Freeze and Thaw Cycle: Tackling road defects in the North West of Scotland12 Feb 2018

BEAR Scotland is doing all it can to carry out repairs across trunk roads in the North West of Scotland after harsh weather conditions experienced earlier this year had a detrimental effect on sections of the network.

Now an ongoing £24M programme of surfacing improvements at over 200 locations across the North West is well underway. 

BEAR Scotland’s North West Planned Maintenance Manager explains the science behind the cause of this deterioration across the road surface and how BEAR teams are carrying out repairs.

A road pavement has a natural life cycle and at some point it will require maintenance, repair and replacement. While most of these repair and replacement projects can be planned, a road surface can fail prematurely. Such failure can happen over the course of months, or it can be very sudden.

Asphalt (“flexible”) road surfaces, such as those that make up most of the trunk roads BEAR manage, are known for their durability and resilience. Its strengths make it a highly used material for many road surfacing applications and is by far the preferred material for the vast majority of roads across the UK, and indeed Europe. Like all paved surfaces however, it is susceptible to deterioration due to the actions of nature. Despite the great longevity of a properly laid asphalt surface, even under heavy traffic, its life can be rapidly cut short simply by exposure to exceptional weather conditions. 

Freeze and Thaw Cycle

Over time, a road pavement will naturally deteriorate as the materials that make up the road become affected by temperature, rain (especially freezing following after heavy rain), sunlight and chemicals (such as diesel) that come into contact with the surface. 

The asphalt binder that is the “glue” of the road slowly begins to lose its flexibility under traffic and the actions above, tiny cracks form, reducing its natural resistance to water, allowing the water to penetrate into and underneath the road pavement. Once this happens, the surface can quickly fall prey to a number of different types of deterioration. 

Due to the expansion and contraction of water when it freezes and thaws, in freezing water expands in the voids within the carriageway’s matrix which can lead to tearing of the binder which holds the aggregate in the road together. This generally happens at surface level where the frost penetrates the upper layers. With the repeated expansion and contraction the stones in the road surface begin to loosen as their bond with the binder (the “glue”) is weakened. The more often this happens, the greater the rate of deterioration. This is a major contributory factor to formation of potholes.

In a section of road where surfacing materials are all of the same age and composition, locally accelerated deterioration can occur on a rapidly spreading basis as water penetrates not only from the running surface downwards, but also through the areas of looser stone which occur on the sides of a pothole as it forms and grows in size under the combined action of traffic and the elements.

This freeze/thaw action happened across the North West network at an extraordinary rate over the winter 17-18 period due to the range and frequency of temperature fluctuations above and below the freezing point. Between December 17 and March 18 alone this freeze/thaw cycle occurred on 58 days - the highest number recorded in the last five years.

On the A85 in Connel, one of the many areas very badly damaged by the weather earlier this year, road surface temperatures in December 17 ranged from a high of 10.3C to a low of minus 6.5C degrees which, when coupled with heavy rain in the same month, meant that the road surface had begun to break down in some places due to this flux in temperature and weather conditions.

Challenges

Fixing potholes in winter is difficult as snow, ice, water and moisture naturally collect in the holes and cracks. The existing pavement needs to be dry for most hot asphalt mixtures to form a solid, permanent bond. If any moisture remains in or near the pothole during the repair it can start the deterioration process all over again: freezing, expanding and allowing room for more precipitation to enter and expand further. When air temperatures have dropped to below minus 12Co as they did in January this year, it is a real challenge to repair road surfaces in winter conditions.

As a result, and due to the accelerated rate of pothole development in the last few months, the fallback solution used to overcome this has been to place a special temporary repair material into potholes to minimize the risk of them enlarging until a permanent repair or general resurfacing can be delivered when warmer and drier conditions prevail.

That’s the reason the spring and summer months are ideal for conducting road repairs wherever and whenever possible.  However, at the same time we have to consider the condition of the deteriorated road surface, the resources available to us and the impact our work has on road users and therefore we strive to plan our works to minimise disruption to local communities and the important tourist economy.  

What are BEAR doing to carry out road repairs?

BEAR are urging people to report potholes. This can usually be done through the BEAR website under the ‘report a defect’ function, or by calling Transport Scotland’s Freephone trunk road customer care line on 0800 028 1414.

Our teams are now well underway with a £24M programme of surfacing improvements at over 200 locations across the North West Unit before the end of this year, with teams working to minimise any disruption to road users wherever they can.  

For all up to date traffic information, visit Traffic Scotland at www.trafficscotland.org, their new mobile site at my.trafficscotland.org or on twitter @trafficscotland.

Back to news list

£650,000 urgent resurfacing repair programme launched for A8306 Feb 2018

Works commence from Tuesday 6th February

Click here to read about progress through the A83 urgent repair programme

Motorists using the A83 between the Rest & Be Thankful and Whitehouse are to benefit from an accelerated repair programme, as £650,000 worth of urgent resurfacing works are carried out starting in February 2018. 

BEAR Scotland, acting on behalf of Transport Scotland, are planning to carry out urgent resurfacing works on a sections of the A83, situated between Rest & Be Thankful and Whitehouse.  The route is being inspected daily and hundreds of temporary repairs have been made in the past two months.. This inspection and repair work remains a priority and will continue however it requires to be followed up by permanent repairs. 

Click the link at the bottom of this page to download a copy of the A83 programme of urgent repairs.

Following successful discussions with our surfacing contractor, we are pleased to announce that the programme for repairs will now commence on Tuesday 6th February. A rolling programme of work will be carried out in order to address the most urgent locations on the route. Work will be carried out between 7am and 7pm each working day.

The majority of work will be carried out under convoy working, however, due to restricted road widths at certain locations some work will require periods of ‘STOP/STOP’ working. Motorists should therefore expect some delays.

Emergency services will be able to pass through the works at all times. Access to properties within the closure and for local bus services will also be maintained at all times, although some delay is inevitable. The road will be fully open during the day.

Eddie Ross, Operating Company Representative for the North West Unit, said:“A spokesperson for BEAR Scotland said: “We’re pleased to announce we have successfully accelerated a programme of work to address sections of the A83 which have deteriorated rapidly following the harsh freeze and thaw cycle experienced earlier this month.

“£650,000 has been set aside to address defects specifically on the A83, with teams working to prioritise multiple areas across the route between the Rest and Be Thankful and Whitehouse.

“Some of these areas were identified for future surfacing last year and added to our upcoming programme of planned work, however sections have deteriorated badly following the huge impact of ice and freezing winter weather causing the road surface to break up and have been brought forward.  Others are new additions to the programme that were also impacted by the winter weather.   

“In the meantime teams are carrying out temporary repairs where possible, erecting signs to advise motorists of the uneven road surface in some places and carrying out weekly safety inspections across the whole network to note any defects.

 “Should anyone wish to report a specific defect on trunk roads, please call the Freephone number 0800 028 1414.”

 Real-time journey planning information can be obtained by visiting www.trafficscotland.org or twitter @trafficscotland.

New File

Back to news list

Safety message to motorists using A9 Cromarty Bridge30 Jan 2018

• Motorists to adhere to the 30mph speed limit and traffic signals

• Joint safety message from BEAR Scotland and Police Scotland

The £1.5M bridge improvement project on the A9 at Cromarty Bridge has returned to site following the Christmas break.

The project began in August 2017 to carry out concrete repairs to the bridge deck and supports as well as the installation of protection measures to prevent future deterioration.  The bridge deck will also be waterproofed and resurfaced to ensure a smooth and safe journey for bridge users.  

For the safety of the workforce and travelling public, traffic management has been installed on the bridge since construction began and it is continually monitored and reviewed. There have been regular instances of road users “jumping” red lights and speeding through the worksite. Both of these unsafe acts endanger teams working on the bridge and other road users. BEAR are committed to site safety and creating safe places of work for its staff and sub-contractors as a priority. This cannot be achieved without assistance from motorists crossing the bridge.

The traffic management is in place to protect workers from being struck by vehicles or debris on the carriageway. Motorists are reminded to not exceed 30mph within the worksite and to obey the traffic signals.

Police Scotland Road Policing Inspector, Neil Lumsden, said: “These traffic management measures are in place to ensure the safety of workers, the travelling public and improve journey time reliability. A small minority of motorists have chosen to ignore temporary speed restrictions and red traffic lights and I would like to remind the public that we will continue to work closely with BEAR Scotland to ensure the site is safe for all road users. Regular marked and unmarked patrols and checks will be carried out to deter this type of behaviour and motorists caught breaking the law will be robustly dealt with.”

Eddie Ross, BEAR Scotland’s North West Representative said: “BEAR and Police Scotland are committed to safety and we rely on cooperation of motorists to ensure our site teams are safe. I stress the importance of keeping to speed limits and obeying traffic signals as this allows teams to work in a safe environment.”

Real-time journey information is available from Traffic Scotland on www.trafficscotland,org , twitter @trafficscotland or on the new mobile site my.trafficscotland.org. 

Back to news list

£5.4M Resurfacing Programme Completed on A914 Dec 2017

BALLINLUIG TO THURSO

- Sustainable methods used will help prolong the lifespan of the road 

A £5.4M programme of road surface improvements has been completed on the A9 between Ballinluig and Thurso.

The investment by Transport Scotland, saw sixteen sections of the A9, totalling 14.6km, resurfaced between February and November 2017. The works deliberately avoided busy summer periods and have benefitted the thousands of motorists using the route each day.

The programme saw approximately 34,500 tonnes of new asphalt laid, fixing defects and improving the overall quality and safety of the road surface for drivers. 

An innovative sustainable method was used in ten of the sixteen schemes. The ‘Crack & Seat’ process extends the life of the existing road by introducing a series of hairline cracks in the cement lower layers which then distribute the strain more evenly. By reusing these existing cement bound lower layers it gives a more stable base and increases the lifespan of the carriageway. Using this sustainable method in these schemes saved approximately 27,000 tonnes of material compared with traditional reconstruction.

Furthermore, as part of the overall resurfacing programme, over 80,000m2 of TS2010 surface course was laid. This bespoke surface course, developed by Transport Scotland, will provide an enhanced lifespan when compared to traditional alternatives and will reduce the need for future maintenance.

Eddie Ross, Operating Company Representative in the North West for BEAR Scotland said: 

“The A9 is a major strategic trunk route that is used by thousands of road users on a daily basis. This significant investment by Transport Scotland supplements the programme of dualling the route and allows this key artery in Scotland’s road infrastructure to continue to operate safely and effectively for years to come, providing vital access for people to and from the North.

“By using more sustainable methods and materials we have prolonged the life expectancy of the road and minimised future need for maintenance.” 

All works were undertaken by Breedon Aggregates on behalf of BEAR Scotland. 

Back to news list

BEAR Scotland preparing for Storm Caroline06 Dec 2017

Amber weather warning issued for high winds on Thursday

Yellow weather warnings in place for snow and ice from Friday to Saturday evening

BEAR Scotland’s resources are prepared to assist in dealing with the “Storm Caroline” conditions with winds of up to 90mph forecast at exposed locations mainly across the north of Scotland.  

An amber ‘be prepared’ weather warning has been issued for high winds across the Grampian and Highlands and Eilean Siar areas by the Met Office valid from 6am on Thursday morning until midnight.   

In addition to Thursday’s amber wind warning, a yellow warning will follow from midnight for snow and ice until 6pm on Saturday.

Resources across the North West and North East units are on standby including over 100 operatives equipped to deal with issues on the trunk roads brought by the high winds, with four gully tankers as well as sandbags and water pumps available to deal with any flooding issues.  Teams will work around the clock to maintain the routes and conditions across the network will be monitored 24/7 by BEAR’s control room. 

As Storm Caroline will bring colder temperatures, BEAR’s winter teams will be responding by carrying out precautionary salt treatments across all trunk roads in the north east and north west of Scotland, followed by all routes being patrolled to clear any snow.  BEAR’s winter fleet includes 115 vehicles across 22 depots, and teams will be on high alert to respond to any wintry conditions affecting the network.  

BEAR Scotland is working closely with Police Scotland and Transport Scotland to respond to tomorrow’s high winds across the North West and North East, followed by the ice and snow that is forecast to continue until Saturday.  

Eddie Ross, BEAR Scotland’s Representative for the North West, said: “At present we are preparing for the forthcoming high winds and our teams are on standby to assist in whatever way possible to keep road users safe and moving.

“In addition to our normal emergency response specialist landscaping teams will be positioned across the north of Scotland tomorrow to deal with any trees or branches that may fall on to trunk roads.

“We’re also gearing up for the forthcoming drop in temperatures and forecast snow, with our fleet of gritters and other winter vehicles ready to tackle any adverse weather conditions.

“We would advise motorists to be alert and prepare in advance for the adverse weather by checking travel information via the Traffic Scotland website, twitter or mobile site as well as local radio before setting off, allowing extra time for journeys and making sure to drive to conditions.”

Transport Scotland’s online ‘trunk road gritter tracker’, launched last winter, provides live tracking of gritters on the trunk road network.  The tracker can be accessed through the Traffic Scotland website at www.trafficscotland.org/wintergritterinfo/.  

Real time journey information is available from Traffic Scotland on www.trafficscotland.org or twitter @trafficscotland or the new mobile site my.trafficscotland.org.

Back to news list

BEAR Scotland primed and ready to deal with winter conditions 21 Nov 2017

• 57,000 tonnes of salt ready to treat trunk routes across north of Scotland

• 180 strong winter team ready to tackle winter conditions

• Winter control room to monitor conditions 24/7

BEAR Scotland’s winter maintenance services are up and running and ready to tackle whatever winter weather affects over 2000km of trunk roads across the North East and North West of Scotland.

BEAR Scotland’s winter maintenance team works around the clock, analysing detailed weather forecasts to ensure treatments are carried out as necessary. It has 57,000 tonnes of salt in stock, a workforce of 180 drivers and a fleet of 94 winter vehicles dedicated to helping keep the trunk roads as clear as possible. 

Much of the service is related to precautionary treatments – spreading pre-wetted salt on routes that will experience low temperatures – in a bid to stop ice forming. The service also is made up of winter patrols which monitor routes with an ability to spot-treat any icy patches.

Transport Scotland’s online ‘trunk road gritter tracker’, launched last winter, provides live tracking of gritters on the trunk road network.  It displays the current location of gritters and a trail with an age range for where gritters have previously passed along trunk routes across Scotland.

BEAR is also on hand to deal with any issues on the trunk roads brought by storms that bring high winds and heavy rain. Gully tankers, sandbags, and water pumps are available to deal with any flooding issues and chainsaw operatives are also on standby to attend any fallen trees or branches.

Iain Murray, BEAR Scotland’s Managing Director, said: “We have 180 dedicated, trained and experienced employees ready to deal with winter across the trunk roads that we maintain. Our winter control room monitors road conditions on a 24/7 basis meaning we can act quickly to changing winter weather conditions from the challenges of low temperatures and snow to bad storms.

“As ever, we ask members of the public to ensure their vehicles are well maintained, that they pay close attention to local and national media and online information to help plan journeys during inclement weather and that they carry equipment to help themselves should conditions deteriorate.”

Back to news list