Book review: Service Life of Surface Treatments

This document was published in May 2011 by the Association of Directors of Environment, Economy, Planning and Transport (www.adeptnet.org.uk) (the organisation previously known as the County Surveyors Society) and the Road Surface Treatment Association (www.rsta-uk.org), the trade association for the surface dressing, slurry/microsurfacing, high-friction and allied treatments industries. It is available for download free of charge at http://www.rsta-uk.org/downloads/RSTA-ADEPT-Service-Life-document.pdf.

All highway authorities are required to produce life cycle plans for their assets in order to calculate the annual depreciation of those assets. These will be formally audited starting in financial year 2012–2013. This process will require authorities to attribute remaining useful life spans to individual sections of carriageway. What the Service Life of Surface Treatments seeks to do is to set out what are the expected service life periods of three surface treatments

• surface dressing

• microsurfacing (including slurry)

• high-friction surfacing.

Service life is defined as the ‘average’ or ‘typical’ life of a treatment while the life of a treatment is defined as ‘the time at which significant maintenance becomes necessary’. Each of the surface treatments is considered against the headings

• description/definition

• service life

• guidance to follow to achieve life

• key compromising factors

• failure modes

• notes.

The key part of the document is the Recommendation section, which contains a table relating service life to the type of surface treatment. The service life values are given for the four surface treatments listed above (microsurfacing and slurry surfacing are rightly accorded separate sections in the table). This table is reproduced as Table 1. There is no doubt that the aim of this document is very laudable. Despite the fact that the contents of the table are unsurprising, it is useful to have them recorded in one publication. However, the table would have been enhanced if it had made reference to the traffic categories that feature in Road Note 39 and which are mentioned elsewhere in the document. Unfortunately, the report itself contains a number of avoidable flaws. These include poor syntax, the tables give numerical percentages for ‘Effect’ and these are of doubtful value, in places it reads like an advertisement for the RSTA and the references are listed inconsistently.