Average number of vehicles per day using an urban road over the course of a year.
Organizations should footnote all assumptions used, including source(s) of data.
This metric is intended to capture the volume of traffic in a particular market or context, expressed as the average number of vehicles using an urban road per day over the course of a year. Organizations may also choose to report average traffic for other periods of time (e.g., traffic per month). Traffic on a road, particularly over time, serves as a proxy for the qualitative contribution of new transportation infrastructure to economic activity.
Providers of GPS traffic data frequently offer traffic counts by side of road, day of week, and time of day.
International Finance Institutions (IFIs) often use this metric as part of transportation analysis. If toll roads are not part of a project, this metric is not a good indicator of impact performance, unless the corresponding transport or transit agency monitors traffic congestion.
June 2022 - IRIS v5.3 Released (current version)
Immaterial change. Minor revision to usage guidance for clarity.
January 2020 - IRIS v5.1 Released
New metric. Average Daily Traffic (OI0659) developed through partnership with HIPSO.
IRIS Metrics Work Better in Sets
To use IRIS metrics—and the resulting data—to understand impact performance, IRIS metrics should be used and analyzed in generally accepted sets and according to well-defined objectives. IRIS+ gives you access to generally accepted Core Metrics Sets aligned to common Impact Themes and Sustainable Development Goals (SDGs).