| Trains per day. | Trains per year. | No. of years’ life of rails. |
|---|---|---|
| 2 | 600 | 604 |
| 4 | 1,200 | 302 |
| 6 | 1,800 | 201 |
| 8 | 2,400 | 151 |
| 10 | 3,000 | 121 |
| 12 | 3,600 | 100 |
| 14 | 4,200 | 86 |
| 16 | 4,800 | 75 |
| 18 | 5,400 | 67 |
| 20 | 6,000 | 60 |
| 30 | 9,000 | 40 |
| 40 | 12,000 | 30 |
| 60 | 18,000 | 20 |
| 80 | 24,000 | 15 |
| 100 | 30,000 | 12 |
Probably one half of the above numbers of years would show the full life of rails upon American roads.
As those rails which are most used wear out the soonest, they should be made accordingly heavier. Such are those at depot grounds and at sidings.
Note.—From the reports of the Reading (Penn.) Railroad it appears that in 1846 153
209 of the damaged rails were split; and that in 1845 285
295 were split.
As regards the quality of railroad iron, it is generally notoriously bad, and its makers know it as well as those who buy it. Railroad companies are not willing to pay for good iron. Comparisons between American and English iron amount to little. First rate iron can be made in England or in America, and so can that which will last about two years. Time will convince companies that the most expensive iron is the cheapest.
TABLE OF THE WEIGHT PER MILE OF DIFFERENT RAILS.
| Weight in lbs. per yard. | Tons per mile. (2,000 lbs.) | Tons per mile. (2,240 lbs.) |
|---|---|---|
| 50 | 44.00 | 39.29 |
| 55 | 48.00 | 43.21 |
| 60 | 52.80 | 47.19 |
| 62 | 54.56 | 48.71 |
| 64 | 56.32 | 50.28 |
| 66 | 58.05 | 51.86 |
| 68 | 59.84 | 53.43 |
| 70 | 61.60 | 55.00 |
| 72 | 63.36 | 56.57 |
| 74 | 65.12 | 58.14 |
| 76 | 66.88 | 59.71 |
| 78 | 68.64 | 61.28 |
| 80 | 70.40 | 62.86 |
TRACK-LAYING.
289. As wrought iron expands 0.0000068 of its length per degree (Fahrenheit) of heat, a change of 130° will cause the following expansions:—
In a 15 feet rail .0135 ft.