The Jasper weekly courier. [volume] (Jasper, Ind.) 1858-1922, 1893-04-07

Important Points 20 ne Observed IN Sub
pavement and TOP Course.


pavement and TOP Course.
Tho system OF Thomas Tclford. whose
Iaino has been used to designate the kind
" road which he advocates. differs from
the Nacadam system in many pariicn-
.ars. tho most important q which pro
scribes the use Of subpavemont of large
stones set in courses upon the earth
foundation. In the interstices between
tho larger stones should be carefully and
thoroughly wedged and packed with
smaller stones, as it insures the solidity
of tho subpavomant and serves 10 pre-
vent the dropping or settling of the MI
terials that are subsequently put on.
When finished. the subpavement should
present n general uniformity Of outline
with rough surface caused by the IN
even edges Of the pavement stones-a
roughness which serves 10 prevent the
shifting and sloping of the smaller stones
above and TO insure the compact binding
together Of the entire structure.
In tho making of telford road it Is
importan. 10 remember that the stones
used in tho subpavement need not be Sc
that stones may be used in this part Of
the work which would be wholly IN
suited 10 situations where they might DO
exposed 10 direct contact with heavy We
hicles. Another practical point to be
remembered in the laying Of the sub
pavement is that the driving and wedg-
ing Of chips and smaller stones into the
interstices Of the subpavement must not
be permitted near the face of the unfn-
ishel work. rs this practice would result
in the loosening and forcing apart Of the
larger stones Of the subpavement.
After the completion of the subpaye-
ment at least two separate layers of
broken stone are generally put on to form
the upper and finishing course Of the
roadway. The intermediate course next
TO the subpavement is made Of broken
stones somewhat after the manner of
macadam material. although these need
not be. and in practical work generally
arc not. Of tho same uniform size and
quality rs are required for the finishing
layer. The stones used in the intermedi-
ate course may vary in size from inch
to inches in their largest diameter. and
this course should be nj least 4 inches
thick. free from dirt. and laid in q bed
o: uniform thickness to preserve the
regular contour Of the roadway.
IL putting down this course the heavy
roller should again be employed TO COM
pact and consolidate the stones. so that
the repeated passing Of the roller over
its surface will produce no settling, hol- \
lows or uneven places. Before complet-
ing the rolling quantity Of clean. sharp
sand should be laid on the surface of the
intermediate course, evenly and in suffi-
oient amount. and over this the roller
should be passed repeatedly. after hay
ing arst sprinkled the sand with a sufii-
Gent quantity of water 10 pre-ent its
sticking to the surface Of the roller.
The top or surface course is the finish
ing work in the building Of teisord |
road. and in the making Of this cOu e
great care must be had both IN selecting
the material to be used and in the method |
Of laying it down. All the stones of this |
course should be of uniform size, and all /
stones should be rejected from this ma
terial which are too large to pass through |
q ring having an inner diameter of two
inches. If trap rock can be obtained for
this course. it can be used with the as
surance that better material is scarcely i
obtainable. but If trap rock cannot be
had there are several varieties Of hard
granite and limestone which make tx
cellent substitutes and which are fire.
quently used with success.
The top or surface course should be
laid with n uniform depth of not less
than inches. and after being compactly
rolled it should show a thickness Of at
least inches above the intermediate
course After the loose stones for the
top course have been evenly laid over
the surface Of the intermediate course,
so as to show the form Of the completed
roadway. the roller should he run over
the new surface just enough TO render 1t
moderately compact, and for this pur-
pose light roller will be sufficient.
Then light coat Of clean. sharp sand
should be put on and sprinlled as in the
case Of the intermediate course, after
which, BY the use Of splint broorns. the
sand may be worked in between the
stones Of the surface. while the heavy
roller Is made TO follow. pressing the
small stones firmly into compact mass
The rolling should proceed backward
and forward in line with the direction Of
the road, beginning at the side or cutter
Of the roadway and working toward the
center The process Of rolling and add
ing moist sand should continue until
each stone becomes SO firmly beddcd and
the finished surface 50 hard that more
sand cannot he pressed into the surface,
after which all loose material remaining
on top Of the road may be removed, so
as to leave the surface smooth and COM