Lifting A Railway Bridge.

No undertaking in our day is apparently too big to be carried through successfully by the engineer. Whether it be the construction of a great ship canal, the boring of a tunnel a dozen miles through a mountain, shifting a skyscraper intact to a new site, or building flying machines of a speed capacity of 300 miles per hour, the engineer is the man responsible for these wonderful achievements.

An engineering feat surpassing in magnitude anything of the kind previously attempted in the Southern Hemisphere, and one of considerable interest to railwaymen, was recently satisfactorily carried out at Kafue, in Northern Rhodesia, some 2,000 miles from Cape Town.

In order to protect the Kafue Railway Bridge from the floods which threatened its safety every year it was decided to raise the entire structure -1,398 feet in length and weighing 910 tons-five feet above the foundations on which it had rested for twenty years. The bridge consists of thirteen spans and is one of the longest in Africa. Twenty-eight hydraulic jacks (placed in position under saddling girders which joined the spans together) were employed to lift the bridge. Each jack was manned by two natives under the guidance of a European. At a given signal the huge bridge was raised to the required height in individual lifts of ten inches. Great wooden wedges were employed to take the weight off the jacks after each lift, these being removed after a concrete block had been cemented in position on each pier. The lifting operations were so arranged that traffic was able to pass over the bridge after each lift of ten inches had been completed-the permanent way being raised the required distance for this purpose.

The work was carried out under the direction of Mr. Rigley, the bridge engineer of the Beire Mashonaland and Rhodesian Railway and its successful accomplishment is a remarkable testimony to the efficiency of modern engineering methods.