Importing a barrier file can be useful for stopping a fire along pre-determined routes such as stream channels or roads. This barrier is impermeable to a surface or crown fire, but not to spot fires as embers may be transported over the barrier. The width of barrier is set at the distance resolution in the "Model Parameters" dialog box. This is necessary so the barrier will be "seen" by FARSITE, see distance checking in the Technical Reference; Huygens Principle.
This command allows you to import two types of vector files to be used as barriers:
ARC UNGENERATE ASCII files with .BAR, .VCT, .ASC extensions or
ArcView shapefiles.
These barrier files can be create with a GIS or in FARSITE with the Simulate > Modify Map > Export Barriers command. ARC ASCII vector files must be in single precision format, no double precision values.