Standards Development

Scope

This specification addresses the limitations of conventional estimation methodologies that rely on fuelbased data or aggregated annual vehicle mileage statistics. Existing approaches do not adequately reflect actual traffic conditions, and the time lag inherent in the inventory development process makes it difficult to determine, in a timely manner, whether greenhouse gas (GHG) reduction targets have been achieved.

To overcome these limitations, this specification is intended to provide improved accuracy and timeliness in the estimation of greenhouse gas emissions from the road transport sector by utilizing activity data collected from nomadic devices and traffic information data collected from Intelligent Transport Systems (ITS) detection devices.

ISO 23795-4 specifies a methodology for estimating greenhouse gas emissions from the road transport sector through the calculation of Vehicle Kilometres Travelled (VKT). The methodology utilizes data collected from nomadic devices, including density, speed, traffic volume, sample volume, and location information, together with measured values obtained from traffic detection devices, and applies expansion techniques to derive population-level traffic activity data.

This specification defines a VKT estimation method based on measured and estimated data for individual road sections. It also specifies a VKT calculation method, in accordance with the Tier 3 (T3) approach, in which the minimum unit of analysis is defined as the link between intersections, and VKT is derived using point-based average traffic volume by vehicle type and fuel type together with section length.

Purpose

Under the Paris Agreement, Parties have committed to the implementation of Nationally Determined Contributions (NDC). While national strategies for GHG reduction are being established globally, detailed technical methodologies and data-driven systems for estimating and managing these emissions remain largely insufficient.

The transport sector accounts for approximately 13.7% of global carbon emissions, with 89.1% originating from road transport. As of 2024, GHG emissions in this sector have shown the most rapid long-term growth, increasing by 79% since 1990. This trend underscores the urgent need for a systematic, data-driven management framework.

Accordingly, this document addresses the limitations of existing fuel-based or annually aggregated VKT estimation approaches—specifically their inability to reflect actual traffic activity and the time lags inherent in inventory preparation. To overcome these challenges, this document aims to enhance the accuracy and timeliness of GHG emission estimation in the road transport sector by utilizing activity data collected via various Nomadic Devices (ND).