Schedule and Count
When should short duration counts be conducted? Research suggests that the best time to count is when bicycle and pedestrian traffic volumes are highest.1 This should reduce error in estimating Annual Average Daily Bicyclists/Pedestrians (AADBP). For North American climates with severe to moderate winters, this time period is usually May through October as illustrated in the graph of annual average daily bicyclist (AADB) estimation error in Colorado below. This is likely to apply to typical Midwestern North American climates.
Because many programs have not included permanent bicycle and pedestrian counts, short count programs often choose to count on the same day of the year every year. For example, the National Bicycle and Pedestrian Documentation Project recommends counting in mid-September every year. However, if a robust set of permanent counters are in place with which to compute factors, it may not be necessary to count the same location every year. For example, a given site might only be counted once every three years, as is common in motor vehicle short duration count programs. This can greatly increase the number of sites that can be measured.
4.5.4 MONTHS/SEASONS OF YEAR FOR DATA COLLECTION
The specific months/seasons of the year for short-duration counts should be chosen to represent average or typical use levels, which can be readily determined from permanent continuous counters (thereby underscoring the importance of these automatic continuous counters). In most climates in the U.S., the spring and fall months are considered the most representative of annual average non-motorized traffic levels (e.g., the NBPD projects recommends mid-May and mid-September).
1Nordback, K., W. Marshall, et al. (2013). Estimating Annual Average Daily Bicyclists: Error and Accuracy. 92nd Annual Meeting of the Transportation Research Board. Washington, D.C., National Academies.