Page images
PDF
EPUB

that now finds its way down the river by that route will be forced into the Virginia Channel. The capacity of the latter must, therefore, be increased. This is now being done above the bridge, and it will be done below it, by dredging. To secure the required area of cross section through the bridge would require dredging to be done between the piers, which, it is believed, is not practicable to the extent required without endangering the structure.

The best and only satisfactory way of correcting the defects of this bridge is to build a new one several feet higher, on fewer piers, with wider spans. The piers should be set as nearly as practicable in the axis of the freshet current, and should rest on the rock or hard-pan, which it is believed will be found to underlie the softer strata of mud. In any case, the body of each pier should extend to a depth below the surface of the water equal to the ruling depth of water above and below the bridge.

No riprap protection should be allowed around the piers to reach a level above that of the general bottom of the river channel in the neighborhood of the bridge.

Very respectfully, your obedient servant,

To the CHIEF OF ENGINEERS, U. S. A.

PETER C. HAINS,
Major of Engineers.

(2) POTOMAC AQUEDUCT.

UNITED STATES ENGINEER OFFICE,
Washington, D. C., November 5, 1884.

SIR: In accordance with General Orders No. 13, current series, Headquarters Corps of Engineers, United States Army, I have to report that the bridge known as the "Aqueduct," that spans the Potomac River between Georgetown, D. C., and the Virginia shore, is an obstacle to the free and safe navigation of the Potomac River.

The bridge is an acqueduct for the Washington and Alexandria Canal, which is here carried across the Potomac River.

The piers of the bridge are built of stone, the superstructure being of wood. There is ample width between the piers for the largest vessels that come to Georgetown to pass, and the depth of water is over 20 feet at low tide.

At mean high tide there is only a clear space of 25 feet between the timber supports of the lower chords of the truss and the surface of the water. As a consequence, none but the smallest of steam-boats can pass under it, and practically it renders navigation above the bridge impracticable for anything but small tugs and flat-boats.

Paragraph 2550, Revised Statutes, provides that the collection district of Georgetown shall extend to the head of the navigable waters of the Potomac River, which is near Little Falls. Between the latter place and the Aqueduct Bridge, a distance of more than 3 miles, there exists a deep, navigable channel, obstructed only at two places by shoals, which have over them a depth of 16 and 19 feet, respectively, at mean high tide. On the Georgetown side of the river there is over 19 feet at high tide for a distance of 3,000 feet above the bridge.

In a commercial point of view, that part of the river would be of great value if the way to it was not barred by this bridge.

It is an obstruction in another respect. The piers, abutments, and causeway reduce the width of the river from about 1,600 feet, its natural width between the lines of high water, to about 950 feet. This re

duction causes an abnormal rise in the surface of the water in times of freshets.

The bridge can best be altered so as not to interfere with the free and safe navigation of the river by discontinuing its use as an aqueduct, and providing a draw through which vessels can pass. This would necessitate the entire rebuilding of the superstructure, and the modification of one of the abutment piers to serve as a draw-pier.

Other interests may be involved in such a change, but a discussion of them is beyond the province of this report. The bridge interferes with the free and safe navigation of what would doubtless become a very important part of the river were it not there, and the only satisfactory way of removing this interference is to dispense with the aqueduct por tion and rebuild the superstructure as a highway bridge, with a suita ble draw for the accommodation of vessels of the largest class that visit Georgetown.

Very respectfully, your obedient servant,

To the CHIEF OF ENGINEERS, U. S. A.

PETER C. HAINS,
Major of Engineers.

REPORT OF CAPTAIN F. A. HINMAN, CORPS OF ENGINEERS.

UNITED STATES ENGINEER OFFICE,

Norfolk, Va., October 31, 1884.

GENERAL: In accordance with General Order No. 12, Headquarters Corps of Engineers, U. S. Army, current series, relative to sections. and 8 of the act of July 5, 1884, making appropriations for the construc tion, repair, and preservation of certain public works on rivers and har bors, and for other purposes, I have the honor to submit the followin final report on all the matters known to me in this district covered b the foregoing:

The following bridges are considered obstructions to the free navig tion of the waters that they cross, for the reasons specified below, viz The Norfolk and Western Railroad bridges over the Eastern and Southern branches of the Elizabeth River (shown on the accompanying map*) and the wagon bridge over Town Creek, North Carolina, 33 miles above its mouth. Each will now be referred to in detail.

(1) The Norfolk and Western Railroad Bridge over the Eastern branc of the Elizabeth River.--The present draw-opening is at the extreme north ern end of the bridge at the right bank. It is 40 feet in the clear, and has a depth through it of 13 feet at mean low water. The approaches to this draw are as follows: The upper approach is very crooked and shallow from the main channel to the draw-opening. On a line perpendicular to the draw-opening, and about 300 feet above it, is a shoal with but 13 feet of water on it at mean low tide. The lower approach bas been lately dredged by the United States, and, so far as depth is con cerned, is satisfactory. The draw-opening should be at least 50 feet wide, and placed near the middle of the stream, where the deep chan nel is, between the piers marked A and B, with suitable guide-piles above and below for safety of navigation through it.

(2) The Norfolk and Western Railroad Bridge over the Southern brand of the Elizabeth River.-The river at this point has been contracted by

* Map omitted.

earthen causeways, terminating in masonry bridge abutments on either side, that on the east side being 88 feet long and that on the west side 256 feet in length. The present draw-opening is at the extreme eastern end of the bridge, is 40 feet, in the clear, and has a depth through it of 8 feet at mean low water. The approaches to this draw are on a curve, and hard for vessels, particularly those with tows, to make, especially when the wind blows from certain quarters.

I quote as follows, relative to this bridge, from report dated January 30, 1872, of the late Capt. C. B. Phillips, Corps of Engineers, found in report of the Chief of Enginers, 1872, page 719:

Below the lock of the Dismal Swamp Canal no difficulty is experienced in the navigation of the Elizabeth River. A deep and unobstructed channel exists up to this point and, in fact, to a point about 2 miles farther up the river.

The above remark should be qualified by stating that the Norfolk and Petersburgh Railroad Bridge, which crosses the river about threefourths of a mile above the Dismal Swamp Lock, causes considerable annoyance to shipping, much of which is taken up and down the river in long tows. As many as five schooners sometimes constitute a single tow.

The draw of the bridge referred to is badly located. It is nearly over to the right bank of the river, away from the deepest water, and out of the course which shipping would take were it not for the bridge. This evil, however, it appears must continue to exist, as litigation has, I understand, failed to correct the matter.

(The Norfolk and Petersburgh Railroad is now a part of the Norfolk and Western Railroad.)

The draw-opening should be at least 60 feet wide, and placed near the middle of the stream, where the deep channel is, between the piers marked C and D, with suitable guide-piles above and below, for safety of navigation through it.

(3) Bridge over Town Creek, North Carolina.-I quote as follows regarding this bridge, from report dated August 4, 1884, of the late Mr. W. H. James, assistant engineer:

Town Creek, North Carolina, for the improvement of which $1,000 was appropriated by act approved July 6, 1881, and expended under my charge, for an account of which work reference is respectfully made to Appendix K 17, of the Annual Report of the Chief of Engineers for 1883, is obstructed 34 miles above its mouth, on the west side of the Cape Fear River, 8 miles below Wilmington, by a common county-road bridge, belonging to the county of Brunswick, North Carolina. This bridge has no draw. The creek is navigable for the improved distance of 19 miles from its mouth for small steam-launches drawing not over 34 feet of water. These boats, in passing under the bridge, have to lower their smoke-stacks, and, for want of a draw, none but very small, low boats can pass at all. I am informed that if compelled to put in a draw or abandon the bridge, the county would probably remove it and close the road.

It is manifest that there should be either a proper draw-opening in this bridge or else it should be removed.

It is believed that the southern abutment or causeway (shown on accompanying map*) to the county bridge that formerly crossed the eastern branch of the Elizabeth River interferes with the free and safe navigation of said river to the extent described below, for which reasons the structure should be removed.

*Map omitted.

In my communication to you of the 1st ultimo, relative to Norfolk Harbor, I stated as follows in regard to this:

[ocr errors][merged small]

It is thought that the shoaling at the mouth of Eastern Branch is very largely due to natural causes that will always exist, aided heretofore by the county bridge, a part of which has been removed, as stated, leaving the southern abutment, which should al be removed. There are no means of ascertaining the amount of deterioration du specifically to this bridge.

I also quoted in said communication from reports as follows:

1. Report dated January 30, 1872, of the late Capt. C. B. Phillips. Corps of Engineers (Report of the Chief of Engineers, 1872, page 722;

[blocks in formation]

We find slight and rather peculiar changes in the bed of the harbor between the county bridge across the Eastern Branch and the confluence of the two branches. W find a slight tendency of the channel to deepen immediately and for some little distance below the bridge.

Further down (some 800 yards below the bridge) shoaler water, which, as far as is known, has always existed, is encountered, and continues until the infinence of the Southern Branch is felt. The depth of the shoaler water referred to has changed bu little since the soundings were taken by the Coast Survey. It appears to have filled in very slightly. Its worst feature seems to be that the shoal is slowly extending along to the wharves immediately below the ferry. I attribute these changes to the existence of the county bridge across the Eastern Branch. The stream is consider ably contracted at this point by a long causeway, which constitutes the southern extremity of the bridge.

This accounts, in my opinion, for the slight deepening immediately below the bridge, and also for the slight additional shoaling below, the removed material being deposited as soon as the wider portion of the stream is reached.

It will be perceived that a considerable deepening has taken place immediately a the confluence of the two branches. This would seem to be but the mere result of the changes just referred to, the gradual extension of the sboaler water near the ferry seeming to contract the width of the Southern Branch channel, and causing it to mak deeper water. From this point on towards the entrance of the harbor, and also i following up the course of the Southern Branch, the water in the channel seems have pretty generally maintained its original depth.

[blocks in formation]

2. Report dated February 15, 1875, of Mr. S. T. Abert, United States civil engineer (Report of the Chief of Engineers, 1875, Part II, pages 146-147).

The bar which occupies the main channel is partly due to the county bridge, yards above.

*

This bridge is owned by private parties, who, I have been informed, are willing to sell it, and the city authorities have taken the preliminary steps for its purchase and removal. In order to benefit the harbor to the fullest extent, the causeway should be removed at the same time as the bridge.

*

*

Very respectfully, your obedient servant,

F. A. HINMAN, Captain of Engineers.

The CHIEF OF ENGINEERS, U. S. A.

REPORT OF CAPTAIN W. H. BIXBY, CORPS OF ENGINEERS.

UNITED STATES ENGINEER Office,

Wilmington, N. C., January 15, 1885.

SIR: In accordance with the instructions of General Orders, No. 13, Headquarters Corps of Engineers, United States Army, Washington,

**

D. C., 23d July, 1884, I have to submit, berewith inclosed, my final eport upon the bridges, etc., referred to in sectious 2 and 8 of the river and harbor act of July 5, 1884. Very respectfully, your obedient servant,

The CHIEF OF ENGINEERS, U. S. A.

W. H. BIXBY, Captain of Engineers.

FINAL REPORT UNDER SECTIONS 2 AND 8 OF THE ACT OF JULY 5, 1884, MAKING APPROPRIATION FOR THE CONSTRUCTION, REPAIR, AND PRESERVATION OF CERTAIN PUBLIC WORKS ON RIVERS AND HARBORS, AND FOR OTHER PURPOSES.

NEUSE RIVER, NORTH CAROLINA (UNDER IMPROVEMENT).

Near Kinston this river is crossed by the Atlantic and North Caroina Railroad on a draw-bridge, whose draw-span is placed upon the shallow side of the river, instead of over the main channel-way. The present improvement will probably be so far finished in 1886 as to permit of a deeper navigation above this bridge at Kinston than will Then be able to pass through this draw-opening. All the steamer capcains whom I have so far heard from state that they have not as yet been delayed from want of water at this draw-opening, and I do not see any reasou for a change in the position of a draw before 1886. I therefore recommend that this draw may be permitted to remain in its present position for the present, but that it be moved to the channel side of the river as soon as it becomes the chief serious obstruction to permanently increased depth of navigation between New Berne and Kinston.

Near Goldsborough this river is crossed by the Wilmington and Wellon Railroad, on a single-span bridge, without a draw. The bottom of the bridge is about 17 feet above low water. The channel is said to be partially obstructed by a pier of the former bridge. Very few steamers have so far reached this bridge, although the river is navigable for several miles above Goldsborough. I therefore recommend that this bridge be permitted, for the present, to remain in its present condition, provided that the owners will clear away the obstructing portion of the old pier beneath.

Above Goldsborough, and below Smithfield, there are six county bridges, without draws, but there has as yet been no navigation denanding draws. When needed, the draws will undoubtedly be put in by the county authorities. I therefore recommend that these bridges be permitted, for the present, to remain in their present condition, provided that their owners will insert draws therein whenever needed by the

Steamers.

As far as I know, these eight are the only bridges below the head of resent navigation which obstruct the navigation of the Neuse River.

TRENT RIVER, NORTH CAROLINA (UNDER IMPROVEMENT).

As far as I know, there are no bridges below Trenton, the head of present navigation, that obstruct the navigation of the Trent River. ENG 88-160

« PreviousContinue »