The purpose of this thesis is the improvement of Iran�s railways network curves. This process is based on theoretical and scientific assumptions that include the study of technical and experimental reports prepared by some other countries. In this regard a FORTRAN code, which represents the characteristics of simple and clothoidic curves, is written and this code can be used for other curves as well. Also in this document my goal is to propose some other ways �if there is any- to improve the curves result to increase the train speed and decrease of the railways� erosion and cost of railways handling. This study will focus on the relationship between the different train speed and the curves. To clear the subject and suitable curve design, the knowledge of applied forces and the nature of the wheel and rail contact are two important factors that will briefly be addressed at the end of this document. The other cases that are discussed thoroughly in this text are the curves variety and their relationships, and also the superelevation phenomena. Considering to the sources limitation it should be emphasized that the majority of the equations are justified and proposed by the author. This thesis is presented in eight chapters. First chapter is about the present situation of the Iran railway including railway paths, operation starting date, possible maximum speed, longitudinal gradient and other crucial characteristics of the railways, introduction of the other transportations and comparing them to the train network. Second chapter is rail forces: 1) Vertical rail forces 2) Horizontal, transverse to the track (Quasi-static loads and Dynamic loads) 3) Horizontal, parallel on the track Chapter three is Resistance elements: 1) Train resistance: Resistance varying with the load (Rolling resistance, journal resistance, Track resistance, and Flange resistance.) and Resistance varying with the velocity (Air resistance). 2) Route resistance: Grade resistance and Curve resistance. 3) Movement resistance: Acceleration resistance and Deceleration resistance. 4) Other resistive forces: Internal resistance, Wind resistance, Tunnel resistance, Low temp resistance, Switch resistance, and Starting resistance. Devoted to the suitable curve design based on relative gradient so that based on this gradient the train can be used with an optimum pulling power. The result of this design will decrease the curve resistance, which in turn increases the train speed. Chapter four includes the wheel and rail erosion mechanism, centrifugal force and the cost of increasing curves erosion. Chapter five presents the abbreviations and then effective elements on speed in curves are pointed out. These elements will be divided to circular curve and connectional curve by itself. In circular curve, Transversal Gradient (TG) or super elevation and its limit, effect of different acceleration on the passengers, lack of TG, extra TG and the equilibrium speed will be explored. In the connectional curve section, connection length between compound curves, curves without connection, TG change amount, TG change in direction of line; curve radius. Finally the super elevation ramp is discussed. Chapter six focuses on the advantages of direct over curvature path and its uses, path and speed classification and their effect on the path design, simple curve; the minimum radius and the maximum train speed, curve parts, simple curve improvement and length optimization. Chapter seven gives insights about the need on connectional curve (CC), practical and technological conditions of CC, curvature and lateral acceleration, CC length, CC varieties, third degree parabola, parabola curve dismantlement, parabola maximum radius, forth degree parabola and its equation, clothoid curve, its equation and dismantlement, horizontal curve selection and design, minimum length of transition and the other points related to horizontal curves design. Chapter eight verifies curves durability and resistance against implied forces; curves keeping and handling, correction and adjustment, curve improvement, solution for connection length addition, disconnected rail in curves and change line in curves. At the end of the last chapter there are some appendices; the first is a few problems with solution about curve and super elevation, the second is Iran railway standards and the third is a FORTRAN code for calculating circular and clothoid curve. Conclusion and propositions: � In Iran, most of the curves of transit railway are third degree parabola that is not suitable for high-speed train. These curves can be replaced by forth degree parabola and clothoid curves but because of drastic acceleration change in wheels, the use of the last curves are limited. � Transit curve length should be calculated somehow that during passing the curve the train has a fast and smooth movement without shock. This will guaranty passenger security and welfare. In the mountainous regions the increase of the transit length curve may be difficult and costly. In such cases we may increase the middle curve radius and� � In superelevation case we should be careful to calculate superelevation related to the new speeds and the number of new trains. On the improved path, trains with low speed will have problem related to superelevation. To calculate minimum authorized superelevation, the passenger security and welfare parameter as transit curve length, should be considered. Also related to superelevation, stability and derailment should be considered when the train passes the curve especially in speeding. Only in such cases the train should be loaded to an authorized height or the wagons that their gravity centers are closer to the ground must be used and�. � The increase of middle curve radius has many effects in the increase of train speed. These changes are; decrease of curve resistance, increase of curve radius results to the increase of train security movement and passenger welfare and � � Lateral curves should have at least thirty meters straight path and preferably V/2, (V is in kilometer) unless� |