The Works Department of the City of Hamilton has solved a question that is perplexing a great many American cities, viz., pavements, and in the tar macadam, which is now being laid on many of the principal streets, they have a pavement almost equal to that of Bermuda asphalt at about one-fifth the cost, and almost every week large delegations from American cities come to inspect it and always return feeling satisfied that the Hamilton pavement in quality and price is the pavement of the future. There was also Iaid in Hamilton during the year 1902 about thirty-five miles of cement sidewalks. and in 1903, 22 miles, there being in all about sixty miles of these walks in the city.
MODE OF CONSTRUCTION OF TAR-MACADAM ROADWAYS
The sub grade was first rolled with a la-ton roller, and any soft spots revealed were filled up and rolled until the whole surface had been worked to the proper grade and cross section, care being taken to keep the sub grade as also each succeeding layer of material parallel with the finished cross section of the roadway.
The bottom course or stone foundation six inches in depth was next put in place.
This consisted of stone varying from 6 inches to 12 inches laid roughly by hand on their natural or flat beds, after which stones of a smaller size were put on top and broken roughly in place, so that all the larger voids in the foundation stones were filled.
This course was then rolled similar to the sub grade, care being taken as before stated to keep the cross section true.
The broken stone was now brought to the work and the process of tarring was gone through as follows : Tar kettles, in which the tar w as kept at the workable temperature and consistency, were placed conveniently to mixing boards similar to those used in mixing concrete.
The stone to be tarred was placed on the board. and the tar applied to the stone by scattering -with a swinging motion from a dipper fastened to a wooden handle of a convenient length to reach w ell down in the tar kettle.
After the first application of tar the pile of stone was turned over twice by shovelling, the shovels being kept hot to facilitate the process. The operation of tarring was again gone through with alternate turnings of the mass until no bare spots could be seen on the stones, or in other words, until each stone had a coating of tar.
SPREADING TARRED STONE
To give the best results, the broken stone must be entirely free from moisture before being tarred. As soon as the stone and tar had been thoroughly incorporated it was wheeled onto the roadway and raked into conformity with the cross section.
It was found that if the rolling of this course were left for two or three days after being placed on the road it required more rolling to compress and did not bind so firmly as when rolled soon after being laid, or as soon as a stretch of sufficient length to operate the roller economically had been laid. The stone used in this course was broken of a size to pass through a 2 1/2-inch ring, and was laid to a depth of five inches as nearly as possible before rolling.
The third or top course was composed of gravel screened through a 3/4-inch mesh and mixed ith tar, about 20 gallons of tar being used to one cubic yard of gravel. This was mixed in an asphalt mixer and brought to the work hot, scattered over the roadway, and raked in very carefully, the utmost care being taken to get the surface to true grade and section, none but the most experienced men being employed in this portion of the work. The whole was then rolled, after which screenings from the crusher were scattered broadcast over the surface to be worked in by traffic, the object being to harden the surface of the pavement and to give it a more pleasing color than the dead black of the tar.
The curbing with this pavement is Portland cement concrete. The usual method of construction was reversed inasmuch as the curbing was laid after the pavement had been constructed ; the reason being that It was found to be much easier to set up the moulds for the curb, the pavement being used to place the edges of the mould boards upon. As soon as the curb had set the moulds were taken off and the ragged edges between the roadway and curb filled in with concrete and finished with cement mortar.
The method of constructing sidewalks outside the tree line and immediately alongside the travelled road has been employed here very extensively, and wherever this is done the curb is combined with the sidewalk. Whenever possible the tar-macadam has been laid before the sidewalk, so that the walk might not be disfigured with tar.
This class of pavement has proved to be particularly well adapted for residential streets, and streets where the traffic is spread evenly over the whole surface, but it is not satisfaceory alongside street railway tracks, where the traffic Is confined to a narrow space on each side of the tracks.
SCREENINGS ON TOP OF FINISHED ROAD.
In several stretches put down here in 1899, along the Street Railway tracks, the pavement shows distinctly the marks of excessive wear.
No repairs have as yet been made on any of the pavements laid within the last three years. Some pavement, similar in construction put down by the local Gas Company eight or ten years ago, has been recently resurfaced at a cost of 25 cents per square yard, no repairs being done up to that time.
The advantages of this class of pavement may he unlined up as follows : Economy in construction, he average price for 1901, with labor at 18 cents per tour, being $1.06 per square yard ; good foothold for horses and absence of dust, therefor economy in leaning and sprinkling.