Discussion on Papers 5–7

MR A. W. PARSONS and MR J. PERRY, Transport and Road ResearchLaboratory, Crowthorne

In reviewing the geologies in which the greater number ofslope failures occurred (Table 1 of Paper 5) we should like toadd two further materials from later surveys which, inembankments, showed significant rates of failure: these areWeald Clay and Lower Lias (Table 1A).

Further details of surveys of earthwork side slopes in thesematerials can be found in the Technical Note entitled'Incidence of highway slope stability problems in Lower Liasand Weald Clay1 by J. Perry.

MR P. S. GODWIN, West Yorkshire Metropolitan County Council,Ossett

With regard to Paper 6 the proposal for a minimum slope of 1:3is viewed with concern in terms of landtake. Simplecalculations indicate that about 100-300 hectares ofadditional land would have been required for the constructionof the Ml motorway between Sheffield and Leeds. This