wide jointsfrlled with small gravel grouted with cement; but
this is mischievous. The cement breaks up, and 'when the
blocks shrink, the filling-in is driven downwards, and when
they again get wet, they have less room to expand, the side
kerbs are driven back, and the foot-pavements are displaced,
so as to require relaying. To guard against this, a space of
about 2 in. has been left between the pavement and the kerb,
to be temporarily filled with clay or sand, which can be -cleared
out as the pavement expands. 'But cement has no affinity
for wood, and-its use, together with the wide joints that were
thought necessary to give foothold, has been abandoned.
They permitted the edgeof the block to be beaten down below
the centre, so as to produce a succession of ridges, having much
of the character of a “ corduroy ” road; Asphalted felt placed
in the joints has not succeeded. A method very successfully
adopted is to leave the end joints slightly open, and'to place
strips or laths one-tenth of an inch thick between the courses,
so that hot' pitch can be poured down to fill the joint and 'cover
the surface. The roadway is then strewn with fine sharp gravel.
Hard-wood blocks so laid expand very slightly, so 'that a space
of an inch and a 'quarter is sufficient between the kerb and
the two courses of-blocks that are usually laid parallel to it;
this, when filled with pitch, is more than enough to allow for
expansion." Paving has been laid with close joints, small
vessels of hot pitch being provided, into which each paviour
dips the blocks more or less completely before laying them;
but wood blocks are more commonly 'laid dry, a little pitch
being brushed over the' surface. The gradual 'abandonment of
the' wide joints once considered necessary for foothold will be
noticed. Soft wood seems to wear under very heavy trafhc
about five times as fast as hard wood. ' ' ' i '”
Plank Roads.-In* opening up a new country, roads, temporary
or permanent, must be 'made with such materials as may
happen torbe at hand. The plank road often used in American
forests ' makes 'an excellent' track for all' kinds of' traffic.
Upon that side of the space devoted to the road, which the
heavy traffic leading to a town will use, two parallel rows of
sills 1=5 to 'Qo ft. long, 12 in. wide and“4 deep are laid longitudinally
flatwise- 4 ft. from centre to centre, the earth being
well packed and rammed to the level of 'their'face's. ”The joints
are not opposite; a short piece of sill is put either under or
by the side of each joint. Cross-boards about 8 ft. 3 in. long
and 3 in. thick are laid' down loosely, so that groups of four
boards together will project on alternate sides ofvlthe, road
3' OIV4 in., forming shoulder to enable vehicles to'gét on to
the track at any point. The remainder of the road space is
formed as"an earthen track, 12 ft. wide, for light vehicles.
Its slope outwards may be r in r6, that of the plank road 1
in 32. If the soil is too bad for the earthen track, short lengths
of plank road of double width are made at intervals to form
passing placesj The cross boards are spiked down on five
sills, and' are sprung so as to give a fall both ways.
Log Roads.-The log road is formed across swamps by
laying young trees of similar' length ~close"together. This is
ridiculed as a “ corduroy ” road, but it is better than the
swamp. Good temporary roads may be made' by laying
down half logs roughly squared 'upon the ground, close
together 'or with spaces between of a couple of inches, into
which earth-is Wellrammed. They may be'8 or Q ft. long,
alternate logs being made to project, a foot on' each side 'for
convenience of driving on and off the track. ' H
Charcoal Roads.—When fuel is available, good roads can be
formed of' burned' materials. Clay is burned into ballast for
foundations, or'for a temporary track. In American forests
charcoal roads have been largely used. Logs from 6'in. to
2 ft. in diameter are piled' along' the whole route, the
stack being 19 ft; broad at the base, 6 ft. high and 2 ft.
broad at the top. Dry 'materials for lighting are intermixed,
and the stack is covered up with sods and earth from the side
ditches., When burned, the charcoal is simply raked down so
as to-form'a 15-ft. road of a well-rounded section. ' These roads
are dry and hard, and otherwise satisfactory. ' "
The mode of 'carrying a road across a bog upona foundation
of faggots or brushwood is well, known.~ In India- the native
roads have been made equal to heavy traffic by laying (branches
of the mimosa across the track. .V And in the great plains, Where
the soil, when dry, would otherwise be made deep in dust, this
is entirely prevented by laying across the track a coarse reed
or grass like the pampas-grass, and covering it' with 3 or 4 in.
of loam., ,,
Sand Dressing.-In carrying traffic over a clay soil a covering of'3 or4 in. of coarse sand will entirely prevent the formation of the ruts which would otherwise be cut by the wheels; and if the ground has already been deeply cut up, a dressing of sand will so alter the condition of the clay that the ridges will be reduced by the traffic, and the ruts filled in. Noiseless Roads.-A comparatively noiseless pavement may be formed with bricks made of cork granulated and r nixed with fibre and asphalt; they are set in pitch, and. seem to be suitable for rather steep gradients. For a perfectly noiseless pavement, such as is specially required wherexa carriage entrance under bedrooms is used by night, no substance is equal to indiarubber. .For this purpose it is made in inch sheets about 3 ft; wide and as long as the Width of the roadway; it is fixed over concrete and secured by iron clips. This arrangement carries the whole of the passenger traffic to St' Pancras Station, London, and also a considerable amount of traffic passing under the'Euston' Square Station Hotel.
Dustless Road.§ .~The necessity for making .roads dustless has been rendered urgent by the advent of the motor-car. The oldest and least efficacious method is to convert the dust into mud by the aid of the watering cart; at the best, however, the improvement'is temporary, though attempts have been made to obtain morelastingfresults by using a solution of some hygroscopic 'salt such as calcium chloride. Various special preparations of petroleum and other oils have been introduced as palliativesfbut the most promising treatment for existing macadam roads consists in distributing tarby hand or machine over the surface, care being taken to make the application. in fine weather when the roads are dry. The radical solution of the problem, however, is to be sought in the adoption of improved methods and materials for construction, probably with a bituminous binding or matrix.-This
same problem of the motor-car, which, -by its rapidity of movement, renderedtmany of the old country roadsin England (suitable, or at least tolerable, as they were for slow moving traffic) positively dangerous for the new traffic.by reason of their narrowness, sharp corners, &c., has been responsible for the passing by the legislature of a very important measure, the Development and Road Improvement Funds Act r9o9. This act, in its second part, deals with the question of road improvement, and establishes a Road Board, making it a body corporate. The Board is given' powers to 'make advances to' county councils or other highway authorities for the construction of new roads or the improvement of existing roads, as well as itself to construct and maintain newroads. The expression “improvement of roads ”' is defined by the act as including the widening of a road, they cutting off corners, levelling, treating a road for mitigating dust nuisance, &c. Power is given to the Board to acquire land for the purposes of road improvements. The expenses of the Board are met out of a road improvement grant each year, 'the greater part of which it was proposed should be provided by diverting the tax on motor spirit and on motor Vehicles levied under the Finance Act of 1909-ro.,
Wateringf-On 'macadamized roads in Great Britain watering is only good for the road itself when the materials are of ar very siliceous nature and in dry weather. With other materials the effect is to soften the road and increase wear. In and near towns watering is required for the comfort of the inhabitants, but it should not be more than enough to lay the dust without softening' the road, and the amount re uired for this may be greatly reduced by keeping the surface free (from mud, and by sweeping off the dust when slightly wetted. Pavements are watered to cleanse them as well as to lay the dust, but it must be remembered that both wood
