Question:
Why are the tolerance zones between the zone borders 5 km wide on the online snow load map of Austria?
Answer:
With National Annex ÖNORM B 1991‑1‑3:2018‑12, Austria has textually redrafted the width of tolerance zones.
[1] In the third paragraph under "Annex B", the standard states accordingly that within 2.5 km on both sides of the zone boundary, the characteristic value s-k is the average of the affected zones. In the area of Vienna, we can assume 250 m per side. This results in the tolerance zone width of 2 x 2.5 km = 5 km in the country and 2 x 250 m = 500 m in Vienna.
→ See Snow Load Map of Austria
This regulation was applied with the update of ÖNORM B 1991‑1‑3: 2018̩12 on our website Snow Load, Wind Speed, and Seismic Load Maps.