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Traffic monitoring for state highways (SM052)

Published: | Category: State highway operations , Manuals | Audience: Road traffic engineers & consultants

This manual describes the current methodology for traffic monitoring, the technology involved, conventions, survey guidelines, calculations and an overview of the software system.


Publication details

  • Author:
  • Published: July 2004
  • Version: Version 1.2
  • Also known as: SM052

Tools and resources

Open data portal

Our open data portal has a number of traffic count-related data sets, from quarter-hourly historic datasets to daily-updated datasets (API or CSV) and more.

Traffic-related open data on our open data portal(external link)

State highway traffic monitoring map

Our interactive map displays traffic count sites and estimated traffic volumes for state highways.

State highway traffic monitoring map(external link)

Vehicle classification relationships

For sites that use dual loops classification is by length. Vehicles with a length of less than 5.5m are classed as light vehicles. Vehicles over 11m long are classed as heavy vehicles. Vehicles between 5.5 and 11m are split 50:50 into light and heavy.

The NZTA Vehicle Classification Relationships diagram below shows the length classification (typically dual loops) and axle classification (typically pneumatic tube counts), and how these map to the Monetised benefits and costs manual, table A37, page 254.

heirarchy diagram of vehicle classification relationships

How vehicles in the daily-updated TMS traffic count API and CSV in the Waka Kotahi open data portal are classified.

Monetised benefits and costs manual [PDF, 10 MB]

For the full TMS classification schema see Appendix A of the traffic counting manual vehicle classification scheme (NZTA 2011), below.

Traffic monitoring for state highways: user manual [PDF, 465 KB]