Resources

Purpose

This purpose of this  note is to make you aware that Waka Kotahi NZ Transport Agency is changing its future procurement to move from hot cut-back bitumen to the use of bitumen emulsion in its highway sealing operations.  This will not be immediate but will be phased in during the next few years.  You will find the dates below.

General information

The majority of chip seal surfacing in New Zealand is currently constructed using hot cut-back bitumen. Chip seal surfacing using bitumen emulsion offers safety and environmental benefits compared to cut-back bitumen. Waka Kotahi has a focus on the resultant bitumen layer and currently allows either of the delivery systems to be used. As emulsions are more expensive than cut-back bitumen, they are often disadvantaged in a competitive market.  However, the health and safety benefits are well proven, as are the better environmental outcomes.

Move to bitumen emulsion 

Waka Kotahi recognises the advantages of bitumen emulsion for New Zealand and is committed to supporting the change needed to allow for wider adoption. To enable this change to occur Waka Kotahi will transition to mandating the use of bitumen emulsions for all state highway works.  Waka Kotahi will mandate the transition only for state highways, but will encourage and support other road controlling authorities who currently do not use emulsions to transition with us.

Implementation

The move from cut-back bitumen to bitumen emulsion will be supported through the phases indicated below:

• For all existing contracts Waka Kotahi will continue to support the use of bitumen emulsions
• For all new contracts issued prior to 30 June 2024 Waka Kotahi will assess the opportunity to mandate bitumen emulsion on a case by case basis.
• For all new contracts issued after 1 July 2024 Waka Kotahi will mandate the use of bitumen emulsion for sealing operations.

These changes will be applied to all state highway works including maintenance.  Waka Kotahi will provide support to local authorities to adopt bitumen emulsions through this process.

Next steps

To support industry during the transition period Waka Kotahi will undertake to:

• develop and publish an emulsion specification to assist with the specifying and purchasing of bitumen emulsion
• develop, in collaboration with industry, training and safety procedures to support the use of bitumen emulsion
• encourage and support Local Authorities to adopt bitumen emulsions for their operations.

Publication details

Author: Waka Kotahi NZ Transport Agency
Published: May 2021
Version: 1
Location: https://www.nzta.govt.nz/roads-and-rail/highways-information-portal/technical-advice-note/

Further information

If you have any questions or feedback, please contact the Lead Advisor Pavements at pavements@nzta.govt.nz

[signed]

David Darwin - Chair, Ratification Group

Vanessa Browne - Delegated Approver