Page:Popular Science Monthly Volume 88.djvu/780

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��Popular Science Monthly

��roads. These trees must usually be planted where the conditions are not favorable to them. Where such adverse conditions are encountered, better results in the growth of the trees are obtained when each hole is blasted.

In heavy road construction the steam

Appropriate method of loading for side hill cut and fill

���Loading for side hill cut when material is to be wasted

���shovel is playing an important part. Light tractor rigs are employed. These dig slowly and with difficulty in hard ground. On actual count it was found that under such condition the dipper was not filled more than one time out of

���A common road trouble and the remedy- five. This slowed up the work. Blasting ahead of the shovel will loosen the ground so that it can work to capacity.

The demand for hard surfaced roads creates a need for millions of tons of crushed stone. This is blasted out of the quarries. In some sections remote from operating quarries, the stone is obtained by blasting hard boulders out of the fields. Occasionally a rock cut affords an excellent source for stone, and gives the additional advantage of cheapening the cost of construction by making use of the most expensive material to excavate.

���When crooked or shallow streams are paralleled or crossed it is often cheaper to correct the stream than to elevate the road to a sufficient height to keep it out of trouble.

A great part of the filling up of stream courses is caused by logs and other floating material forming rafts and sand bars in the channels. Another fruitful source of trouble is from outcrops of rock which divert or impede the nor- Loading a rock-

mal flow of the ledge outcrop

current. Overhanging stumps and trees along the banks lend still further ob- struction. Sharp bends in the course of the stream check the current and cause trouble by forming sand bars.

Any and all of these troubles may be overcome quickly and at reasonable cost by the use of dynamite for shooting out the rafts and logs, and blasting a sufficient channel through the confining rock. A well-placed blast will cause the overhanging stumps to vacate immedi- ately.

Cutting off sharp turns in the channel will take a little more time and should be well done in the beginning. Locate the line of the new cut-oft' and blast a ditch that will at all times carry a part of the flow. When this is done and the rafts and logs are out of the way above and below, all there is left to do is to wait for heavy rains to flood the streams. The increased velocity of flow will cause the water to cut and wear away at the bottom of the channel as well as at the sides. From time to time it will be best to go over the stream and make sure that no new obstruction is being formed.

���A good use for blast holes

��Loading top-rot- ted stump

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