The Farmington times. (Farmington, St. Francois County, Mo.) 1905-1926, 1917-06-29

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maximum grade usually is fixed will
reference to this feature about as fol
lows:
Per cent
Coastal plain and prairie regions. :. q to
average rolling country .......,,...,,4 to
F1illy or mountainous regions......,.6 to
The question of minimum grade Il
OF Importance only as regards the side
bitches. These should have adequate
fall to empty the water that collects
In them at sufficiently rapid rate 10
prevent damage to the road. Ordlnar.
lily 1t is desirable to give the side
bitches fall of about one foot per 100
rect OF length, though a somewhat less
fall has proved satisfactory some
times.
Wherever changes in grade occur
the change should be made by means
Of vertical curve, and not by an
abrupt angle.
Slopes.
The slope at which earth will stand
when faced up In a cut or placed in an
embankment depends "a on the char
acter of the earth and (2) on the eli
mate. In cuts, good quality of non
shaking clay usually will stand on a
slope of about 45 degrees, or, as slope
Is expressed usually, one horizontal to
one vertical, even where fairly deep
freezing occurs, and in some of the
Southern states such material has been
known to stand for many years on
slope Of less than One-half to one, On
the other hand, clay that Stakes very
easily, may require slope of three to
one, or even four to one, under the most
favorable condition of climate, but
this latter extreme Is very unusual.
The usual slope for clay In cuts Is one
to one in warm climates and one and
0ne-half to one in cold climates.
While in the case of entertainments
clay usually can be deposited on an
initial slope of about one to one, this
steep slope seldom can be maintained
unless the material is of an exceptional
quality and the climate very favorable.
Ordinarily clay embellishments should
have a slope of about two to one In
cold climates and at least one and one
half to one In warm climates; and If
the clay be of questionable quality |
these values should be increased. EN-
bankment slopes require more care in
than excavation slopes, |
because any fattening of an embank.
ment slope by the action Of weather
after the road is completed is very
likely to damage the road surface
while the sliding In of excavation
slopes usually does no further damage
than to obstruct the side bitches,
which can be reopened readily.
Sand of average quality usually re.
luires a slope Of about two to one in
cuts and three to one In embankments
regardless of climate. Moderately
coarse sand mixed with gravel will
stand on sleeper slope than fine
sand, because the former Is not moved
70 readily by the action of storm wa.
er.
Solid rock excavation usually can be
lone on an average slope of about one.
ourth to one, except where the rock
occurs in sloping strata separated by
lippery clay seams. In the latter case
he average slope may be as much as
ne-half to one or three-fourths to one.
The faces of rock cuts usually are not
ressed down to even an approximate.
= smooth slope, as Is done in earth
uts. In excavatlng solid rock only
UGH material Is moved as Is actually
ecessary to obtain the desired width
t the bottom of the cut or as has been
oosened In blasting. The faces should,
course, be cleared of all material :
hitch is loose, or which might be
subsequently by frost and
Tide down upon the road. Stone EN-. n
ankments usually will stand on
ope of about one to one.
In order to prevent damage by wash. .
ig all earth slopes in either excava.
on or embankment should be protect.
! by growth of grass as soon as
racticable after they are formed.
In many localities where the soil is p
rifle and a good quality of grass is i
alive no seeding Of the slopes is nee 8
sary. In other cases the soil may not 9
assess sufficient fertility to grow Y
ass, even when the slopes are seed. n
!. and in which event 1t may be very y
'sirable to cover the slopes with cut u
d. This latter process usually is =
ny expensive. and should be EN-, i
Dyed only where 1t is known thai
orough seeding and fertillzlng woulG B.
II to secure a covering of sod.
precaution frequently neces
ry In order to prevent the washing
ray of excavation slopes is to inter
pit water from the natural grount, an
rface which otherwise would flow te
wn over the excavation slope. This la
done by means of a ''berm" ditch do
Instructed well back from the top o, an
E slope. Figure 8 illustrates a con III
ion which makes a "berm" ditch is
sirable and also shows how such de
ch is constructed. oil