Preface: This is the fifth edition of CSA S6.1, Commentary on CSA S6:19, Canadian Highway Bridge Design Code. It supersedes the previous editions, published in 2014, 2006, 2000, and 1990. Throughout this Commentary, CSA S6:19 is referred to as the "Code". Other Codes are always identified in a manner that allows them to be readily distinguished from the Code. The purpose of this Commentary is to provide background on the design provisions of the Code and thereby to help designers deal with issues not explicitly addressed in the Code. Each section and clause in this Commentary bears the number of its corresponding section or clause in the Code, with the addition of the prefix "C". For example, Section C1 provides commentary on Section 1 of the Code, and within Section C1, Clause C1.1.1 provides commentary on Clause 1.1.1 of the Code. The same approach is used in the numbering of annexes. Tables and figures are numbered sequentially (for example, the first table in Section C3 is Table C3.1, which is followed by Table C3.2, etc.). However, they do not correspond to the tables and figures bearing the same numbers (minus the "C") in the Code. The Code contains many clauses dealing with "approval" by owner or regulatory authority (see the definitions in Clause 1.3.2 of the Code). Where possible, this Commentary provides guidance for owners or regulatory authorities consulting such clauses. -------------------------------------------------------------------------------------------------------------------------------- Section C1 - General C1.1 Scope C1.1.1 Scope of Code The OHBDC (MTO 1991) was written for application within Ontario. CAN/CSA-S6-88 was generated with interprovincial co-operation for use in the other provinces of Canada and was largely derived from the preceding OHBDC edition. The provinces and CSA then agreed that the successor edition to both codes would be the Code, published by CSA. The scope of the Code is a little broader than that of the third and last edition of the OHBDC (MTO 1991). Long span bridges and movable bridges are included. Over the years, new sections have been added to the Code, namely Section 16 on Fibre-reinforced Structures and Section 17 on Aluminum Structures. The 2019 edition of the Code includes a new annex in Section 8 on fibre-reinforced concrete. In addition to incorporating newer technology, more emphasis is placed on criteria related to seismic design, durability, sustainability, and access for inspection and maintenance. Also new in the 2019 edition of the Code are limited climate change requirements and guidance provided for the design of structures in impacted regions of Canada. The scope statement lists types of structures to which the Code is not intended to apply. The list is not exhaustive. The application of the Code to the types of structures listed is not precluded where the owner of the structure has designated all or part of the Code as being applicable. See preview for scope of each section