Democratic Sentinel, Volume 14, Number 36, Rensselaer, Jasper County, 3 October 1890 — MICHIGAN AND CANADA [ARTICLE+ILLUSTRATION]

MICHIGAN AND CANADA

UNITED BY AN AVENUE UNDER THE ST. CLAIR RIVER. Completion of tlie Longest Hirer Tnmel In the World—Breaking the Tunneling Record—Progress at the Kate of 159 Feet a Week—lllustration's of Some Marvelous Machinery In Operation.

HE great railroad tunnel at IPort Huron, Mich., is practically completed, and trains 'will be running through it by the end of the year. The United States is now connected with Canada by an avenue under the St. Clair liiver. It is in several respects the most notable and

successful engineering feat of its kind on record. It is the longest river tunnel in the world, being 6,050 feet in ail, 2,300 feet of which is under the river bed. Its outside diameter is 21 feet. It is the first cast-iron tunnel of its kind. It lias been constructed at an unprecedented rate. Its prosecution has been attended with fewer casualties than any other similar \\;ork, one broken leg being the extent of the accidents, excepting two deaths of workmen indirectly due to disregard of tlie company's orders regulating the use of air pressure. What is perhaps yet more remarkable, the cost of its construction will -come within the first estimate of three million dollars. It is a little more than one year since the tunnel proper was begun, the steel shields having been lowered down inclines into the cuttings in August, 1889. Work on the cuttings, however, was begun in January, 1889, and test shafts

were sunk on both sides of the river in 1887. The St. Clair Tunnel Company was formed in the year 1880. This great work became a necessity by reason of the growth of traffic over the Grand Trunk Railway of Canada, the Chicago and Grand Trunk, the Detroit, Grand Haven and Milwaukee, and the Toledo, Saginaw and Muskegon Railroads. The steam car ferry now in operation at this point was found inadequate and also unreliable during a portion of the year by reason of the power of the currents (eight miles an hour; and the ice in the river. A bridge was impracticable, owing to the low level of both shores and the great amount of shipping traffic of large dimensions. The walls of the tunnel, as indicated in our smallest illustration, are formed of thirteen cast-iron segments and a key. These segments are cast with thirty-two holes in them, twelve in each side flange and four in each end. The inside diameter of the tunnel is twenty feet. The idea of substituting these segments for brick work was suggested by Mr. Joseph Hobson, of Hamilton, Out., the chief engineer of the St. Clair Tunnel Company, and also chief engineer of the Great Western Division of tho Grand Trunk Railway. Mr. Thomas Murphy, of New York, was the superintendent of excavation. The mechanical department on both sides of the river is under the charge of Mr. J. T. Eaines, the engineer who invented the apparatus for lowering the stupendous shields into their place, and also a system of cocks on the twenty-four hydraulic jacks surrounding the shield, whereby two men can do the work of twenty-four. By the simple opening of a valve, the direction of the shield could be shifted as to follow the engineer’s level. Sir Joseph Hickson at a meeting of the directors some time since expressed the conviction that the tunnel would be completed for traffic within eighteen months. The subsequent rate of progress has so far exceeded the most sanguine expectations and has so c ompletely beaten the record of all former similar works that the talk now is that the traveling public may be inspecting the interior of this tunnel by the end of the year. The shield to which tho singular security as well as the rapidity of this piece of tunneling is due is the invention of Mr. Alfr.ed E. Beach, of New Y T ork. The mode of operating this piece of machinery, which has revolutionized the art of river tunneling, is graphically

portrayed by the main illustfation accompanying this description. The shield which is operated simultaneously from each end of the tunneling, consists of a strong cylinder somewhat resembling a huge barrel with both heads removed. The front end of the cylinder is sharpened, so as to have a cutting edge to enter the earth. The rear end of the cylinder for a length of two feet or so is made quite thin and is called the hood. Arranged around the main walls of the cylinder and longitudinal therewith are a series of hydraulic jacks, all operated from a common pump, each jack having cooks whereby it may be cut off from the pump whenever desired. Within the shields are vertical and horizontal braces and shelves. W T hen at work the iron plates or the masonry of which the tunnel is composed are first built up within the thin hood of the shield; the hydraulic jacks are then made to press against the end of the tunnel plates or masonry, which has the effect to push the shield ahead into the earth for a distance equal to the length of the pistons of the jacks, say two feet or not quite the length of the hood, and as the shield advances men employed in (the

front of the shield dig out and carry back the earth through the shield. By the advance of the shield, the hood, within which the iron or masonry tunnel is built, is drawn partly off from and ahead of the constructed tunnel, thus leaving the hood empty. The pistons of the hydraulic jacks aTe then shoved back into their cylinders, and a new section of tunnel is built up within the hood as before described. The shield is then pushed ahead, and so on. The extreme end of the tunnel is always within and covered and protected by tire howl. In this manner the earth is rapidly excavated or bored out and the tunnel built without disturbing the surface of the ground. Eacli shield is circular, 21 feet 7 inches in diameter, 16 feet long, and is built ol plate steel one inch thick. It is divided into twelve compartments by means oi two liorizontal and three vertical stays, which are built up to a thickness of twe inches. These stays have a knife esJg( in front and extend back ten feet, leaving six feet of clear cylinder,’into which the end of the tunnel extends. Ten oi the compartments are permanently closed and bracings of angle iron placed across them. The other two are provided with heavy iron doors, which can be closed at once in case of accident oi danger. These doors are situated at the bottom in the center, and through them is passed all the excavated matter. Flush with this heading (with their cylinders extending forward into the compartments) are twenty-four hydraulic rams at equal distances around the shield. These rams are eight inches in diameter and have a stroke of twentyfour inches. The profile illustration will give a popular understanding of the proportions of the different sections of thil

tunnel, of the difficulties overcome in its completion and of the magnitude of the work. From the American euttiqg to the river’s edge is 1.800 feet; from the Canadian cutting, 1,950 feet; under the river, 2,300. The subterranean approaches will be on the Canadian side 13,000 feet, on the Michigan side 9,000 feet. For the tunnel proper 2,196,400 feet of soil have been excavated. The east iron lining lias required 55,962,500 pounds. There have been used in securing this lining 859,242 bolts. The tunnel will drain itself of the surface water entering by the approaches

into an intercepting tunnel or vertical shaft 122 feet in depth, extending to bed rock, which is reached at that point. This well will by the highest pumping engine of its kind in existence. It will be over one hundred feet in height. The pump of the engine will be on the bottom of the tunnel, while the' cylinders will be on the level of the ground. The tunnel at present is dirty with clay and silt, admitted during the work of excavation. After being cleaned it is to be treated with a preparation to prevent rusting. The lower third of the tube is to bo lined with brick and cement 1o

prevent deterioration of the casing by the brine that leaks from meat ears. One railway track will be planked on both sides. The ties will be of iron, conforming in their curve to the bottom of the tunnel. Coke engines will be used for motive power, in order to avoid as much as possible gas and smoke. An electric light station will be maintained on the Port Huron side, and the tunnel will be at all times as light as day. As soon as the present tunnel Is in running order another alongside of it will be begun, using the same machinery, with the exception of tho shells of the pair of shields, which it was impossible to remove.

LONGITUDINAL SECTION OF THE TUNNEL.

ENTRANCE OF THE TUNNEL.

WORKING IN THE TUNNEL.