Putting winter to the test


The NWSRG is on a mission to expand its influence across the sector. Its research could have an international impact and some of its most interesting work is happening in Scotland, most notably the well-publicised brine versus pre-wetted salt trials, which are due to start again this winter.

Mr Thomson gives Highways an update: ‘Phase 4 trials are due across 2017/18 winter. The criteria for the Phase 2 and 3 trials was to use brine for precautionary treatments on damp or wet roads to -5°C. The results of these two phases demonstrated that brine provided an effective service in these conditions and brine spreading was a suitable treatment on the majority of days when spreading occurred on the trial sites.


‘Based on the conditions under which brine spreading has been trialled to date, recommended spread rates have been provided for precautionary treatments before frost and light snow or rain.

‘It has been considered there is scope for the use of brine for a wider range of conditions, for example before and during more significant snow events, if the effectiveness can be demonstrated operationally on the network.

‘Further trials are proposed over the 2017/18 winter season to include brine spreading to be carried out before and during snow events and in temperatures below -5°C.

‘The overall aim of the trial is to assess the suitability of full liquid treatments for delivering our next generation of contracts with procurement commencing next year, building on the experience of the previous winter trials.’

Mr Thomson says the key objectives are to:

  • Assess the effectiveness of brine treatments applied before and during snowfall
  • Assess the effectiveness of brine treatments for road surface temperatures below -5°C
  • Identify the limits of effectiveness for brine spreading in comparison to current pre-wetted and dry salt treatments
  • Where limits are identified, assess other options that can be applied, eg higher brine ratio for pre-wetted salt or addition of optimum blends

He adds: ‘Phase 4 trials will commence in November to monitor the effectiveness of brine for snow treatments and extreme cold temperatures on the A835, which recorded the lowest road surface temperature on the trunk roads during the 2016/17 winter season.’

Transport Scotland has leased a combi-flex spreader that is currently being custom manufactured for the trials. The spreader is a combination of dry salt and liquid in the ratio of 30:70, Mr Thomson reveals.

Transport Scotland and the Society of Chief Officers of Transportation in Scotland (SCOTS) have representatives on the NWSRG steering group and Peacock Salt and Findlay Irvine are on the Technical Advisory Group (TAG). However Mr Thomson candidly describes how the NWSRG’s overall presence north of the border has room for improvement.

The Scottish road network comprises 3,400 km of trunk roads and 56,000 km of local roads. Transport Scotland is responsible for overseeing the management and maintenance of Scotland’s motorways and trunk roads.

The 32 local authorities have the responsibility for managing local roads. Collaboration, particularly at the local level, is a big issue in Scotland.

Mr Thomson tells Highways that Transport Scotland continues ‘to collaborate and support winter service best practice on a local, national and world level through our current relationships with local authorities, Highways England, the NWSRG and the World Road Association (WRA)’. Transport Scotland also attended the annual pre-winter meeting of the SCOTS Winter Service Sub-Group last month, which has appointed a new chair – Keith Milne of Aberdeenshire Council.

As a member of the WRA Winter Technical Committee, Mr Thomson on behalf of Transport Scotland helps share best practice in Scotland, the UK and internationally.

‘Transport Scotland is actively supporting the WRA with its involvement in its winter technical committee. This shall include presenting a paper at the next Winter Road Congress (February 2018) in Gdansk, Poland.

‘Highways England has also recently invited Transport Scotland to be part of a European Winter Service Interest Group, which meets on an annual basis and includes specialists from Belgium and the Netherlands.’

On top of this, Transport Scotland recently chaired the annual five nations (Scotland, England, Wales, Northern Ireland and Republic of Ireland) winter teleconference on 21 September.

Cold Comfort 2018, the 27th Annual Winter Maintenance Conference and Exhibition takes place at the Ricoh Arena, Coventry on 16 and 17 May 2018.

Register your interest today at https://coldcomfort.tn-events.co.uk and we will keep you informed with the Early Bird Discount offers and programme updates.

This article first appeared in the November issue of Highways magazine. 

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