This report is Part 1 of a two-part study of the long-term performance of reinstated trenches and their adjacent pavements. It contains a review of national and international research carried out on reinstatements in footways and carriageways over the last decade, including UK research since the introduction of the NRSWA Specification (HMSO, 1992). The main aim of the review is to assess whether the rate of deterioration of the reinstatements is higher than the adjacent pavement and whether the presence of the existing reinstatements has had an effect on the life of the adjacent pavement. The report presents evidence as to whether non-compliance with the Specification and variation in the quality of workmanship, materials and methods have had any significant effects on the service lives of pavements. In some cases, authors have made general qualitative deductions to evaluate the likelihood of long-term damage that may result from reinstatements in the highway. To increase knowledge on long-term performance of reinstated trenches and their adjacent pavements, further evidence of existing reinstatement and adjacent pavement performance would need to be gathered and analysed. With the implementation of the 2002 edition of the Specification, practices should continue to improve but the presence of reinstatements may in itself result in the need for premature maintenance intervention. Finally, whilst some evidence concerning surface deterioration is given in the reviewed reports and papers they provide little research evidence about the environmental disbenefits of trenched carriageways, footways and cycle tracks. Further investigation of this aspect is needed. (A)

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