MISCELLANEOUS ROADS - WHEELWAYS. When wheeled vehicles are drawn by horses, the wheels should move on the smoothest and hardest surface possible, while the horses require a surface rough enough to give them a secure foothold and soft enough to be easy to their feet. The two opposite requirements are united only in wheel ways, i. e., in roads in which two parallel rails of suitable material are provided to receive the wheels, while the space between the rails is filled with a different material, on which the horses travel. In ancient times, stone wheelways were of considerable impor tance; and because of this, and of the frequent proposals now-a days to build wheelways of steel and burned clay, this class of roadways will be briefly considered.
Telford made an ingenious use of wheelways on his Holyhead road (third paragraph of § 304). Two hills, each a mile in length, had an inclination of 1 in 20. To reduce the grades to 1 in 24 would have cost $100,000. Nearly the same advantage in dimin ishing the tractive force was obtained by moderate cutting and embanking and by making stone wheelways, at a total expense of less than half the amount the grading would have cost. The construction was as follows: "The blocks were of granite, 12 inches deep, 14 inches wide, and not less than 4 feet long. A foun dation for them was prepared by making an excavation 8 feet wide and 25 inches deep. On its leveled bottom was laid a telford pave ment (§ 302) 8 inches deep, the interstices being filled with gravel.
Upon this pavement were laid 3 inches of broken stones, none exceeding 11 inches in their longest dimensions. On these stones was a layer of 2 inches of the best gravel, over which a heavy roller was passed. Upon this the stone blocks or trains were laid to a very accurate level. On each side of the blocks was placed a row of paving-stones of granite, 6 inches deep, 5 inches wide, and 9 inches long. The remaining space between and outside of the lines of paving stones was filled up with hard broken stone, and the whole was covered with a top dressing of one inch of good gravel." Steel Wheelways. In recent years there have been many proposals to build steel wheelways. Numerous designs have been offered for the rail, most of which are highly impracticable, being difficult to manufacture, to lay, and to maintain. A number of
the rails would require the construction of expensive machinery for their manufacture before they could be tried even experi mentally. Three or four sections from 16 to 180 feet long have been built, and for a time were exploited in the newspapers; but even a little experience with them showed that they were prac tically worthless. A short section well cared for on dry ground under an experimental wagon gives little or no indication of the result under the ordinary conditions of actual service.
Apparently the first steel wheelway was constructed in Spain. in 1892 from Valencia to Grao—a distance of two miles. Valencia has a population of about 170,000 and Grao is the seaport. The road is a double track, and the space between the rails and adja cent to them is paved with stone blocks. The rail consists of two. inverted trough sections bolted together,* and apparently simply embedded in the sand. The cost, including the paving, was $7,665 per mile of single track. The traffic is said to be 3,200 vehicles a day. The cost of maintaining the former macadam surface was $5,470 per annum; and since the opening of the steel wheelway, the cost of maintenance is said to be but $380 a year. For several reasons, this example is not a very valuable guide for American practice.
The only practical test of a steel wheelway ever made in this country was upon a section built in Chicago in 1901 from designs prepared in the Office of Road Inquiry of the U. S. cultural Department. Fig. 67 shows the cross section proposed for the road, and Fig. 68 shows the details of the rail. The two' rails are tied together by a 2i X g-.nch bar riveted to two short pieces of 4X 3X finch angl..s which are bolted to the inside• and the outside flanges of each rail. These gage-ties are spaced 15 feet apart. The rails are spliced end to end by the breaking of the joints of the several members composing a wheelway. Owing to the impossibility of filling the underside of the rail with concrete, the road was not built according to the cross section shown in Fig. 67; and consequently the rail was filled with a 2"X 8" pine timber. About 2,100 feet of double track was laid where the traffic was exceptionally heavy. This traffic consisted chiefly of wagons heavily laden with packing-house products. The rails were em bedded in crushed limestone, and the space between them was filled with the same material. The work was done under the direction of a competent railroad engineer.