The plan attached hereto shows the character of the undertaking. The new channel is nearly 9½ miles in length. It starts from Nussdorf at the foot of the well-known hill called the Kahlenberg, and passes through the flat lands of the Prater, or great public park of Vienna, with a slight curve towards the city, in order that the navigable channel, holding generally to the outside of the curve, should be nearest Vienna, and as close to it as possible, thereby facilitating the shipping on the quays.
Plan of Danube Improvement Works.
Danube Improvement Works.
The Locks of Nussdorf.—To prevent winter accumulations of ice from entering the new canal, and to divert floods, locks were constructed at Nussdorf, which are indicated in the drawings herewith. The side walls are founded on cylinders sunk down to the gravel to a depth of 31 feet below zero, and the tops of the abutment of the lock are 15 feet 6 inches above the same level. The distance between the side walls is 155 feet 10 inches. The entrance to the lock is closed by a caisson, the lock being closed only in winter. The invert of the lock is of béton, set in Portland cement, 4 feet 1½ inch thick, the foundation being of piles, as shown on the plan. The level of this invert is 12 feet 9 inches below zero; below that part of the invert, at the entrance to the lock, the floor is made of heavy stonework laid at the same level. The foundations of the barrage at Nussdorf consist of iron caissons, that on the right bank being rectangular in form, and 81 feet long by 18 feet 7 inches wide, while the wall on the left bank is 99 feet long, by the same width as the other, with an enlargement on the side towards the canal for the lock gates.
Joining the old bed of the Danube at the Bridge of Stadlau, and following its course as far as the island of Wiedenhaufen, through which it passes, the channel line enters the river again opposite the village of Albern. On the left side of the river a protecting dyke was erected in order to guard against flooding the great plains of Marchfeld.
The new channel is 933 feet wide, 8·3 to 11·4 feet in depth, and has a mean slope of 1 in 2272, the speed of the current varying according to the state of the river. The side slope has an inclination of 2 to 1, and is riveted throughout in stone 9¾ inch thick, with a banquette on the top 39 inches wide. The ground on the right bank has been raised so as to reach the same height as the dyke on the left, thus protecting the country round about from inundation.
The above works cost over two millions sterling. The quay walls, locks, and other operations were described in a monograph published in 1878 by M. Hersent, one of the contractors, and reprinted in Engineering, from which the foregoing particulars have been mainly reproduced. The total amount of earthwork was 23,575,928 cubic yards, divided as follows:—