Terrain Categories and Terrain Parameters

According to EN 1991-1-4, Table 4.1.

Terrain categoryDescription
00Sea or coastal area exposed to the open sea.
1ILakes or flat and horizontal area with negligible vegetation and without obstacles.
2IIArea with low vegetation such as grass and isolated obstacles (trees, buildings) with separations of at least 20 obstacle heights.
3IIIArea with regular cover of vegetation or buildings or with isolated obstacles with separations of maximum 20 obstacle heights (such as villages, suburban terrain, permanent forest).
4IVArea in which at least 15 % of the surface is covered with buildings and their average height exceeds 15 m.