The Farmington times. (Farmington, St. Francois County, Mo.) 1905-1926, 1917-06-29
prepared by the United States Depart-
nent of AQricuIfura \

! prepared by the United States Depart
ment Of Agriculture)
The minimum width to accommodate
, safely two lines of average horse
drawn traffic is IA feet, and for auto.
mobile traffic the width preferably
should be not less than Is feet, though
a width of is feet is used frequently.
In order to maintain the Travelled way
to the required width and to afford
proper safeguards against accidents, it
Is necessary to provide shoulder not
less than three or four feet wide along
each side of the roadway proper The
shoulders may have somewhat Steep
er crown than the rest of the road
surface, but they should be sufficiently
fiat not to endanger traffic using them
and really should constitute an addi-
tional width of roadway. This means
that the total width of roadway be-
tween side bitches never should be less
than 20 feet where hOrse-drawn traffic
predominates, and "a feet where any
considerable volume of automobile
traffic Is to be accommodated.
Where sharp curves occur in the
alignment it is desirable, though not
customary, to increase the width of
the Travelled way. A vehicle being
drawn along curved road tends to oc-
cupy an appreclably greater width
than where the road is straight, and
unless the width of the Travelled way is
Increased correspOndlngly, this ten
dency contributes materially to the
hazards that invariably accompany
sharp curves. The minimum widths
given above should also be increased
on embellishments Of any considerable
depth, so as to make maintenance
easier and at the same time diminish
the danger Of accidents.
The width Of right Of way required |
to provide all necessary area for the
roadway, slopes and bitches, varies
considerably with the nature of the
topography.
Grades.
In designing public road one of the
most difficult problems to solve proper
ly Is the question Of maximum allow
able grades. In deciding this question,
the advantages to be gained by reduc-
ing all of the sleeper grades on q par
ticular road to a given maximum
should be weighed against the addl-
tional cost which the reduction in
wolves.
mn
The following data and suggestions
are intended to aid individual judg-
ment, which necessarily must be the
prime factor in solving this important
problem:
l. The cost Of average pleasure traf-
&C. horse-drawn and motor, is practi-
cally unaffected by grades of not more
han 6 or z per cent (six or seven feet
Use per 100 feet, measured horizontal
", provided the conditions are such
hat 1t is unnecessary to apply the
brakes to vehicles when descending ,
he grades. But for traffic where loads ,
ire as important as speed, even very :
light grades may be of considerable !
2. Increasing the steepness of Z
'rade decreases In three distinct ways
he load horse can haul: (a) for the 4
anne character of surface, the required Z
ractive effort or pull per ton of load q
increased by about 20 pounds for 8
ach per cent increase in grade, (b) +
he possible pull the horse can exert is n
ecreased by an amount equal to the 7
fort required to lift his own weight 4
through the rise. This amount is ap- I,
roximately equal to one one-hun- =
redth of the horses weight for each G.
er cent increase In grade, (c) the eff n
ective pull of the horse is reduced by a
ne change in the angle at which the II
ull is applied. =
y. The pull horse can exert on q | "
vel road varies greatly with the in lc
lvidual animal, and is affected by the 81
anner of hitching and the skill of the h
river. The character Of the road 81
irface also may have an important
lfuence by affecting the security of IN
lie horses foothold. N
Tests made by the office of public o,
'ads and rural engineering indicate n,
lat, on a level road, average farm
'rses unframed to the road can exert fe
steady pull for several consecutive n,
ours equivalent to from 0.08 to O.1O es
their own weight without undue nc
tigue. and that by resting at inter- Of
lis of from 500 to 600 feet they can ed
.ert pull equivalent to about OPS dc
their weight, provided the foothold so
good. va
4. The tests referred to above also nj
dicate that with well-constructed tn
lgos the pull required to move ia
oss load Of one ton over level road
ries about as follows: so
Pounds nv
ose sand road .............,,,,,...... 315 ="
erage dry earth road varies ce
reatiyl .e........................ .15O en-
m earth Or sand-clay road .....,.... los gu
erage gravel road ................S0 do
st-class gravel or macadam road. J. IS Il
In general, the judgment should be co,
gely influenced, in fixing the maxi III,
i'm grade. by the topography Of the dit