Raising the bar for treatments

Efforts to increase awareness of specialist highway treatments and the benefits they bring are being stepped up by the Road Surface Treatments Association. New best practice guidance documents have been published and work with industry is under way to promote timely interventions to prolong carriageway life.

Surface dressing is beginning to increase in popularity again, but the treatment is down by around a third compared to 15 years ago.

“We have a national pothole crisis and this is partly due to an under investment in sealing the road network over the last 15 years,” says RSTA chief executive Howard Robinson. “Surface dressing is a great way to stop water from getting into the highway, reinstate texture depth and improve skid resistance. But demand from local authorities for surface dressing has dropped by around a third since 1997. In that time traffic volumes have increased and we have seen some of the worst winters in living memory, which has made the pothole problem worse.”

Despite the reduced demand for surface dressing since the mid 1990s, Dr Robinson remains upbeat about the prospects for specialist highway treatments in the near future. A forthcoming Pothole Review, set to be published by Government this spring, is expected to endorse the use of surface treatments to help prevent the formation of highway defects. The RSTA – with support from the Road Emulsion Association – supplied detailed technical input and case study examples of successful applications to the consultant compiling the report for local authority body ADEPT, which is chairing the Highways Maintenance Efficiency Programme pothole review.

“Potholes are usually filled using conventional asphalt material but poor compaction of asphalt can lead to problems,” he continues. “What can be overlooked is the availability of proprietary patch repair techniques, some with HAPAS certification, that are more cost effective in securing a permanent pothole repair. And sealing the surface properly using treatment systems such as surface dressing and asphalt preservations can prevent potholes from forming.”

Specialist techniques such as slurry surfacing can help to extend the lives of footways

One of the reasons for the reduced demand in surface dressing during recent times is due, Dr Robinson adds, to a gradual loss of specialist technical knowledge within local authority highway departments. “Surface treatments have always been a specialist activity compared to mainstream road surfacing. Many highway authority teams have got smaller over recent years and there are now fewer people with a detailed understanding of surface treatments. The RSTA has recently seen an upsurge in requests from authorities to provide training about specialist treatments and we are happy to provide advice and guidance to those who contact us.”

Written material published by the RSTA last year to outline the most effective ways of specifying a range of specialist treatments is helping to raise awareness of various techniques. These include codes of practice for surface dressing, high friction surfacing, retexturing and slurry surfacing including microsurfacing, which have been endorsed by ADEPT. Further new codes for geosynthetics and steel meshes for inhibiting cracking in bituminous bound layers, velocity patching and in situ road recycling were published in January, with ADEPT’s endorsement. These codes of practice go into much detail and can be read alongside a more general overview of the service life of surface treatments, published last May and available for free on the RSTA website.

“This overview is a really important document as it summarises a range of surface treatments available by describing what they are, the benefits of using them and when to use them,” says Howard. “It links perfectly to the principles of asset management and is timely because local authorities now need to determine the value of their highway assets and report annual depreciation in the forthcoming Whole of Government Accounts – a fiscal stability initiative to produce a set of consolidated financial accounting for the public sector. Based on that information, authorities can work out the most effective maintenance strategies to preserve their road values.”

He adds that the highway network accounts for around half of a typical local authority’s asset value and the UK has seen a sustained period of under investment in roads. But the introduction of Whole of Government Accounting should mean more professionals within central and local government realise the importance of maintaining their carriageways.

“We are beginning to win the argument for greater investment in highways but local authorities do not always have enough money. What we are saying is ‘okay, you have a small pot of money, but we can help you to spend it more wisely’.”

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