and 56 Mpa respectively. Similarly, when the emergency brake is applied during normal and unacceptable load condition, the temperature and stress on the disc has increased by 41.4 o c and 51 Mpa in time of downhill track position. In general, overloading the train has the effect of increasing the temperature and stress induced in to the disc brake rotor during brakingItem Analysis of Effect of Train Overload on Energy Consumption of AALRT(Addis Ababa University, 2016-06) Mekdes, Mekonnen; Tollosa, Deberie (Mr.)especially for the traction in its daily operation. To implement energy saving programs and to study economical operation strategies, an energy estimated model is required. The models can be further extended to develop models and simulation for estimating power demand of train operation and minimizing energy consumption through different driving strategies. In order to make analysis for train energy consumption and regenerative energy, this thesis work focuses only Ayat to Torhiloch (East Wast) line of Addis Ababa Light Rail transit (AALRT). The main targets of this research work is to analyze the effects of train overloading in energy consumption of AALRT by comparing with different load conditions such as normal and maximum load. During peak hour the number of passengers are high, overloading affects energy consumption because it takes more energy to accelerate the train. Mathematical modeling and simulation based analysis are presented to analyze the effects of overloading on train energy consumption. The models are formulated using train dynamics, train tractive effort and driving resistance which includes aerodynamic, gradient and rolling resistance. The methodology to evaluate energy consumption is based on power and time. In this research work Matlab/Simulink software is developed to analyze train energy consumption and regenerative energy. The method that used to create the simulation of energy analysis at different track position such as level, uphill and downhill position. Finally, the Simulink result shows that, there is 11.05 % additional energy consumption is used during overloading when it is compared to normal train loading, 6.22 % used when it is compared to maximum train loading condition. The result shows that during overloading the train needs high amount of energy consumption to accelerate.