Title: Concrete Ties for U.S. Railroads -An Update

Author(s): A. N. Hanna

Publication: Symposium Paper

Volume: 93

Issue:

Appears on pages(s): 267-286

Keywords: ballast; fasteners; performance; prestressed concrete; production methods; railroad ties; specifications; tests

DOI: 10.14359/6306

Date: 9/1/1986

Abstract:
The prestressed monoblock concrete tie is today the most widely used concrete tie in the United States. Three rail-roads In the United States are considered regular users of pre-tensioned concrete ties. The ties have been manufactured by the long-line or individual form method. High strength concrete and tendons have always been used for the production of concrete ties. Quality assurance programs that address material proper-ties, production operations and tolerances, and dimensions and strength of produced ties are implemented to assure consistency in quality and performance. In developing tie designs, permis-sible stresses specified in applicable codes and standards should not be exceeded. Tie length should be sufficient to assure development of prestressing force by bond within the distance between the rail seat and tie end. Tie bottom width should be suff1client to produce a ballast pressure within permissible limits. For good performance and long life, tie design should be based on the prevention of cracks under normal service condi-tions after consideration of concrete fatigue. Performance of concrete ties in track is influenced greatly by the functioning of both the rail fastening system and the ballast section. There-fore, rails, ties, fasteners, and ballast should be considered integral parts of the track structure. The ability of ties and fasteners to withstand anticipated dynamic and static loads, to control rail movements, and to provide electrical insulation is evaluated by laboratory tests. The growing interest in use of concrete ties by U.S. railroads is justified by the consistency in product quality, apparent low annual cost, and superior performance.