CONCRETE RAILWAY SLEEPERS

Chronicle (Levin), 18 September 1946, Page 4

CONCRETE RAILWAY SLEEPERS

^ FIRST LAID AT LEVIN TRIAL TEST COMMENCES Forty-eight "pre-stressed" reinlorced concrete railway sleepers were laid on the track about half a mile south of the Levin station yesterday morning. The sleepers were laid as the beginning of a trial to compare them with the type at present in use, which are of Australian hardwood. They were designed by the chief engineer of the Railways Department, ♦old were constructed in England. Because of the heavy traffic on this part of the line, it was considered to be the most suitable place for the test to be made.. The work commenced yesterday. / morning, when a gang of about twenty men lifted out the old sleepers' "and put in the new. It was not an easy job, as the concrete sleepers weigh 364 lbs. alone, jund with the addition of two 29 lb. east iron bed-plates, the weight is such that two men are required at each end, supp'orting its weight with crowbars, while the sleeper is secured to the rails by means of olips and bolts on the bed-plates. Men on the job said that from the point of view of work, the older type were more preferable. The bed-plates on which the s ails rest are separated from the sleeper by a felt pad, which is intended to lessen the vibration. It is not thought that there will be any more noise in the passenger cars with the new sleepers. The sleepers did their first work when a north-bound rail-car passed over the line at 11 a.m. The full testing will be a long Job, as the life of an ordinary hardwood sleeper is about 25 years on a hearvy-traffic line, and a further 15 to 20 years on sidings or secondary lines. However, a preiiminary report will be made in a iew months. Before the war concrete sleepers were tried, but the test on them was discontinued after a year owing to the cracking of the concrete. It is claimed that the new sleepers, also on trial in Britain, will not crack. They have been subjected to a special process, in which the steel reinforcing is put •mder a high tensile stress, which is then used to induce in the concrete compressive stresses, directly opposite to the stresses produced by the weight and motion of trains. It is contended by advocates of the new sleepers that this makes the steel and concrete homogeneous, and afterwards they react equally and simultaneously to the strains upon them. If the sleepers are to be used extensively in New Zealand, the demand could be met for them by building a factory here, a Railway Department official stated yesterday.