. A manual of the principles and practice of road-making: comprising the location, consruction, and improvement of roads (common, macadam, paved, plank, etc.) and rail-roads . s wide, and 12 inchesdeep. The space between them was paved.* * Parnell, p. 106 258 IMPROVEMENT OF THE SURFACE. A similar trackway of stone has been used with greatadvantage to facihtate the ascent of a steep hill, as a substitule for reducing the inchnation. Upon the Holyheadroad, two hills, each a mile in length, had an inclinationof 1 in 20. To reduce this to 1 in 24 would have cost^100,000. Nearly the same advantage,
. A manual of the principles and practice of road-making: comprising the location, consruction, and improvement of roads (common, macadam, paved, plank, etc.) and rail-roads . s wide, and 12 inchesdeep. The space between them was paved.* * Parnell, p. 106 258 IMPROVEMENT OF THE SURFACE. A similar trackway of stone has been used with greatadvantage to facihtate the ascent of a steep hill, as a substitule for reducing the inchnation. Upon the Holyheadroad, two hills, each a mile in length, had an inclinationof 1 in 20. To reduce this to 1 in 24 would have cost^100,000. Nearly the same advantage, in diminishingthe tractive force required, was obtained by moderatecutting and embankment, and making stone trackways, ata total expense of less than half the former amount. Todraw one ton over the original hills required a power of294 lbs.; to draw it over the trackways laid on the sameinclinations required only 132 lbs.; so that the tractiveforce was reduced more than one-half by this improve-ment ; and the effect was the same as if the hill had beencut down to a level, its surface remaining arrangement of this trackway is shown in Fig. 118. Fiff. I I I I I I I I I I I I St I I i t n^ .mi^?smmm&mmm: r^. ^^^^m^^^ fSS u B^rjuS im^ The blocks were of granite, twelve inches deep, fourteeninches wide, and not less than four feet long-. A foundationfor them was prepared by making an excavation, 8 feet wideand 25 inches deep. On its levelled bottom was laid a roughpavement (like that described for the Telford road, page210) eight inches deep. The joints were also filled withgravel. Upon this pavement were laid three inches of brokenstones, none exceeding one and a half inches in their longest ROADS WITH TRACKWAYS. 259 dimensions. On them was a layer of two inches of the bestgravel, over which a heavy roller was passed. Upon this thestone blocks or trams were laid to a very accurate spaces between and outside of them were filled up to adepth of six inch
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectrailroa, bookyear1853
