The 1989 Government White Paper 'Roads for Prosperity' (see IRRD 823662) envisaged a substantial programme of widening that included 60 per cent of the motorway network in England. This report presents the findings of a literature study of the geotechnical aspects of motorway widening and gives a critique of the different widening techniques available. The report contains four main sections: methods of widening motorways by steepening the side slopes, new and innovative techniques, an economic appraisal of different widening methods, and routes to increase the usage of new techniques. The study found that the speed and reliability of construction were of major importance: furthermore the movement of materials to and from the construction site can considerably increase traffic delays, complicate site operations, and increase costs. A few techniques have not been used widely in the UK but have potential for use on motorway widening schemes. In some cases there are technical, procedural or commercial obstacles to their use. On motorway widening sites, the benefits of innovation must be substantial to justify the risk of using novel techniques. It is therefore likely that the route to their adoption will be through successful usage on less prominent schemes.

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