| ECONOMICS OF SUSPENSION BRIDGES | 279 |
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Mayarí Steel Comparison.
1,000-Foot Span.
From Fig. 29c we can make for the wire-cable structure the following estimate:
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| Wire cables | 4,300 lbs. @ 23 ¢ | = $989.00 |
| Nickel steel | 12,200 " @ 11 ¢ | = 1,342.00 |
| Plain concrete | 94 cu. yd. @ $16.00 | = 1,504.00 |
Mass of bases | 28 " @ $35.00 | = 980.00 |
| Total | = $4,815.00 |
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From Figs. 29d and 29e we have for the Mayarí steel the following
estimate.
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| Mayarí steel | 14,400 lbs. @ 10 ¢ | = $1,440.00 |
| Nickel steel | 8,600 " @ 11 ¢ | = 946.00 |
| Plain concrete | 98 cu. yds. @ $16.00 | = 1,568.00 |
| Mass of bases | 28 " @ $35.00 | = 980.00 |
| Total | = $4,934.00 |
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2,000-Foot Span.
Wire-Cable Structure
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| Wire cables | 8,500 lbs. @ 23 ¢ | = $1,955.00 |
| Nickel steel | 18,000 " @ 11 ¢ | = 1,980.00 |
| Plain concrete | 89 cu. yds. @ $16.00 | = 1,424.00 |
| Mass of bases | 17 " @ $35.00 | = 595.00 |
| Total | = $5,954.00 |
Eye-Bar-Cable Structure
| Mayarí steel | 33,600 lbs. @ 10 ¢ | = $3,360.00 |
| Nickel steel | 13,800 " @ 11 ¢ | = 1,518.00 |
| Plain concrete | 100 cu. yds. @ $16.00 | = 1,600.00 |
| Mass of bases | 22 " @ $35.00 | = 770.00 |
| Total | = $7,248.00 |
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From these four estimates it is evident that at present prices untreated
Mayarí-steel eye-bar-cables cannot compete with wire cables in suspension
bridges. With the shortest economic span-length for highway suspension
bridges, viz., 1,000 feet, in order to compete with wire, the untreated
Mayarí steel would have to be put in place at a pound price of less than
9.2 cents. While this could probably be done without actual loss, it can
readily be seen that, in general, untreated Mayarí-steel eye-bars cannot
be employed economically for suspension-bridge cables.
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