The points raised in Raymond Cowen's letter (NCE 2 November) about temperature induced tensile and circumferential tensile strain in train rails were extremely relevant.
Add to this the centrifugal effects, both horizontally and vertically, during the passage of trains round bends and the required contribution of the outer rail, compared to the inner rail, is awesome.
Railtrack has now found 500km of track in need of replacement and it would be interesting to know whether this will be shown to be due to defects on the outer rail at curves in the track. Having carried out a relatively simple analysis of these findings, it would be simple to install inexpensive monitoring equipment to assess the separate effects of curve diameter, temperature and train induced forces. I suspect the latter would be found to be the most significant.
If this were so, it may be that the addition of cables between the sleepers and newly provided anchorages on the inside of the curve would be a relatively inexpensive and effective solution in limiting the worst of these stresses. Such a system could easily be designed to provided restraint on all the track by tying sleepers on one track to sleepers on the other.
Calvin Barrows Calvin_Barrows@bigfoot.com