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paratively small. The section authorizes, on the recommendation of the Board of Engineers, such changes in the general requirements of this act as may be rendered necessary by the physical characteristics of the locality, or that can be made without injury to the interests of navigation. This proviso seems necessary, as otherwise the general requirements which in most cases would be sufficient might prohibit a bridge in some special locality where variation might be allowed without injury to any one, while in other cases such variations might be absolutely indispensable to the safety of navigation.

The section also requires the proper maintenance of both bridges and their accessory works. Experience has shown that these may be built in accordance with the requirements of law, but not so maintained and kept in repair as to prevent the unnecessary obstruction naturally resulting from letting various parts of the structures go to ruin.

Section 20.-This is a new section, based mainly on existing laws, and prescribes the mode of procedure in case of the failure of parties own. ing, controlling, or operating bridges to comply with the provisions of this act. The Board deem this a very important section and most neces. sary for protecting the interests of navigation.

Section 21 is essentially the same as the like numbered section in the original bill. There has been added a requirement in the case of low bridges for showing the stage of water, as is now done at most existing bridges, to the great advantage of the interests of navigation.

Section 22 is the same as the old section, with some minor changes in the wording.

Section 23 is unchanged from the original. Section 24.--A proviso has been added to the original section prohib. iting the reduction of head-room or channel-way by the constructions authorized in the section.

Section 25.—This is the first part of section 25 of the original bill. It has been slightly extended to make it more full and explicit, the additions being taken from existing laws. It also provides for the proper supervision of any work required under this section.

Section 26.—This is a new section, which provides for a general supervision of the construction of bridges by the Secretary of War, and for the prevention of unauthorized changes and deviations from the plans that have been properly approved. It also provides that, during construction, navigation at the bridge site shall not be restricted or interfered with to a greater extent than is absolutely necessary. The Board is of opinion that such a proviso is necessary in order to secure the execution of the provisions of this act, as without proper supervision the approved plans may be so deviated from in their execution as to affect injuriously the interests of navigation.

Section 27.- This is a new section, which fixes a time limit for the commencement and completion of work. Such a limit can work no hardship to parties actually intending to construct a bridge, and it is necessary in order to prevent the holders of a permission to build from using it for speculative or obstructive purposes.

Section 28.--This is a new section, repealing all former acts or parts of acts authorizing the construction of bridges within the limits cov. ered by this act, upon which construction has not actually begun. This action is considered absolutely necessary as there are now in ex: istence many such acts, some of them very old, and providing entirely inadequate protection for the navigation interests. This general act has been more carefully drawn than any previous special acts, and as its main object is to guaranty in the future the construction of properly

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designed bridges, it would be unjust to parties building under its provisons, and to the navigation interests as well, to allow an improper class of bridges to be built, under the provisions of some old charter not sufficiently guarded in its requirements. It is believed that in all the acts alluded to, the right to amend or appeal was expressly reserved by Congress.

Section 29.—This is the latter part of section 25, and contains the usual provision reserving the right to amend, alter, or repeal this act, and also to require the removal of any bridge constructed under its provisions, when the public interests so require.

The following papers are appended to this report: Copy of minutes of proceedings of the Board: Copy of bill as amended by the Board

The following papers referred to the Board for their information are herewith returned: Bill S. 275; copies of indorsements of the Chief of Engineers and of the War Department upon the subject; six printed copies of a proposed act authorizing the construction of bridges across

" the Missouri, Mississippi, and Illinois rivers, and prescribing the char. acter, location, and dimensions of the same," received from Mr. E. W. Gould, of the committee of the Merchants' Exchange of Saint Louis, Mo.. together with the reports of the officers to whom they were referred, and copies of letter of the Chief of Engineers, dated May 11, 1882, reporting upon a similar bill (S. 1679), and of amended bill submitted therewith, and also copy of Senate Ex. Doc. 20, Forty-ninth Congress, second session, containing report of the Board of Engineers relative to bridging the Mississippi River at or near Saint Louis, Mo. Very respectfully, your obedient servants,

Chas. R. SUTER,
Lieut. Col. of Engineers, U. S. A.

A. MACKENZIE,
Major of Engineers, U. S. A.

A. M. MILLER,
Major Corps of Engineers.

Tuo. H. HANDBURY,
Major of Engincers, U. S. A.

The undersigned, while agreeing fully with everything presented in the foregoing report, deem that some further remarks on the subject of bridging the Mississippi below the mouth of the Ohio are needed for a full understanding of the question involved.

The vast number of bridges erected in the last twenty years enables as to form a very definite opinion of the requirements as to site which are likely to be sought for. These are, first and foremost, small width of water-way and stability of banks and channel. For instance, no one would expect a bridge-builder to choose a site where the crossing of 10,000 feet of water-way would be required, when other sites having only from 2,000 feet to 3,000 feet of water-way were available. Yet this is just the choice which would be presented on the Lower Mississippi, and which narrows down the question of possible sites to a comparatively few and well-known localities. Furthermore, the nar. row places, being in the vicinity of bluffs or slowly-yielding banks, offer the additional advantage of comparative stability of both banks and channel, while the proximity of bluffs is an important factor in the question of approaches to a high bridge. At all places where the water-way is much in excess of 3,000 feet, unstable channels and caving banks are the rule; hence such sites would very likely be

prohibited, even if for any reason they should be chosen. Yet it is mainly in such localities only that places are found where tows could approach a bridge head on; the narrow places, being either in bends or between consecutive bends, invariably require flanking to a greater or less degree. It may further be stated that while the improvement of the river now in progress will undoubtedly increase the number of places where crossings can be made, yet, as the object of that improvement is to narrow the width at wide places to about 3,000 feet, and to preserve and encourage the curved shape of channel which can alone secure stability, it follows that such places will repeat the feat. ures now noted at points where the contraction is natural instead of artificial. Bridging the Lower Mississippi at any point will be a difficult and expensive operation, and the main cost will be for the piers. At all the narrow places alluded to depths at high water of from 130 feet to over 200 feet will be found. The numerous borings made along the river from Cairo to Lake Providence, although carried far below the present river bed, failed to develop the presence of rock, or any material which could be certainly depended on for a safe foundation. It is still a matter of great uncertainty to what depth below the apparent bottom scour or movement of some kind may extend, especially in the presence of artificial obstructions like the piers of a bridge. But that some such action as this must be expected and provided against is certain, so that to reach the height prescribed, of 70 feet above high water, piers exceeding 300 feet in height will probably be required, with foundations proportionately broad and massive to insure stability. The building of such structures will be both difficult and expensive, and when these facts are understood by prospective bridge-builders, their choice will probably incline to much longer spans than the navigation interests are likely to demand. It seems to be the general opinion that the economic limit of length for the truss-spans now so generally used lies between 600 and 700 feet. For wider spans other forms of construction must be used, of which the cantalever and suspension may be taken as types. Of these there exist already ex. amples of great length of span and others are projected. The Forth bridge in Scotland of the cantalever type has a clear span of 1,700 feet and head-room of 150 feet. Another cantalever bridge proposed for crossing the St. Lawrence at Quebec has a clear span of 1,442 feet and head-room of 150 feet. The New York and Broooklyn Suspension Bridge has a clear span of 1,600 feet and head-room of 135 feet, while a railway suspension bridge across the Hudson is projected with a main span of 2,850 feet and 150 feet head-room.

CHAS. R. SUTER, Lieut. Col. of Engineers, U. S. A.

A. M. MILLER,

Major Corps of Engineers. The CHIEF OF ENGINEERS, U.S. A.

A BILL to authorize the construction of bridges across the Missouri River between its mouth and the mouth of the Dakota or James River; and across the Mississippi River between the mouth of the Minnesota River, in the State of Minnesota, and the port of Natchez, in the State of Mississippi; and across the Illinois and Des Plaines Rivers between the mouth of the Illinois and the city of Juliet, in the State of Illinois; and to prescribe the character, location, and dimensions of the

same.

SECTION 1. Be it enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That any persons or corporations, having lawful authority, may hereafter, when public necessity so demands, erect bridges at points

where said construction will not materially affect the interests of navigation across tbe Missouri River between its mouth and the mouth of the Dakota or James River; and across the Mississippi River between the mouth of the Minnesota River and Natchez, Mississippi; and across the Illinois and Des Plaines Rivers between the mouth of the Illinois and the city of Joliet, in the State of Ilinois, for railroad or other uses upon compliance with the provisions and requirenients of this act; and hereafter no bridge shall be built over said rivers within said limits except under the said provisions and requirements.

SEC. 2. That the sections of this act numbered one, two, three, four, five, six, seven, eight, nine, ten, nineteen, twenty, twenty-one, twenty-two, twenty-three, twentyfour, twenty-five, twenty-six, twenty-seven, twenty-eight, and twenty-nine shall be general, and shall apply to all bridges authorized under this law; and that the sections pumbered eleven, twelve, thirteen, fourteen, tifteen, sixteen, seventeen, and eighteen shall apply specifically to bridges at such points on the Mississippi, Missouri, Illinois, and Des Plaines Rivers as are covered by the sections enumerated,

SEC. 3. That whenever the phrases “bigh-water mak,” “medium stage of water," or “low-water mark” are used in this act they shall be held to mean the local high water, medium stage, or lowest water-level at the bridge site as determined by the Secretary of War; and wherever, the phrase "clear head-room" is used it shall be held to mean the clear height measured from the water-surface to the lowest part of tbe superstructure in any span; and wherever the phrase "clear channel-way” is used it shall be held to mean the clear width of openings at the elevation of low water but measured in a direction at right angles to the current of the river at that stage of water which is most important to navigation; and wherever the phrase " length of span” is used it shall be held to mean the distance between centers of adjacent piers measured on the center line of the bridge; and wherever the phrase

high bridge” is nsed it shall be held to mean a bridge of which the spans over navigable channels are high enough to permit the passage of boats under them at all stages of water; and the phrase "low bridge” shall be held to mean a bridge bav. ing an opening or openings through which boats can pass at all stages of water.

SEC. 4. That in all bigh bridges authorized by this act, except as hereinafter pro. vided, every span over the water way between the shore lines of the river at a bankfull stage shall give a clear head-room not less than that prescribed for those over the channel-ways; also that in such high bridges one or more wide or channel spans, of lengths to be hereinafter prescribed, shall be placed over the main channel or chaunels of the river; and in case the channel is variable the number of chanuel-spans shall be increased so that there may be a good navigable passage for all classes of boats under some parts of the bridge at all stages of water.

SEC. 5. That all low bridges authorized under this act shall be so located that a good channel can be kept and maintained for the passage of boats at all navigablo stages of water, and that the said channel shall be made easily accessible by boats at all such stages; and that the draw opening or openings shall be located over the above specified channel in such a manner that one or all of the openings can be conveniently and safely reached by boats at all navigable stages of water; and that one draw-opening at least shall be over the best and most convenient channel of the river, at any stage of water; and said draw-opening shall be visible from all parts of the channel for a distance of not less than one mile above said opening; and wherever practicable and in the interests of navigation, all bridges located in the vicinity of important landings shall be placed above rather than below said landings; and that in all bridges with channel or raft spans or draw-openings of less than three hundred feet clear channel-way authorized by this act, there may be required, as a part of the necessary accessory works provided for in this act, one or more protection-piers of masonry, crib-work, or piling, as may be directed by the Secretary of War, extending from the end or ends of such spans or openings up-stream for a distance of one thousand feet or less from the center-line of the bridge, and which protection pier or piers shall be properly arranged with ring-bolts, cavils, snubbing-posts, or similar accessories, and fender.planking, so as to enable boats or rafts to tie up alongside and drop down through the draw-openings, channel, or raft-spans, at such times as it may be dangerous to attempt the passage of the same when under beadway; and in addition to the said protection pier or piers, the Secretary of War may also require as a part of said accessory works, when a draw-opening or raft-span is near shore, that the end of the opening or span be connected with the shore by a substantial gnard-fence, extending up-stream in such direction and to such distance as will render access to the said draw-opening or raft-span easy and safe at all times; and also that if, by reason of the location of a bridge in or near a city harbor, or from any other cause, the draw opening, channel, or raft-span next the shore becomes difficult of access at any season or seasons, because of the proximity of river craft, which are or may be tied up to the bank, or from any other canse, then the company or persons owning, controlling, or operating said bridge shall, by purchase or otherwise, ex

ENG 88—150

tinguish the right to obstruct the entrance to said draw-opening or span for a distance of at least seven hundred feet above and seven hundred feet below the bridge.

SEC. 6. That all draw-spans authorized by this act shall be operated by steam or other reliable mechanical power, and shall be opened promptly upon reasonable sigpal for the passage of boats, except when trains are passing over said span or spans; but in no case shall unnecessary delay occur in opening said draw after the passage of trains; and also, that in case the opening of a draw is delayed by reason of the passing of a train after the signal has been given from a boat ready to pass through, the draw shall be opened for the passage of such boat before another train is allowed to pass over the said span or spans; nor shall there be any unnecessary delay in the passage of trains over the bridge.

SEC. 7. That all piers shall be built parallel with the current of the river at that stage of water which is most important for navigation; and the bridge itself shall ve built as nearly as may be at right angles thereto; and that riprapping or other protection for imperfect foundations which will lessen the required water-way sball not be permitted; also that piers which will produce cross-currents or bars dangerous to navigation shall not be constructed; and if after construction any piers or accessory works are found to produce the above-mentioned effects, or if any riprapping or other protection prohibited by this section is found to exist, the nuisance shall be abated or corrected under the direction of the Secretary of War or at the expense of the company or persons owning, controlling, or operating said bridge.

Sec. 8. That, in the case of all bridges built under the provisions of this act, the approaches to the bridge shall be so designed and constructed as not to interfere with the free discharge of the river in seasons of flood; and any encroachment on the highwater cross-section by piers, solid embankments, or otherwise, which will result in unduly accelerating the high-water current at the site of the bridge shall not be allowed.

Sxc. 9. That, if the interests of navigation so require, the clear channel-ways of any proposed bridge located in the immediate vicinity of an existing bridge may be made to correspond in length and location of spans to the clear channel-spans of said existing bridge.

Sec. 10, Tbat any persons or company constructing any bridge under anthority of this act shall build and maintain at all times as accessory works to such bridge, such booms, piers, dikes, guard fences, and similar devices as may be necessary to insure at all times a permanent channel for a sufficient distance above and below the bridge site, and for the guiding of rafts, steam-boats, and other water craft safely under or through said bridge; and if at any time after the construction of the bridge and its accessory works the approaches to draw openings, channel-spans, or raft passages in bridges over the navigable waters referred to in this act are found to be dangerous or difficult of access by any important class of river traibic, the Secretary of War may, upon the recommendation of the Chief of Engineers, United States Arniy, order the company or persons owning, controlling, or operating said bridge to construct under his direction, and to maintain, such additional sheer-boons, dikes, and other devices as will obviate the difficulty mentioned, which additional sleer-booms, dikes, aud other devices shall be built and maintained at their own expense by said company or persons.

Sec. 11. That all bridges anthorized by this act over the Missouri River abore the mouth of the Platte River shall be high bridges with unbroken and continuons spans, all spans over the water-way to have a clear channel.way of not less thau tbree hun. dred feet, and a clear head-room of not less than fifty feet above high-water mark.

Sec. 12. That all bridges authorized by this act over the Missouri River below the mouth of the Platte River and above the mouth of the Kaw River, shall be high bridges with unbroken and continuous spans, having at least one channel-span of not less than four hundred feet clear channel-way, all other spans over the water-way to have a clear channel-way of not less than three hundred feet; and all said spans shall have a clear head-room of not less than fifty feet above high-water mark.

Sec. 13. That all bridges authorized by this act over the Missouri River between its mouth and the mouth of the Kaw River shall be high bridges with unbroken and continuous spans, all spans over the water way to have a clear channel-way of not less than four hundred feet, and a clear head-room of not less than fifty-five feet above high-water mark.

Sec. 14. That all high bridges over the Mississippi River above the month of the Missouri, and over tho Illinois and Des Plaines Rivers, authorized by this act, sladil have one or more channel-spans, each having not less than three hundred and titty feet clear channel-way, and not less than fifty-five feet clear head-room above highwater mark, and the clear head-room under other than channel-spans may be less than fifty-five feet: Provided, That no part of the superstructure of such spans slali give a less head-room than ten feet above high-water mark: And prorided further. That the interests of navigation be not injured by such reduction in height. That all low bridges within the above-inentioned limits shall have two or more draw-open

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