Tessellated pavement

“ The asphaltum pavement is clean and fit for traffic a few hours after being laid, while new or repaved stone roadways must be covered for months with heavy layers of sand, to be drifted by the breeze in dry weather and added to the mud in rainy spells. Repairs can be made to the asphaltum pavement in dry days of a cold winter, while with stone pavements any defects must be endured until spring. ”

“ Broken stone or gravel foundations may serve the purpose fairly well upon a street of light travel, but it should never be used on streets of considerable or heavy travel. Its lower first cost is the only thing in its favor, but this will, in nearly every case, be more than offset by the better service and greater durability of the pavement, even on streets of light travel, if laid upon an adequate hydraulic concrete foundation. ”

“ But in all cities and towns there are many residence streets where the travel is very light, and yet where a permanent pavement is wanted and warranted. For these, it is believed that a properly constructed concrete pavement will prove very satisfactory and durable, and the low cost at which it can be constructed should make it very attractive to city officials and property owners. ”

“ Wood's patent, enrolled in April, 1841, shows a pavement made of adjoining blocks fitted together, but alternately larger and smaller at the top, like the frustrum of a pyramid, and not parallel-sided; those larger at the top standing slightly higher than the others, so that when pounded down, or pressed by rollers or loaded vehicles, they would act as wedges, binding the whole pavement more tightly together. No filling is used on the surface, and no prepared foundation is suggested. ”

“ A poor asphalt pavement offers one of the best opportunities for the study of the formation of various kinds of cracks and fissures. On the edge of a sloping sidewalk one may see the cracks due to a sliding, or lateral displacement of the surface; the effects of subsidence show a number of cracks around the area of depression; the growth of a tree crowding the asphalt shows the effect of lateral thrust, and an enlargement of a root below, or the effects of frost show cracks due to elevation. ”

“ The practice of opening the street to travel for a period after the blocks are relaid and before the asphalt surface is applied, helps, under favorable conditions, to consolidate the foundation, but does not remove the objections to it. If heavy rains intervene, the sub-foundation becomes saturated with water, and its resistance so reduced that the stone blocks settle out of shape, particularly in soft spots, and they are usually hastily raised and reset just before the asphalt surface is applied. The result is an insecure foundation fatal to the durability and usefulness of the pavement. ”

“ The popularity of this pavement in the two largest cities of Europe, where, with immense traffic and most extensive experience on the relative value of pavements, the demands on the municipal authorities are inexorable, serves as a proof that smoothness of surface does not cause any danger with this material. Being elastic but not soft in summer, and hard but not brittle in winter, it possesses with a slight yield the power of readjustment in a high degree, so that horses and drivers ever seek it, if it is "laid intelligently by practised bands, with a low crown" or flat profile. ”

“ The practice, usual in many cities, of adopting general specifications requiring a standard thickness of foundation and composition of concrete, and applying these to all streets, regardless of the quantity and character of travel which the pavement is expected to carry, is illogical and often very wasteful. ”

“ The attempts to prevent the formation of ruts by setting blocks alternately as headers and stretchers is not always successful, even when the work is well done, and the difficulty of properly compressing the tongues of asphalt between the headers is so great that it is usually not well done. The asphalt settles under travel or is gouged out, leaving a streak of rough pavement, and the difficulty and cost of repairs is considerably increased. When paving blocks or bricks are used, they should be firmly and carefully set in the concrete foundation. ”

“ For many years the system of cleaning 19there has been hand patrol without sprinkling, except a very light sprinkling, just enough to lay the dust, not to convert it into mud—immediately in advance of night sweeping.
“Fifth Avenue, New York, is always dry except during rains, and we find one of the most durable asphalt pavements in the world. The pavement is always clean and never dusty.
“Asphalt pavement on Alexander Street, Rochester, New York, laid in 1885, is still in existence and has a record for low cost of repairs, and has until quite recently been free from street sprinkling. ”

“ Sheet-asphalt pavements seem well adapted for city streets and roads where there is a medium or dense traffic. With a firm foundation it stands up well under the heaviest traffic. Its popularity is truly deserved. The pavement under some conditions of moisture is inclined to be slippery but when dry is not. ”

“ To reach perfection a street pavement should be cheap to construct, durable, easy to repair, easy to keep clean, smooth, safe for traffic, noiseless, and attractive in appearance. Unfortunately there is no type of pavement possessing all these qualities. A pavement of granite blocks will last for many years under heavy traffic, but it is expensive to build, noisy, and hard to keep clean. The asphalt pavement is cheaper, cleaner, and easier to drive upon; but it is slippery in wet weather and breaks down very quickly when heavy traffic is allowed on it. ”

“ If such a standard foundation is sufficient for the streets of heaviest travel, it is obviously a sheer waste of money to use it on the suburban streets carrying the lightest travel. It is therefore better in preparing standard specifications for pavement in any city to leave blanks for the ratios of the concrete and for the thickness of the foundation, to be filled in, in each individual case, as the judgment of the engineer may dictate. ”

“ Where the results have been unsatisfactory, the cause can generally be traced to unsuitable materials or unskillful construction, the result of ignorance or carelessness on the one hand, or of the attempt to reduce first cost below normal figures on the other. Many people are searching for a pavement or roadway that will have all the good qualities of the standard pavements but can be built about as cheaply as a common macadam road. ”

“ The manufacture of the mixture for sheet asphalt pavement, and the laying of it on the street, involve a number of separate elements or operations. The quality and durability of the pavement 102will depend largely upon the skill, intelligence and accuracy with which each and all parts of the work are carried out. The inspector, both at the mixing plant and on the street, must give constant and intelligent attention to the work. ”

“ I believe that repairs required to all classes of pavement are more generally the result of wetting down the dirt, leaving the surface in a more or less muddy condition than by traffic, or rather what would be traffic under dry cleaning conditions. A city or street in or on which sprinkling or other methods of continual wetting of pavement surface has not been practised is almost usually one where the pavements are the best of their kind. Washington has the enviable reputation of having the most durable pavement of all kinds. ”

“ The pavement is torn up: a hole is dug in the street; the tree is planted, pulled up to its elevation, firmly fixed in the ground—although, by the way, in many instances, the poor tree of liberty looks in a very tottering state—and the havock committed in the pavement more or less repaired. ”

“ The auxiliary strip may be about half the height of the principal block; but it must not be permitted to fill up the grooves permanently and entirely, when the pavement is completed, or to perform any part of the pavement.' The strips used by the defendants are substantially the same as here described, and perform the same office. The only difference in their construction and application between the blocks is, that they are bevelled, by being made wider at the top than at the bottom,-the extra width of the top part being let into a notch or groove in the blocks. ”

“ The present condition of the road is most unpromising. Nearly every contractor has formed his bed in the valley made by the removal of the old pavement, the consequence of which is, that, with the mild season and rainy weather, the bed is not drained, nor can it be, until the side roads are cut down to the bottom of the stone strata—a measure I directed as the only means of correcting the evil. ”

“ They are to be set on their broadest edges lengthwise across the road, and the breadth of the upper edge is not to exceed four inches in any case. All the irregularities of the upper part of the said pavement are to be broken off by the hammer, and all the interstices to be filled with stone chips firmly wedged or packed by hand with a light hammer, so that when the whole pavement is finished there shall be a convexity of four inches in the breadth of fifteen feet from the centre. ”

“ Experience seems to have proved that cement grout is, everything considered, the best and cheapest filling for the joints in brick pavement. If the filling is properly done, the edges of the brick are supported and the corners do not chip off. With the expansion joints provided at intervals by the bituminous-filled joints, the curbs will not be forced out of line, nor will the pavement be raised from its sand bed by expansion, causing the rumbling sound sometimes noticed. ”

“ All, therefore, that there is left for the invention described in the first and third claims to cover is the making of the lower ends of a portion of the blocks of which the pavement is composed in wedge shape, and the driving of these wedge-shaped blocks below the general under-surface of the pavement into the sand or earth-bed on which it rests, so as to pack it and render it solid and unyielding. ”

“ Of asphalt sidewalks, etc., Paris has three million square metres, equivalent to four hundred miles of walks, seventeen feet wide. New York city can boast of only a few small and isolated strips of asphaltic street pavement, her past experience with the "poultice pavement" having induced the authorities to prohibit the laying of similar pavements. In front of the Brevoort House, and the Hotel Brunswick, samples of compressed pavement may be seen, while the American mastic, or Trinidad, has recently been laid in Fifteenth Street, between Fifth and Sixth Avenues. ”

“ With regard to the price of asphalte mastic footpaths, this [110] is quite a local question, and is not worth while discussing. The life of a footpath thus treated may be reckoned at about 15 years under ordinary traffic; the concrete will remain untouched and what is left of the asphalte may be remelted, so that a renewal is not so costly as the first expense.
Yorkshire Flagging. —This pavement is too well known to need any description from me; it is an excellent pavement in many ways, and is most pleasant to walk upon, there being a cling or foothold not experienced in any other material. ”

“ The advantages of good roads, when compared with pavements, are universally acknowledged; the extension of pavement is therefore to be deprecated as an actual evil, besides the greatness of the expence. Pavements are particularly inconvenient and dangerous on steep ascents, such as the ascent to bridges, &c. A very striking example of this may be observed on the London end of Blackfriars Bridge, where heavy loads are drawn up with great difficulty, and where more horses fall and receive injury, than in any other place in the kingdom. ”

“ No other smooth surface pavement in any country has withstood the conditions existing on Fifth Avenue with an equally satisfactory result.
The third type of Trinidad sheet asphalt pavement is that found on the Victoria-Thames Embankment in London, the first portion of which was put down by the writer in 1906, upon old macadam and a course of Trinidad asphalt concrete. ”

“ Granite block pavement is, as a rule, used upon, and appropriate for streets of the heaviest class of travel, and should, therefore, be provided with the best and strongest foundation. It is nearly always poor economy to lay granite blocks upon a broken stone, gravel, or sand foundation. ”

“ In Salford, Manchester, etc., I believe “Woodward’s Patent Molten Ironstone Blocks” are used with some success where there is not any very exceptionally heavy traffic.
One of the principal reasons of durability in asphalte pavement is its elasticity, and it should be remembered that compressed asphalte does not begin to “wear” until all compression has ceased; this is the case with no other system of pavement—stone and wood both begin “wearing” from the day the traffic commences. ”

“ Among engineers there is quite a wide difference of opinion as to the proper spacing of expansion joints, and, in fact, as to the necessity or advisability of providing them at all. It has been suggested that it might be better to omit them entirely, allowing the pavement to form its own expansion joints by cracking along lines where natural forces dictate. Such cracks by their irregularity give a bad appearance to the surface, but observation seems to indicate that the edges of these natural joints wear as well as those made by expansion joints. ”