INTRODUCTION The AREMA Manual for Railway Engineering contains principles@ data@ specifications@ plans and economics pertaining to the engineering@ design and construction of the fixed plant of railways (except signals and communications)@ and allied services and facilities. This material is developed by AREMA technical committees@ is published on the AREMA web site for comments and then is approved for publication in the Manual by the Association's Board of Directors. Designated as Recommended Practice1@ the contents of the Manual are published as a guide to railways in establishing their individual policies and practices relative to the subjects@ activities and facilities covered in the Manual@ with the aim of assisting them to engineer and construct a railway plant which will have inherent qualities of safe and economical operation as well as low maintenance cost. The AREMA Manual is not a maintenance manual per se since the development of standards or criteria for the maintenance of railway roadway@ track and structures has always been considered to be the prerogative of the individual railways based on the nature and characteristics of their plant and operations and the specific characteristics of the geographical region or regions through which they operate. The above statements also apply to the AREMA Portfolio of Trackwork Plans@ which is a companion volume to the AREMA Manual. The plans in the Portfolio relate to the design@ details@ materials and workmanship for frogs@ switches@ crossings and other special trackwork and are prepared and maintained by Committee 5 ?C Track@ in addition to its Manual Chapter. 1 RECOMMENDED PRACTICE ?C A material@ device@ design@ plan@ specification@ principle or practice recommended to the railways for use as required@ either exactly as presented or with such modifications as may be necessary or desirable to meet the needs of individual railways@ but in either event@ with a view to promoting efficiency and economy in the location@ construction@ operation or maintenance of railways. It is not intended to imply that other practices may not be equally acceptable.