Track Design Handbook for Light Rail Transit, Second Edition (2012) / Chapter Skim
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Pages 576-587
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From page 576... ...
11-i Chapter 11 -- Transit Traction Power Table of Contents 11.1 GENERAL 11-1 11.1.1 Traction Power System Components 11-1 11.1.2 Traction Power/Track Interfaces 11-1 11.2 TRACTION POWER SUBSTATIONS 11-2 11.3 WAYSIDE DISTRIBUTION SYSTEM 11-3 11.4 CATENARY SYSTEMS 11-4 11.4.1 Introduction 11-4 11.4.2 Catenary Alternatives 11-4 11.5 CATENARY DESIGN 11-5 11.5.1 Introduction 11-5 11.5.2 Conceptual Stage 11-6 11.5.3 Application of the Catenary System to the Track Layout 11-6 11.5.3.1 Track Centers 11-7 11.5.3.2 Horizontal Curves 11-7 11.5.3.3 Vertical Profile 11-7 11.5.3.4 Vertical Curves 11-7 11.5.3.5 Interlockings 11-8 11.5.3.6 Track Adjacent to Stations 11-8 11.6 TRACTION POWER RETURN SYSTEM 11-8 11.6.1 Territory with Two-Rail Track Circuits for Signaling 11-8 11.6.2 Territory with Single-Rail Track Circuits for Signaling 11-9 11.6.3 Territory without Signaling Track Circuits 11-9 11.6.4 Rail Conductivity 11-9 11.7 CORROSION CONTROL MEASURES 11-9 11.8 MAINTENANCE FACILITY YARD AND SHOP BUILDING 11-10
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From page 577... ...
11-1 CHAPTER 11 -- TRANSIT TRACTION POWER 11.1 GENERAL Light rail systems, as defined in Chapter 1, use electrical power from overhead wires to provide traction power to the light rail vehicles. The rails, sometimes in conjunction with supplemental negative return cables, act as the return conductor to the negative terminal of the rectifiers.
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From page 578... ...
Track Design Handbook for Light Rail Transit, Second Edition 11-2 11.2 TRACTION POWER SUBSTATIONS Traction power substations take commercial alternating current power from the local utility company and convert it into the direct current required by the LRVs. The optimal locations for the traction power substations are determined using a computer model that simulates proposed LRT operations along an accurate geometrical and geographical depiction of the planned route.
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From page 579... ...
Transit Traction Power 11-3 The electrical sectionalization of the distribution system usually takes place at the substation for all travel directions. Placement of a substation at, or near, a crossover is often desired to sectionalize electrical supply for each travel direction and to optimize the operational flexibility of the track system.
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From page 580... ...
Track Design Handbook for Light Rail Transit, Second Edition 11-4 11.4 CATENARY SYSTEMS 11.4.1 Introduction The OCS on a light rail system usually consists of a simple catenary system that incorporates both a messenger cable from which a contact wire (also known as a trolley wire) is suspended.
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From page 581... ...
Transit Traction Power 11-5 trolley wire running surface must be continuous, without any gaps or overlaps. In addition, trolley hardware for pole operation is not normally suited for pantograph operation.
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From page 582... ...
Track Design Handbook for Light Rail Transit, Second Edition 11-6 the locations and design of these components can greatly influence the catenary design and its visual impact on the environment. 11.5.2 Conceptual Stage The catenary engineer's task is to develop a conductor configuration to supply power to the vehicle from a position over the track that will allow good current collection under all adverseweather, operating, and maintenance conditions.
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From page 583... ...
Transit Traction Power 11-7 11.5.3.1 Track Centers The clearance between poles and the track is defined by the system's dynamic clearance envelope, which comprises three elements: the vehicle dynamic envelope, construction and maintenance tolerances, and running clearances. Therefore, if center poles with supporting cantilevers on each side are desired to reduce cost and visual intrusion, then the distance between tracks should allow for this envelope from each track plus at least 12 inches [305 millimeters]
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From page 584... ...
Track Design Handbook for Light Rail Transit, Second Edition 11-8 11.5.3.5 Interlockings The catenary/pantograph interface is a dynamic system. There are certain constraints applied to ensure that the system operates efficiently under all speed and weather conditions.
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From page 585... ...
Transit Traction Power 11-9 11.6.2 Territory with Single-Rail Track Circuits for Signaling Although most track circuits for signaling in new light rail systems are of the two-rail type, singlerail signaling track circuits do exist in older systems. In such systems, one rail is used for traction return and the other is designated the signal rail.
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From page 586... ...
Track Design Handbook for Light Rail Transit, Second Edition 11-10 • The track designer and construction inspector should ensure that ballast is clear of rails so that return currents do not stray into the ground and cause corrosion problems in underground pipes and cables. • Special consideration must be given to selecting the insulation of the rails at grade crossing and embedded track sections to ensure minimum leakage to ground.
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From page 587... ...
Transit Traction Power 11-11 Yard track designers must still consider and account for the many conduit risers necessary to feed the numerous electrical sections in the overhead contact system. Extra coordination in yard areas should take place due to the additional users and electrical connections in the complex track layout.
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