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#22-04 Release of Bridge manual 3rd edition amendment 4

Published: | Category: Technical advice note | Audiences: Road controlling authorities, Road traffic engineers & consultants, Roading contractors

This technical advice note is to advise that amendment 4 to the Waka Kotahi NZ Transport Agency Bridge manual 3rd edition and amendment 1 to the Bridge manual commentary, both published in May 2022, are available on the Waka Kotahi website for download.

Publication details


This technical advice note is to advise that amendment 4 to the Waka Kotahi NZ Transport Agency Bridge manual 3rd edition and amendment 1 to the Bridge manual commentary, both published in May 2022, are available on the Waka Kotahi website for download.

General information

The Bridge manual sets out the criteria for the design and evaluation of bridges, culverts, stock underpasses and subways and the design of earthworks and retaining structures.

New or replacement bridges proposed for funding from the National Land Transport Fund (NLTF) must conform to the requirements of the Waka Kotahi Bridge manual.

Intent of the update

Amendments to the Bridge manual are required and made on a continuing basis in response to feedback and new practices from practitioners and other standard developing agencies, and relevant research from New Zealand and overseas.

It has been evident for some time that the live load model for vehicles, HN-HO-72, has reached its limits in terms of providing for future growth. The model also has specific scenarios where the loading is known to be unconservative. A project has been underway for some time to replace HN-HO-72, which has been in use for 50 years, and other elements of bridge loading. This amendment 4 includes the first of two phases to update live loading in the Bridge manual and is the building block to a proposed future amendment that will introduce the replacement to HN-HO-72.

Communication plan

The target audience for the Bridge manual is generally experts involved in the design, specification, construction and maintenance of highway structures. Advice of these changes will be promulgated by:

  • this note advising the release of these new documents
  • direct access via the website and intranet
  • appropriate industry presentations.

Consultation with key industry experts and local authorities has already been undertaken during development of these documents.


Amendment 4 to the Waka Kotahi Bridge manual 3rd edition may be implemented immediately. For existing highway projects, confirmation should be sought from Waka Kotahi, or the relevant road controlling authority for non-state highway schemes, whether this amendment may be used, or designs should still be undertaken in accordance with earlier versions of the Bridge manual.

The amended Bridge manual and Bridge manual commentary are available on the Waka Kotahi website at for download.

Review of previous technical advice

The status of the following current technical advice notes (TANs) affected by this amendment to the Bridge manual (BM3.4) should be noted:

TAN #17-09 Verification testing of steel materials

Purpose: To define a consistent mandatory approach for the verification of steel materials on Waka Kotahi projects.
Status: Still current as referenced in BM3.4 clause 4.3.7. Will be superseded by a standard specification for steel once published.

TAN #19-06 Bridge manual, third edition, amendment 3

Purpose: Advisory notice of Bridge manual update publication and notice of affected TANs status.
Status: Superseded. Withdrawn.

TAN#19-07 Bridge manual – mechanical reinforcement couplers and anchors – interim advice (July 2019)

Purpose: Outlines interim requirements for the use of mechanical reinforcement couplers and anchors, subsequent to the publication of the Bridge manual 3rd edition amendment 3.
Status: The amended BM3.4 clause 4.2.1(f) replaces the requirements of this TAN.

However, the requirements of this TAN shall remain in place for a period of six months (ie until the end of October 2022) as alternative means of compliance.

Note that for projects tendered prior to the publication of BM3.4, the requirements for couplers and anchors that applied when the project was tendered shall apply unless agreed otherwise with the Transport Agency’s Lead Advisor Structures, whereupon the requirements of BM3.4 shall apply instead.

TAN#20-15 Use of timber poles for ground improvement

Purpose: Places limits on the use of timber poles for ground improvement.
Status: Details incorporated in BM3.4. Withdrawn.

TAN#21-12 Design and procurement of geosynthetics for soil reinforcement

Purpose: Confirms and refines the approval process and design requirements for geosynthetics used on Waka Kotahi projects.
Status: Supplements BM3.4 information. TAN remains current as an advisory notice.

TAN#21-13 Seismic design of the facing-to-reinforcing connections for mechanically stabilised earth structures

Purpose: Sets out design requirements for geosynthetic reinforcement-to-facing connections on mechanically stabilised earth (MSE) structures during seismic events.
Status: Details incorporated in BM3.4. Withdrawn.

TAN#22-02 Interim technical standards for the design of timber bridges

Purpose: Guidance on the technical standards that can be used for the design of a broad spectrum of timber bridges, including glue-laminated bridges.
Status: Remains current. Will be cancelled by the next amendment to the Bridge manual.

Guidance on use

Extensive amendments have been made to the live loading and evaluation process for determining the capacity of existing bridges. The loads are more complicated than previously used but will far better replicate heavy vehicle traffic on the highway network. It is possible that there will be a number of bridges on the network where the capacity is found to be less than currently known and these findings will need to be managed. It is not intended that large numbers of bridges will suddenly need new posted weight limits. TAN guidance or direct communication with those undertaking evaluations and some adjustments to load factors may be needed in the future.

Document review

Review of the Bridge manual is a continuous process. Feedback from users is welcomed.

Publication details

Publication: Bridge Manual (SP/M/022)
Author: Waka Kotahi NZ Transport Agency
Published: May 2013
Reference: ISBN 978-0-478-37162-8 (print) or ISBN 978-0-478-37161-1 (online)
Version: 3rd edition, amendment 4, May 2022

Publication: Bridge Manual commentary – 196 pages [PDF, 3 MB]
Author: Waka Kotahi NZ Transport Agency
Published: October 2018
Reference: ISBN 978-1-98-851240-2 (online)
Version: 1st edition, amendment 1, May 2022

Further information

If you have any questions or feedback, please contact the Engineering Standards structures team at



Greg Haldane
Chair, Ratification Group

Vanessa Browne
Delegated Approver