Before we begin, it’s important to note that every correction factor needs a Count Validation first! Here you will learn everything about the count validation process.
Why apply a correction factor?
Once the counter is confirmed to be performing as designed, collecting additional manual counts can be used to build site specific correction factors. Correction factors are developed to adjust raw counter counts to more accurately represent the ground truth. The exact accuracy of a counter will vary based on the particulars of the installation, field conditions, traffic patterns, and other site-specific variables.
Potential sources of counter inaccuracy
Occlusion (Masking)
When two or more people cross the counter’s detection zone at the same time, the nearest person can mask others and prevent them from being counted. This masking effect is most common for side-mounted systems (such as the PYRO) and at sites with high volumes, wide paths or locations where there is frequent grouping of users.
Counter Bypassing
While a counter may accurately count the users that pass through its detection zone, it may not be counting all pedestrians and cyclists if bypassing its detection zone is possible. Applying a correction factor will correct for these “blind spots” at the counting site.
Best Practices for Correction Factors
Applying Constant Correction Factor in Eco-Visio
Reminder: Correction Factors are being applied on the Flow level.
Go to → Counting Site Details → Counting Flows tab → Click on 3 dots next to the flow Identifier → Check the correction factor box in the middle on the top.
The factor can be applied as follows:
1.1 = +10% ; 1.2 = +20%, etc. / 0.9 = -10% ; 0.8 = -20% etc.
Application notes:
- It is important to note that the Constant Correction Factor will be applied to the entire dataset and it is currently impossible to only apply it for a shorter period in Eco-Visio
- The workaround for the above is exporting raw data from a site in Excel format, applying Correction Factor using Excel formulas to a short period of time, saving the document, and reuploading it back back to the EV site.
- If you remove the correction factor and apply a new one, the most recent will override the initial factor.