Page 44 - Moving the Earth_ The Workbook of Excavation

LAND CLEARING AND CONTROLS

1.44 THE WORK

FIGURE 1.35 Fire-fighting with dozers.

to that in Fig. 1.35. A direct attack on the front means fighting flames several feet deep. If these
should be put out, fire blowing up the sides could rekindle them in a few seconds. A crippled person
or machine ahead of the fire could not escape being burned.
Pinching off the sides is both effective and reasonably safe. The fire is extinguished starting at
the back so that the heat and smoke are blown away from the workers. Provided a constant watch
is kept behind them for rekindled spots, the fire cannot repossess the extinguished area. When the
front is reached, it is attacked from directly behind as well as on the sides.
If the fire is too strong for the force fighting it, the front will continue to advance, but the work
on the flanks will limit its width and make easier the task of stopping it with firebreaks or backfires,
or after a shift in wind direction. It can sometimes be turned by concentrating on one flank.
Firebreaks. A firebreak is any strip bare enough of flammable vegetation to delay or stop the
spread of fire across it. Roads, open water, plowed fields, close-cut lawns, and even footpaths may
be used. In addition, breaks may be prepared in anticipation of fire along the crest of hills or
mountains, at property lines, or at the edge of the areas being cleared.
Advantage should be taken of any existing breaks when deciding where to place one to stop a fire
already burning. A short line is preferable, and valuable property or highly flammable areas should
be protected. The break should be far enough from the fire to allow time to finish it and to start back-
fires; it should be in vegetation least apt to make a spark-producing or a high fire, and on terrain
favorable to operation of machinery. A compromise among these features must usually be made.
A bulldozer may be walked along the line of the break, alternately cutting and filling, so as to
mix the vegetation with dirt. Hand workers with cutting or digging tools follow, to cut out any