38

I

APPENDIX F.—Continued.

to provide can be settled most economically by putting it on the same floorwith the railroad; making this floor wide enough for two teams to pass, pro-viding a substantial railing on each side and excluding carriages, teams andanimals when trains are crossing. This arrangement is recommended only onthe score of economy, but as the highway travel will be exceedingly light it isnot thought that it will give you any serious trouble. I am not at all clear butwhat the requirements would be met by running a ferry train, but have notthought best to estimate on this. The total estimate shows that the cost ofa timber floor adapted to highway traffic, with railings, etc., will be $10 perfoot, or just double the cost of a roadway floor, besides which there will be theadditional 300 pounds per foot added to the dead weight of the bridge.

In the matter of approaches, the East Approach, which was formerly verysimple, being on the surface of the ground, is rendered much more troublesomeand expensive by raising the grade ten feet. The difficulties, however, willprincipally relate to street crossings and the purchase of the property, thegrade being generally about eight feet above the surface of the ground. As Iam unable to estimate the value of the real estate required for this approach,the entire cost has been placed, as you suggested, at $100 000.

The West Approach has, as before, been supposed to be built on a gradeof 11 per cent (66 feet per mile). The elevation of the top of the stringer atPier IV is 114, or 80 feet above extreme high water at the bridge site. I haveestimated on using an iron viaduct 4 800 feet long, the grade at the west endof it being 54, or 17 feet higher than the grade of your level track across thebottom land. West of this trestle the approach can be made in the form of anearth embankment and would connect with the present line of the Kansas City,Et. Scott & Memphis Railroad about two miles from the end of the viaduct.At present I should advise building this viaduct in spans of 30 feet, the con-struction being of the simplest possible kind. For foundations I have esti-mated on using small masonry piers four feet square at the smallest place, thetop of the masonry to be at the elevation of 39, resting on blocks of concretenine feet square, the bottom of the concrete being at elevation 24 and beingfarther supported by nine piles under each pier. The estimated cost of eachof these little piers, including iron anchor rods passing from concrete to top, is$285. When the piers are finished I should propose to fill around them to auniform elevation of 37, or two feet above high water, so as to protect the foun-dations, piles, etc., from the action of frost and water. This would amount tobuilding an embankment 40 feet wide and averaging perhaps eight feet highunder the whole of the trestle.

The roadway approach on the east side would amount to little. On thewest side, however, it will be necessary to rise from the level of the bottomland. It seems wise to do this in the cheapest possible way. This would beon a timber trestle, which, if built with a grade of six per cent., need not bemore than 1200 feet long, and its cost would not exceed $10 000.

On this basis the following estimate has been prepared of the cost of thebridge as now proposed, this estimate being as nearly as possible in the sameform as the estimate accompanying the report of February, 1887:

Pier I.

2 650 c. y. Masonry at $20..42 000 c. ft. Caisson “ 80 cts,84 000 “ Crib work “ 40 cts

Sinking.

Pier II.

5 400 c. y. Masonry at $20...81 000 c. ft. Caisson “ 80 cts141 750 “ Cribwork “ 40 cts,Sinking.

Pier III.

4 800 c. y. Masonry at $20..,72 000 c. ft. Caisson “ 80 cts,108 000 “ Cribwork “ 40 ctsSinking.

Pier IY.

2 100 c. y. Masonry at $20..31 200 c. ft. Caisson “ 80 cts78 000 “ Cribwork “ 40 ctsSinking.

$53 00033 60033 60015 000

$108 00064 80056 70040 000

$96 00057 60043 20025 000

$42 00024 96031 20010 000

Outfit for Foundation Work.

Protection Work, including Mats and Riprap of Piers II

and III, and Shore Protection at Piers I and IV.

Anchorage.....j.

Sloping and Finishing.

Total Substructure .. t.

$135 200

269 500

221 800

108 10050 000

100 00016 0002 000

11 000 000 lbs. steel at 6 cts.

2 200 ft. floor “$10.

Painting.

Total Superstructure

$660 00022 0006 000

Total Bridge Proper.

East Approach..

West Approach :

3 400 000 lbs. of iron at 5 cts.

320 Piers “ $285.

4 800 ft. floor " 5.

Painting..

75 000 c. y. Embankment at base.

Earthwork, 2 miles of road.

Total Approaches.

Highway Trestle on West side, 1200 ft. at $8Four miles of Track..

$170 00091 20024 0009 60015 00015 000

$100 000

324 800

Total Bridges and Approaches

Add 10$ for Contingencies.

Engineering.

$902 660

688 000$1 590 660

424 800

9 60020 000

$2 045 060

204 50650 000

$2 299 566

This estimate is $320186 more than the estimate of February, 1887, or,without providing for contingencies, $291 260 more.

Under the present plan the bridge proper reaches to the east anchorage, andits length includes the east approach viaduct of the former plan, so that the costof the bridge proper as now estimated is $31 860 more than the former estimate.

The former estimate was from the edge of the bluff at Memphis to the footof the grade on the west side of the river. The present estimate is from aconnection with the Kansas City, Fort Scott & Memphis Railroad track in

Fifth Street to a Connection with the same railroad on the west side of theriver, the present estimate including the following items which were not in the

former estimate:

East Approach.. $100 000

West Approach : Two miles of Earthwork. 15 000

Four miles of Track. 20 000

Total . $135 000

Add 10$ Contingencies.. 13 500

Total . $148 500

So that the cost of the bridge as now designed, including all allowances, is$171 686 more than the former estimate. This practically represents the addi-tional cost of the requirements which Congress and the Secretary of War nowinsist upon.

I have prepared a revised plan of the bridge which I expect to submitpersonally to the Secretary of War on Friday the 3d inst. A copy of thisplan accompanies this report. Of course you will not be ready to begin workuntil this plan has been formally approved, and it will then be too late to domuch work in the river this season. If, however, you have determined onbuilding the bridge, I would ask you to give us the, authority to put in thefoundation of Pier IY this year, and to purchase the steamer Bertram, nowfurnished with a complete pneumatic outfit, which has been used at Rulo andNebraska City Bridges. The total amount which would be expended for thisfoundation and the steamer would be less than $100 000. My idea would beto sink this foundation to the final depth and then sink a test pit within thecaisson (as was done at Rulo) and thus determine the character of the lowerclays on which the river piers are to be founded. The result of this examina-tion might lead to a very material saving in the cost of the river foundations,as this proved to be the case at Rulo.

If this authority is given, I should propose to do no other work atMemphis until 1889, but to prepare the plans of the two river piers with theutmost possible care, and to put in these two foundations during the low waterseason in the latter part of 1889. The foundation of Pier I could then be putin at any time and the masonry completed by the summer of 1890. Thecentral span (from Pier II to Pier III) should be erected during the low waterseason of 1890, and the remainder of the work would be independent of stagesof water. I should hope to open the bridge in the early part of 1891.

As to the conduct of the work, my present judgment is that it would notbe wise to put in any of the foundations by contract, as the contingencies (thatis, in the matter of cost) are so great that any contractor would feel obliged tomake his estimates on a basis which would leave him very large profits shouldeverything work well. After the completion of the foundation for Pier IY, itmay appear wise to do the work by contract, but my impression is otherwise.

All other parts of the work, including both masonry and superstructure.I should advise letting by contract. Yery respectfully yours,

Geo. S. Morison.