Friday, October 24, 2014

Railroad Timbers

Here are some interesting tidbits concerning wooden railroad timbers from a Report about the substitution of metal for wood in railroad ties. ©1890

The Grand Trunk Railway desires that a tree should average four ties, and says "it matters not whether they be hewn or sawn, so long as the upper and lower faces are flat and the sides uncut. Oak ties are taken when sawn on four faces, but no other kind." The ties used by the road—oak, tamarack, hemlock, and cedar—average six to seven years in duration.
The Detroit, Lansing and Northern Railroad, using oak with a life of eight and hemlock with a life of fiv^e years, finds no difference between hewn and sawed ties, " if made of similar timber."
The Kansas City, Fort Scott and Gulf Railroad, using oak with a life of eight years, says: "If made from large timber, no preference is had between ties that are sawn and those that are hewn. Large timber is deemed best."
The preference is given to sawn ties, and from large trees, by the Oregon and California Railroad, using red fir of eight years life; by the Bangor and Piscataquis Railroad, with cedar of fourteen and tamarack of seven years' duration (put iu track when half seasoned, although full seasoning is recognized as preferable); by the Mobile and Northwestern Railroad in Mississippi, "if all heart can be obtaiued and large timber, as it has less sap-wood. The small trees along the lino of road do not make as good ties as the large timber."
The Arkansas Midland Railroad prefers sawed ties, although they are more costly. "Cypress ties should only be sawed from large trees, post oak and white oak ties from small trees are equally as good as from large ones."
The Alabama Great Southern makes a point that the ties should "not be cut through the heart of the tree," the philosophy of which is, probably, that the long-leaf pine ties are liable to have the heart break out and sliver. The significant statement is also made that the oak from the south end of the road is not as durable as that from the mountains on the north end. The difference is probably due to track conditions rather than to locality of growth.
Durability or life of ties.—The life of timber in use as ties is reduced by two causes, namely, a mechanical one, the breaking of the wood fiber by the flange of the rail and by the spikes, and a chemical or physiological one, the rot or decay which is due to fungus growth.0 These causes work either in combination or, more rarely, independently. A soft wood may be easily out into and made useless before rot takes place— as, for instance, in the case of such otherwise durable woods as redwood, chestnut, etc., but the breaking of the fibre iu most cases is only the antecedent and forms part of the favorable conditions for the fungus growth—other timbers may be attacked by rot first, which, of course, is followed soon by a breaking of the fiber.
The exterior conditions6favorable to decay have been discussed at length in Bulletin l; the controllable ones consist mainly in the drainage conditions of the road-bed. Rock ballast is best drained, and hence the best record comes from such road-beds; gravel is next best and clay or loam is about the worst; on the other hand, where soft-wood ties, like chestnut, are used, the hard rock ballast, while unfavorable to decay, reduces their life by pounding and cutting. Sand ballast seems to vary considerably; a sharp, coarse silicious (not calcareous) sand with good under-drain age should be next best to gravel, while some reports give a heavy black soil and loam as better than sand. The reason why sand, although offering good drainage, is favorable to decay, may be sought in its great capacity for heat, which induces fermentation.
Iu Louisiana " ties on black loamy soil rot out in one-third the time of those laid in a clay soil. Ties exposed to the sun all day rot out in less time than those which are shaded a part of the day. Shade and a free circulation of air are requisite to the best lasting of any timber in our climate."
From fifteen years' experience on the Cumberland and Pennsylvania Railroad it is stated that ties supported in stone ballast have 20 per cent. longer life, as far as rot is concerned. The Eastern Kentucky Railroad claims that with slag ballast oak ties will last two years longer than in sand, while on the Cleveland, Columbus, Cinncinnati, and Indianapolis Railway such ties were found to last two years less in slag ballast than in gravel. The nature of the slag, it should not be forgotten, is very varying, and hence its value for ballast. The East Tennessee, Virginia and Georgia Railroad allows in rock ballast eighteen months longer life than in a soil bed, and notes in sandy soil the most rapid decay.
Experience on the Hannibal and St. Joseph Railroad ranges the various kinds of ballast as follows: stone ballast best; next,coarse gravel; next, soil, and worst, cinder and sand ballast.
The New York, New Haven and Hartford Railroad, six years ago, ballasted its road with broken stone to a depth of 14 inches; stone of not more than 2 inches in size was used, and at the rate of 4,000 cubic yards to the mile. It was expected that ties in such a road bed would last two years longer than in gravel ballast. Yet now it is found that, with the heavy traffic, the high rate of speed, and weight of engines and trains and the use of chestnut ties, these do not last more than live years, the cutting of the rail on the upper aud of the stone on the lower side wearing the ties rapidly.
Even the oak tie will succumb to the pounding it receives from such ballast, as the report of the Erie Railroad shows, which, while admitting that ties are less liable to decay in broken stone ballast, finds this ballast "on the heavily used portions of the line hard on the ties, by cutting, so that the oak ties are worn out before they rot."
Thus the life of ties of the same timber varies.considerably, not only according to climate, and character of the timber, and the treatment the ties receive before being laid, but also according to the character of the road bed aud the traffic. From the reports of the283 companies in 1883—which, bythe-by, are now so consolidated that the 85 companies reporting to this year's inquiry represent almost 50 per cent, more mileage than the former 283—the following tabulation has been made, showing the range and average duration of ties of various timbers under present usage. The aim of well-managed roads, of course, should be so to combine conditions of road-bed, inspection, and handling of ties, that the highest average duration at least should be obtained.
The long life given to honey locust in the table on page 25 is probably due to a misnomer, black locust being meant, as honey' locust is probably not a very lasting timber. The duration of mesquite, if sound, is claimed to be interminable.

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