Asphalt Surface Dressing Case Studies
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Revamping the road to Silverstone
Transport for Buckinghamshire (TfB) is a public/private sector alliance run by Ringway Jacobs and Buckinghamshire County Council to deliver highways services within Buckinghamshire. With tight budgets and deadlines, the race was on when TfB needed to resurface the approach road to the home of British motorsport – Silverstone. Laura-Jo Stocks, communications officer at TfB, explains
Impressive cars, the Formula 1 elite and international celebrities may all spring to mid when thinking of the Silverstone race circuit, but for the Buckinghamshire highways team, it was the approach roads to the track that were top priority.
Transport for Buckinghamshire (TfB) rose to the challenge when task with designing and building a scheme near the motor racing circuit with tight deadlines set for completion before the British Grand Prix at the start of July.
As part of TfB’s summer resurfacing programme, a four kilometre length of deteriorated carriageway between the village of Dadford and the Silverstone track in north Buckinghamshire was identified as a candidate scheme, requiring reconstruction as well as the addition of new features to enhance road safety. Schemes are selected through a combination of analysis of condition data and local councillor knowledge, which assists and informs the decision making process. Once confirmed and programmed, the countdown began and the challenge commenced – to complete the works prior to the arrival of the entourage for the international Formula 1 British Grand Prix.
In addition to the time challenge, a number of innovative processes were used to reconstruct the road which included in-situ recycling of the existing road material, a first for the country, in combination with conventional new pavement and surface dressing methods. This will ensure a high quality surface for the road, in addition to improving skid resistance, with new lining to enhance road safety.
Working to schedule
With only five weeks to complete the scheme the project team made sure this tight schedule was met, ensuring the different contractors engaged to undertake the work were fully coordinated. To achieve this the road was closed for the majority of the works, allowing multiple crews to out work during day and night, which considerably reduced the construction period.
The TfB team also coordinated the resurfacing work with a range of routine maintenance activities including drainage, landscaping, signing, refreshing road markings and work to safety barriers. This guaranteed the most efficient use of the road closure providing a cost saving as well as giving environmental benefits.
Throughout the delivery Transport for Buckinghamshire and Silverstone Circuits worked closely to keep road users, visitors and customers up to date with the latest news of progress. Following completion to time and budget, all traffic management was removed and the road re-opened for use prior to the prestigious Grand Prix event.
Alex Lacey, head of events for Silverstone Circuits, said:
“Transport for Buckinghamshire set themselves a considerable challenge in April to undertake this work within timescales. They rose to this challenge and, through a close working relationship and regular communications between all parties, the works were completed in good time for the 2015 Formula One British Grand Prix, meaning customers, as well as local road users, will benefit from the much improved road surface.”
Mark Shaw, cabinet member for transport at Buckinghamshire County Council, added:
“We are delighted that this project has been such a success, and thrilled at the improvements that will benefit local residents and road users. Working towards such a high profile target date was undoubtedly a challenge, but one that my team undertook confidently, assured that work would be completed to the highest standard within the deadline without compromising quality.”
The expression “win-win” is being used in Pembrokeshire to describe a long term preventative maintenance contract agreed with a bitumen specialist for the county’s roads. NCE reports.
Pembrokeshire County Council (PCC) is something of a special case. For instance it still maintains a direct labour organisation (DLO), for well thought out, practical reasons. The county employs surface dressing as a strategic means of preventing its roads from falling into premature disrepair. And, just recently, it was willing to accept the proposition that letting a maintenance contract from annual to five years plus one.
That contract relates to supply and applications of binder for surface dressing, which the local authority uses successfully, as part of its annual maintenance strategy.
“Extensive programmes of surface dressing have helped us maintain a very good county roads network with few potholes and generally positive public feedback,” says PCC head of highways and construction Darren Thomas. “But we were getting inconsistencies with the chippings, but also – and more seriously – with the quality and application of binder.”
The highways division knew it had to up its game. Surface dressing can be an excellent way of sealing a road’s surface against ingress of water and subsequent frost heave, restoring surface characteristics such as skid resistance and –combined with selective patching – improving ride quality. It is also far less expensive than resurfacing.
“Carried out appropriately, surface dressing is an excellent form of preventative maintenance. That said, in Pembrokeshire I felt we needed to put more emphasis on product quality to extend the lifecycle of our dressing and ensure better value for money,” Thomas says. Also on his mind was raising the skills and qualifications of the division’s own workforce, to improve their efficiency and safety.
PCC has a DLO of around 40 people, including two engineers and three supervisors. Pembrokeshire is a relatively remote county and there is strong support corporately for keeping certain activities internal. Winter working is one reason for maintaining the DLO, as is out of hours response to events. In summer, the crews move over to surface dressing, which, as well as keeping the county’s roads in good condition, ensures continuity of employment.
“Extensive programmes of surface dressing have helped us maintain a very good country roads network with few potholes” Darren Thomas, PCC”
“The county has nearly 2500km of road, 150km of which are A roads, 200km B, with the remainder C or unclassified,” says PCC highways asset manager Rob Evans. “Our surface dressing programme is cyclical, with us re-dressing every eight to 10 years. Our own DLO people operate the chippers and rollers, but traditionally we have contracted out the supply and application of binder, on an annual basis.”
It is over binder supply and application that PCC found itself with difficulties. The county hates failures, but some year’s back was getting them, along with complaints from the public. “We had some tricky seasons, with contractors coming in who didn’t perform well,” says PCC senior works engineer Christian Reynolds. “The problem was, you don’t see the negative side of deficient application or poor binder until the laying season is over. It can then be problematic to get the contractor to return to sort out the remedials.”
This is when binder supplier Nynas came into the picture, firstly through supplying a binder worked consistently well; then as the contractor charged with both supplying and applying the bitumen. “We’re not really into contracting, but the opportunity was there to do a good job and we took it,” says Nynas special product sales manager Steve Waller.
Nynas leads what is effectively a collaboration with Asphalt Reinforcement Services (ARS), a company initially established to improve the performance of asphalt pavement that specialist experience in spraying bitumen.
The two companies have teamed up before with success, notably in the East Riding of Yorkshire and this has continued in Pembrokeshire, where there are now two gangs with four sprayers in operation. One gang is working north of the A40, where the language of choice is Welsh, one to the south where English is more prevalent.
Whatever the language, the reports back from site about surface dressing operations changed from negative to highly positive. The all important opinion of the DLO crews was that the product was good and so was the application. Complaints from the general public diminished and so too did the incidence of failure.
“I’m not aware of any failures having occurred at all since working with Nynas,” says Evans. “It’s been a real turn around.” Even at difficult locations, say a steeply cambered sharp bend, surface dressing has stayed firmly put and worked well.
Part of the success is due to PCC opting to change from standard K170 binder emulsions to polymer modified emulsions (PME). “We encouraged the county to use our Fleximuls, which is an intermediate grade PME, with some Duramuls – a premium grade product – where the going is particularly onerous,” says Waller.
Not everything was perfect, however. Come the end of last year’s surface dressing season, Nynas had to begin preparing its bid for the following year. Winning was not a certainty. There was no security of tenure and, as such, no incentive for the company to invest in plant or additional staff training and skills development.
“The proof of the pudding is in the eating. The no failure rate is a real blessing, especially to me in my dealings with the public” Christian Reynolds, PCC”
There was no certainty that relationships and trust built up one year would be further developed in the next. Waller says that, although Nynas is always keen to advise and support clients, whatever the durations of the relationship, “with a one year contract, there is no imperative for us to help up-skill our client’s workforce or to work with them to hone our joint practice and achieve higher levels of efficiency”.
These facts were not lost on PCC, and the organisation decided to invite the binder supplier – among others _ to bid for a five years plus one “supply and apply” contract to service the county’s surface dressing needs. Nynas won, and now has continuity of work (all things being equal) until 2020.
“As an authority, we’ve got to demonstrate value for money,” says Thomas. “We’re obviously looking for a continuing high levels of service and product, plus efficiencies and economies which lead to savings.
Very importantly, we’re extremely keen that our workforce is well trained and well qualified, and we hope Nynas will play a part in this.”
Nynas is likely to assist, initially via ARS, which holds BSI ISO9001 quality management systems for the supply and application of surface dressing binders.
“The best binders need the best workforce,” says ARS managing director Howard Cooke. “We’re very strict on health and safety, and I will be making sure that everyone working on surface dressing in Pembrokeshire is well versed in their responsibilities, to themselves and others.”
This year’s surface dressing season – the first under the new contract – started last month, and Reynolds says: “I’m convinced this new six year contract will bring benefits and that relationships will build. And the proof of the pudding is in the eating. The no failure rate is a real blessing, especially to me in my dealings with the public.”