Most of the raw data comes from Stats NZ. We use that to generate the indexes every quarter. The exception is the bitumen cost adjustment series, which we calculate and publish monthly.
Stats NZ open data - Infoshare (stats.govt.nz)
The zip folder contains four items.
Latest values for bitumen cost adjustment series.Latest index values for infrastructure cost indexes - ORIGINAL 1991 series.Latest values for infrastructure cost indexes NEW series.Latest cost index values for public transport.
You can download the data by clicking on the 'Download' button at the top of this page.
You can find out more, including reading the procurement manual, on the procurement tools page on nzta.govt.nz. See the links below.
Procurement tools page (nzta.govt.nz)Contract price adjustment for cost fluctuation: infrastructure contracts [PDF, 1.1 MB]
Note: file name is 'instructions-for-bitumen-volumetric-approach'.
Adjuster tool (adjuster.nz)Cost indices for public transport [PDF, 388 KB]Bus and ferry cost indexation tool (nzta.govt.nz)
Data reuse caveats: As per licence.
Data quality statement: Stats NZ releases the source data that Waka Kotahi uses to generate these indexes. The indexes are fixed every quarter, except for the bitumen series (fixed monthly).
Data quality caveats: See data quality statement.
Photo: screenshot from procurement manual cover, showing roadworks. Credit: Waka Kotahi NZ Transport Agency.