Page 358 - Moving the Earth_ The Workbook of Excavation

ROADWAYS

8.20 THE WORK

When a steep hill contains boulders, stumps, or ledge, sidecasting is preferred to hauling, and
dozers will probably be both safer and more economical than scrapers if short or medium hauls
are required.
Pioneering is done by dozers. If the cuts are in material they can handle, scrapers take over the
job. In very rugged terrain, crawler tractors with standard or undersized scrapers are preferred, as
they can work on the steepest grades and need minimum turn space. After grades are reduced to
20 percent, self-powered scrapers can take over, if the haul is long enough to justify their use.
For rubber-tire jobs, turnarounds should be kept nearly level, and machines should be driven
directly up and directly down the grades. Overhung scrapers are in their most vulnerable position
in regard to overturning when turning downhill on a side slope.
Compaction. When a wide road is notched into a hillside by cut-and-fill methods, it may be dif-
ficult or impossible to compact the fill if it is sidecast.
If compaction is required, two pioneer notches may be made (Fig. 8.14), at the top and the bot-
tom of the cut. Scrapers are then used to cut the top down and build the bottom up. Compaction
of the fill can be handled by rollers following the scrapers, until sufficient width is obtained to
permit them to pass the scrapers on the fill, after which they can operate in both directions.

FIGURE 8.14 Parallel cut and fill.