Preface
This second edition of Movable Bridges supersedes the first edition published in 1927 under the designation A20.
This Specification is planned to provide definite minimum requirements for the design and manufacture of movable bridges in order to protect both the purchaser and the public. As compared to the previous edition of A20, the arrangement of subject matter has been changed in order to achieve a more comprehensive and unified format. This, it is hoped, will make it easier for reference.
This revision covers for the first time two classes of bridges, those over important channels where operation is frequent, and those over waterways infrequently used and where operation of the bridge is only occasional.
The Committee was fortunate in that a number of its members were involved in the preliminary study, design, building, and tuning up for operation, of the movable bridges over the St. Lawrence Seaway. The experience gained led to numerous improvements in this Specification. The operating performance, over a period of about twenty-five years, of the Seaway's numerous bridges over the Welland Canal was also carefully considered.
The Committee extensively reviewed the latest movable bridge specifications of the American Railway Engineering Association and of the American Association of State Highway Officials and wishes to express its thanks to these organizations for guidance obtained therefrom.
Wherever possible reference has been made to other CSA standards where such cover points .in design, materials, etc., which would otherwise have to be given herein in full.
This Specification was prepared by the Committee on Movable Bridges under the jurisdiction of the Sectional Committee on Steel Construction, and was formally approved by these Committees and the CSA Technical Council.
Scope
1.1
This Specification applies to movable bridges designed for railway, highway, or tramway service, or any combination thereof.
1.2
The requirements for fixed span bridges as given in the latest issues of either CSA Standard Sl, Steel Railway Bridges, or CSA Standard S6, Steel Highway Bridges, shall apply to movable bridges except as herein modified. This includes shop painting.
1.3
Fixed spans which are adjacent to the moving span of movable bridges and some of whose primary components form or support integral and essential parts of the movable bridge, where the design and make-up of such components is governed by conditions of the moving span, shall be considered to be part of the movable bridge structure.
