Development of New Improved Geometry Of Switch in Ethiopian Railroad Track (EMAMY Switch)
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Date
2017-10-30
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Addis Ababa University
Abstract
A railroad switch is a device, which enable a rail vehicle to change from one track to another track by
means of pair of linked tapering rails known as points or point blades that are lying between the diverging
outer rails (the stock rails). These points can be moved laterally in to one of the two positions to direct a
train coming from the point blades toward the straight path or the diverging path.
A rail track switching system has been designed to control railway track and such controlling is
exercised through the use of various track circuits which detect the presence of trains on a particular track,
signals within a given area from a single point and central room which monitors the train’s safety. But,
something electric failure or signals not gives exact location, the switch machine doesn’t detect the train
is there, due to this, the switch doesn’t shift its position, this makes, train in danger or no ways to change
direction. Therefore, this research will solve such grate problem by development of new improved
geometry of switch with lock rail, due to this improvement, the structural geometry become very easy,
simple and applicable in anywhere in railroad line.
Referring to the design analysis of improved switch rail from the geometry and ANSYS result and
Referring to the design analysis of existing switch rail from literature review, for the same structural
support stiffness, existing railway switch shows 2.248 mm at section A-A, 2.158 mm at section B-B and
1.398 mm at section C-C vertical deflection, which are relatively smaller than 3.14mm ISW rail
deformation. Hence, the results are within the range of AREMA maximum vertical rail deflection limit
which is 6.35mm.This mean that, both rail sections are sufficient enough for the maximum design load.
According to the shear parameter, the existing railway switch, for the same radius of wheel and for the
same steel structure with equal sleeper spacing shows 149.09 MPa Maximum shears which is greater than
140MPa allowable maximum shear stress. For this reason, the sections are less resistance for high force
and vibration than the ISW rail one, which is 8.8 MPa. In case of stress, the current switch shows
137.826MPa at section A-A, 69.468 at section B-B and 45.603 at section c-c maximum stress which is
very high comparing to the improved one, switch is 16.277 MPa, this is due to section modulus variation.
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Keywords
Existing railway switch, section design, geometry design, improved switch, guard-wing rail, 3D ANSIS ISW model, deformation, Equivalent stresses, maximum shear stresses