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I. GENERAL DESCRIPTION.

11. The superstructure is divided into two parts: First, the ContinuousSuperstructure of the main bridge; Second, the Deck Span at the west end. 0■>'■ 2. The Continuous Superstructure will consist of a central span (resting on

Piers II and III), 621 feet inches long, from each end of which will projectda 1 cantilever arm, 169 feet 41 inches long; of an anchorage span (from theAnchorage Pier on the Tennessee shore to Pier I), 225 feet 10 inches long, fromi which will J project a cantilever arm precisely^ like those projecting from the■ central span; of two intermediate spans 451 feet 8 inches long (one of whichwill be suspended from the cantilever arms projecting from Piers I and II, and>the other will>be,suspended at the east end from the cantilever arm projecting-■from Pier III and will rest at the west end on Pier IV), the entire continuoussuperstructure being 2258 feet 4 inches long, divided into one span of 225 feet10 inches, one of 790 feet 5 inches and two of 621 feet 0J inches. ' ni * I; "'

,,--n 3. This Continuous Superstructure will be rigidly fastened to Piers I, III

and IV, but will rest on expansion rollers on Pier II. Slip joints will be pro-’ vided for expansion at the suspended ends of the independent spans.ieb[m4. The trusses will be placed 30 feet between centers and will be dividedinto panels 28 feet 2£ inches long, the right being reserved to shorten thepanels by an amount not exceeding one half inch at anjr time before the workis actually manufactured. 1 111

5. The Deck Span ! at the west end will be 338 feet 9 inches long from thecenter of Pier IV to the center of the pin on Pier V, divided into twelve panelsof 28 feet 12f‘inches each, the trusses being placed 22 feet between centers-JThe east end of the span will be carried in niches on the 1 west side of Pier IV;the west end will have roller bearings over the' 1 center of Pier V. This spanwill include a vertical bent which will carry the 1 west end of the west pair of-stringers.’ 11 b - -n '■ ’

yiiui 6;> The estimated approximate weight of the Continuous Superstructure is13 000 000 pounds ; that of the Deck Span 1 000 000 pounds, making the totalestimated weight of the superstructure of the bridge proper 14 000 000 pounds,ei ''(o// •-•-! i'' ■■ ‘o. • '■ 4 ! r .d'- t ■’ h: (<,

PLANS. - L " '

1- 7. Full detail plans showing all dimensions will be furnished by the

engineer. The work shall be built in all respects according to these plans.The contractor, however, will be expected to verify the correctness of the plansand will he required to make any changes in the work which are necessitated

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AEPENDIX L.

SPECIFICATIONS FOB STJPERSTBTJGTUKE.

by' errors J in these plans, without extra charge, where such errors could bediscovered by an inspection of the plans.

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II. MATERIAL.

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8. All parts, except nuts, swivels, clevises and wall-pedestal plates, will beof steel. The nuts, swivels and Revises -may be of wrought iron, but shallhave sufficient strength to break the bodies of the members to which they areattached. The pedestal plates will be of cast iron.

9. All material shall be subject to inspection at all times during its manu-facture, and the engineer and his inspectors shall be allowed free access to anyworks in which any-portion of the material is made. Timely notice shall be•given to the engineer so that inspectors may he on hand. m.;

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10. Steel will be divided into tllree classes: first, High Grade Steel, which

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shall be used in all the principal truss members; second, Medium $teel, which

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shall be used m the floor system, laterals, portals, transverse bracing and thelacing of the truss members; third, Soft Steel, which shall be used onlv forrivets and at the option of the contractor where wrought irpn is permitted.

11. The bolsters which carry the large pin bearings on Piers I, II and. Ill

shall be of cast steel. ‘ ‘ w

12. In any case where it seems doubtful what quality of steel is required,

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High Grade Steel shall be used.

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13. Steel maybe made by the open hearth or by the Bessemer process,but no steel shall be made at works which have not been in successful opera-tion for at least one year.

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14. All steel shall be made from uniform stock low ip phosphorus, and themanufacturer shall furnish reports of the analysis of every melt certified by-a

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chemist satisfactory to the Chief Engineer.

15. In the finished product of open hea,rth steel the arpount of phosphorus

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shall not average more than ^4^ of one per cent and never exceed A- of one per

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cent> . r : r., ;

16. In the finished product of Bessemer steel, the amount of phosphorus

shall not average more than of one per cent and never exceed A of one percent.

17. A sample bar three quarters of an inch in diameter shall be rolled

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from every melt, the method of obtaining the piece from which this bar is

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rolled to be the same in all cases, and the amount of work on this sample barto be as nearly as practicable the same as on the finished product. The firstlaboratory test shall be made on this sample bar in its natural sta(e witbp^tannealing.

rL 18. A.second sample bar having a cross section of one square inch shall be

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cut from the finished product of every melt. The second laboratory^eSjf ^^1be made on this sample bar in its natural state without annealing.

19. In the laboratory tests all observations as to elastic limit, ultimatestrength, elongation and reduction shall be made on a length of eight inches,

20. A piece of each sample bar shall be bent degrees, anfi closed up

against itself without showing any ( crack, or flaw on the outside of the bent

portion.

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21. The first laboratory test shall meet the following requirements;

Maximum Ultimate Strength, pounds per sq. inchMinimum “ “ “ •* “ iUJ

Elastic Limit, “ “ “

Percentage of Elongation in 8 inches“ “ Reduction at Fi-acture

grade Steel.

Medium Steel.

. 78 500

72 50Q

. 71500

65 500

, 42 000

38 000

. 20

24

. 40

45

Soft Steel.

63 00057 00032 0002850

22. The second laboratory test shall meet the following requirements:,.!J . 7 00 • • -it, Uf. - -

iMinimum

High Grade Steel.

Medium Steel.

Soft Steel.

h. ... 78 500

72 500

63 000

.... 69 000

64 000

55 000

.... 40 000

37 000.

30000

18

22

28

.... 38

44

50

Elastic Limit, “ “

Percentage of Elongation in 8 inches.-lot; 11 c “ Reduction at Fracture

23. If the ultimate strength comes within five hundred pounds of the maxi-

iJfinm pr miiumum limit, a second test will be made, and both tests will berequired to come within the limits. 1

24. Every melt which does not conform with these requirements shall be

rejected. .u

25. A full report of the laboratory tests shall be furnished certified by an

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inspector accepted by the Chief Engineer.

0I '-- 26/The broken and bent specimens shall be preserved subject to theorders of the Chief Engineer.

27. Three notices of the acceptance of each melt shall be mailed on theday of such acceptance, stating the number of the accepted melt and quality ofsteel. Two of these notices shall be sent to the Chief Engineer at his Chicagoand Ne^_ : Yoyk offices respectively and one to the shop inspector at theworks.