The greatest load that a highway bridge can be subjected to is 120 lbs. to the square foot of surface.
TABLE OF CAMBERS FOR BRIDGE TRUSSES.
| Span. feet. | Camber. Inches. | Span. Feet. | Camber. Inches. | Span. Feet. | Camber. Inches. | Span. Feet. | Camber. Inches. |
| 25 | 0.8 | 75 | 2.5 | 175 | 5.8 | 275 | 9.2 |
| 30 | 1.0 | 100 | 3.3 | 200 | 6.7 | 300 | 10.0 |
| 50 | 1.7 | 120 | 4.0 | 225 | 7.5 | 325 | 10.8 |
| 60 | 2.0 | 150 | 5.0 | 250 | 8.3 | 350 | 11.7 |
TRAUTWINE'S TABLE FOR FINDING INCREASE IN LENGTH OF UPPER CHORD BEYOND THE LOWER CHORD ON ACCOUNT OF THE CAMBER.
| Depth of Truss. | Multiply Camber by | Depth of Truss. | Multiply Camber by |
| 1-4 span | 2.00 | 1-12 span | .666 |
| 1-5 " | 1.60 | 1-13 " | .614 |
| 1-6 " | 1.33 | 1-14 " | .571 |
| 1-7 " | 1.15 | 1-15 " | .533 |
| 1-8 " | 1.00 | 1-16 " | .500 |
| 1-9 " | .888 | 1-17 " | .470 |
| 1-10 " | .800 | 1-18 " | .444 |
| 1-11 " | .727 | 1-20 " | .400 |
TABLE OF AMERICAN WOODS.
| Kind. | Weight per cubic foot | Resistance in lbs. per square inch. | Value of s. | |
| in pounds. | Extension | Compression. | ||
| White Pine. | 26 | 12,000 | 6000 | 1229 |
| Yellow Pine. | 31 | 12,000 | 6000 | 1185 |
| Pitch Pine. | 46 | 12,000 | 6000 | 1727 |
| Red Pine. | 35 | 12,000 | 6000 | 1527 |
| Virginia Pine. | 37 | 12,000 | 6000 | 1456 |
| Spruce. | 48 | 12,000 | 6000 | 1036 |
| Tamarack. | 26 | 12,000 | 6000 | 907 |
| Canada Balsam. | 34 | 12,000 | 6000 | 1123 |
| White Oak. | 48 | 15,000 | 7500 | 1743 |
| Red Oak. | 41 | 15,000 | 7600 | 1687 |
| Birch. | 44 | 15,000 | 7000 | 1928 |
| Ash. | 38 | 16,000 | 8100 | 1795 |
| Hickory. | 51 | 15,000 | 7200 | 2129 |
| Elm. | 45 | 16,000 | 8011 | 1970 |
The above table is compiled from a much fuller one in Vose's Treatise on R.R. Construction.
TABLE OF BOLTS AND NUTS CALCULATED FOR A WORKING STRAIN OF 15,000 LBS. PER SQUARE INCH OF SECTION.
| Diameter. Inches. | Area. Sq. inches. | Strength in Pounds | Weight per Foot. | Square nut. | Thick's of nut. | No. thr's. per inch. |
| ½ | .19635 | 2940 | 0.66 | 1¼ in | ¾ in | 12 |
| ⅝ | .30680 | 4602 | 1.03 | 1⅜ | ¾ | 10 |
| ¾ | .44179 | 6630 | 1.49 | 1½ | ⅞ | 10 |
| ⅞ | .60132 | 9019 | 2.03 | 1¾ | 1 | 9 |
| 1 | .78540 | 11775 | 2.65 | 2 | 1 | 8 |
| 1⅛ | .99402 | 14910 | 3.36 | 2 | 1⅛ | 7 |
| 1¼ | 1.2272 | 18405 | 4.17 | 2¼ | 1¼ | 7 |
| 1⅜ | 1.4849 | 22260 | 5.02 | 2½ | 1⅜ | 6 |
| 1½ | 1.7671 | 25505 | 5.97 | 2¾ | 1½ | 6 |
| 1⅝ | 2.0739 | 31095 | 7.01 | 2⅞ | 1⅝ | 5 |
| 1¾ | 2.4053 | 36075 | 8.13 | 3 | 1¾ | 5 |
| 1⅞ | 2.7612 | 41415 | 9.33 | 3¼ | 1⅞ | 4½ |
| 2 | 3.1416 | 47130 | 10.62 | 3½ | 2 | 4½ |
| 2⅛ | 3.5166 | 53190 | 12.00 | 3¾ | 2⅛ | 4 |
| 2¼ | 3.9761 | 59640 | 13.40 | 4 | 2¼ | 4 |
| 2⅜ | 4.4301 | 66450 | 15.00 | 4⅛ | 2⅜ | 4 |
| 2½ | 4.9087 | 73620 | 16.70 | 4¼ | 2½ | 3½ |
| 2⅝ | 5.4119 | 81178 | 18.20 | 4½ | 2⅝ | 3½ |
| 2¾ | 5.9396 | 89094 | 20.00 | 4¾ | 2¾ | 3½ |
| 2⅞ | 6.4918 | 97377 | 21.90 | 5 | 2⅞ | 3 |
| 3 | 7.0686 | 106029 | 23.80 | 5¼ | 3 | 3 |
| 3¼ | 8.2958 | 124437 | 27.90 | 5¾ | 3¼ | 3 |
| 3½ | 9.6211 | 144316 | 32.40 | 6 | 3½ | 2½ |