Use of short-term counts and surveys
The main concern with short-term counts is that they do not accurately capture variations in walking over time (i.e. time of the day, day of the week, season, as well as weather). If you count on a sunny day, you may see larger numbers than on a rainy day. Since HEAT assumes that the entered data reflect long-term average levels of walking, data from short-term counts will distort the results.
This issue will mainly affect single facility evaluations (e.g. a footpath, or a bridge) where counts are conducted on the facility itself, or community-wide evaluations that are based on surveys conducted only during a certain time of the year.
Not affected by this issue are assessments based on large surveys, which are conducted on a rolling basis (e.g. national household surveys), or automated continuous counts.
Short term counts may also be adjusted for temporal variation, to better reflect long term levels of walking. An example for how this can be done is provided by the US National Bicycle and Pedestrian Documentation Project
Use of data from few locations
Use of trip or count data
In HEAT, trip or count data needs to be combined with an estimate for average trip length, to calculate the volume of walking. An example is counts conducted on a bridge, where it remains unknown how far people walk beyond the bridge.
Average trip distance estimates may be derived from user surveys on a specific facility, or from travel surveys.
Use of pedometer data
If assessments are based on pedometer data, it should be ensured that the number of steps used is predominantly composed of intentional brisk walking. Some pedometers have a function that excludes steps that are not deliberate walking. Another approach could be to include only intentional walking steps at a rate of about 100 steps per minute or to make an assumption of the proportion of total steps falling into this category.