See Also...409 406 ISOM Index Vegetation index previous next
revision 05/00
408 Forest: difficult to run
An area with dense trees or thicket (low visibility) which reduce running to ca. 20 - 60% of normal speed.
Colour: green 60% (60 lines/cm).
As ISOM 2000 but percentage tone changed from 50 to 60% and runnability band changed from 10-50% to 20-60%.
Defined as area symbol 408.0, and can be drawn with any drawing tool.
Care is needed at joins, overlap only where it is safe (usually if it is the same colour and always if it is the same symbol). If you need to share a common boundary with another symbol, draw along the edge with the control key to follow it exactly.
The runnability depends on the nature of the forest (density of trees/brushwood and undergrowth- bracken, brambles, nettles, etc.) but does not take account of marshes, stony ground etc. which are shown by separate symbols. There is a runnability topic.
See minimum dimensions but specifically -
- Smallest area enclosed by a dotted line: 1.5mm (diameter) with 5 dots.
- Smallest area of colour green dot screen: 1.0mm˛.
The ISOM lays down the permissible combination of screens.
Forest (difficult to run) is allowed with broken ground, stony ground, marsh, and indistinct marsh,
but not with uncrossable marsh, open land, open land with scattered trees, rough open land, rough open land with scattered trees, forest: slow running, undergrowth: slow running, undergrowth: difficult to run, or vegetation: very difficult to run.
Thicket: an area of forest where the tree cover or undergrowth is so dense that it is difficult to pass.
Felled area: an area of felled or fallen trees.
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