CONSTRUCTION.
Suitable drainage is the first requisite of a good road, as with our
climate and soil it is impossible to have a road in a satisfactory
condition at all seasons of the year unless the same is well
drained. In building a new road provisions should be made to get rid
of all surface water, and in wet land of the water in the soil, by
ditches and drains sufficient to dispose of it in a thorough manner;
and in repairing an old road it frequently happens that its
condition can be greatly improved and sometimes perfected by simply
providing proper drainage for it. It is not sufficient to have
ditches on each side of the road; for if the water stands in them it
is liable to make the road muddy and to weaken its substratum. The
ditches themselves should be thoroughly drained, and all the water
which accumulates in them should be carried into the natural
watercourses of the country, or at any rate beyond the limits of the
highway.
Every carriage-road ought to be wide enough at nearly all points to
allow two vehicles to pass each other in safety. Whether it should
be wider than that depends upon its location and its importance as a
public thoroughfare. Any unnecessary width should be avoided, except
on pleasure and showy boulevards, because thereby land is wasted,
and labor and cost in construction and repair are increased. All
important highways should be wide enough to admit of footpaths five
or six feet wide on each side, and of a macadamized or travelled way
commensurate to the public traffic thereon.
If a road is to be made wider than two vehicles require, it should
be made wide enough to accommodate one or more vehicles; for any
intermediate width causes unequal and excessive wear, and therefore
is false economy.
The road-bed should generally be raised above the level of the
surrounding land, in order that it may be as free as possible from
water; and it should "crown" sufficiently to allow all the surface
water, to find its way quickly into the side ditches. If it is not
crowned enough, it soon becomes hollow, and therefore either muddy
or dusty, and in times of heavy rains or thaws the water stands or
flows in the middle of the road. If it is crowned too much, the
drivers of vehicles will seek the middle of the road in order to
keep their vehicles in level positions, and consequently the
excessive travel in one part of the road soon wears it into ruts in
which water accumulates, and carriages in meeting are forced to
travel on a side hill, which causes unnecessary wear to the road by
sliding down towards the ditches. This sliding tendency greatly
augments the labor of the horses and the wear and tear of the
carriages. Evidently, then, the wise course to pursue in the matter
of crowning the road is to hit the golden mean. Much of success in
life depends upon striking the golden mean, for human experience
teaches that those who follow in this pathway are apt to find
themselves among the happy and the successful. The advice which the
wise old Horace made a sage seaman give two thousand years ago is
good for road-makers of to-day,--
"Licinius, trust a seaman's lore:
Steer not too boldly to the deep;
Nor dreading storms by treacherous shore
Too closely creep."
It ought therefore to be an accepted maxim in road-making that the
road-bed should be so constructed as to induce vehicles to travel it
equally in every part.
For our climate and soil, no doubt, a macadamized road is the
cheapest and best for general travel. This is made by covering the
bottom of the road-bed with stones broken into angular pieces to a
depth of from four to twelve inches. The bottom of the road-bed
should be solid earth, and crowned sufficiently to carry off all
water that may reach it. The depth of the stone coating may properly
vary from four to twelve inches, as required by the nature of the
soil, the climate, and the travel on it; and the size of the broken
stones may also be varied to meet the requirements of the road. If
there is to be heavy travel on the road, the stone coating should be
thicker than on a road over which only lightly loaded teams are
expected to pass; and in the former case the broken stones should be
larger than in the latter case. In any event, the top of the stone
coating should be composed of stones broken into small fragments. A
coating, from four to six inches in depth, of broken stones from one
to two inches in diameter is ordinarily sufficient to make a hard,
dry, and beautiful country-road, if kept up at all seasons of the
year. Flat or round stones should never be used, because they will
not unite and consolidate into a mass, as small angular stones will
do. When travel is first admitted upon the stone coating, the ruts
should be filled up as soon as formed; or what is better, a heavy
roller should be used until the stones have become well
consolidated.
Sometimes in wet or clayey soil it is well to put at the bottom of
the stone coating a layer of large stones, set on their broadest
edges and lengthwise across the road in the form of a pavement. This
is called a Telford road, and has advantages over the McAdam road in
a soil retentive of moisture, as the layer of large stones operates
as an under drain to the stone coating above it.
It is undoubtedly true that the McAdam or Telford road is the best
road for all practical purposes in this country, and will be the
country road of the future; yet it is also true that the most of our
highways are mere earth-roads, and will probably remain such for
many years, and it is therefore desirable that they should be
constructed as well as they can be made. It is an admitted canon of
the road-making art, that a road ought to be so hard and smooth that
wheels will roll easily over it and not sink into it, so dry and
compact that rain will not affect it beyond making it dirty, and its
component parts so firmly moulded together that the sun cannot
convert them into deep dust. Therefore the travelled part of an
earth-road should not be composed of loam fertile enough for a
corn-field, nor of sand deep enough for a beach. If the road runs
through sandy land, it can be greatly and cheaply improved by
covering it with a few inches of clayish soil; and if it runs
through clayey land, a similar application of sand will be
beneficial. A gravelly soil is usually the best material for an
earth-road, and when practicable every such road should be covered
with a coating of it. The larger gravel, however, should never be
placed at the bottom and the smaller at the top, as the frost and
the vehicles will cause the large gravel to rise and the small to
descend, like the materials in a shaken sieve, and the road will
never become smooth and hard.