TRL were commissioned by Transport Scotland to support the development and coordination of a second phase of live brine spreading trials for the 2015/16 winter season. Monitoring of routine brine treatments and comparisons to equivalent pre-wet treatments were carried to assess the effectiveness and longevity of precautionary treatments using sodium chloride brine versus pre-wetted salt for UK climatic conditions and on road surfacing types representative of the wider UK network.

Monitoring of the road conditions after brine spreading, using remote surface state sensors, embedded road sensors and from patrols has indicated that brine spreading has provided an effective treatment for the conditions trialled. Spreading 15ml/m² of brine has been demonstrated to be effective to temperatures between -2 and -3°C, and 30ml/m² effective to temperatures between -4 and -5°C on wet or moist road surfaces. Visual observations of brine spreading indicated that spreading at the rates trialled clearly dampened the road after spreading and enabled a uniform spread over the full carriageway width. When spreading during dry conditions, this was observed to dry and leave a visible salt residue on the surface.

Based on the encouraging results of the trials in winter 2015/16 it is recommended that ongoing trials be carried out spreading brine over the full length of treatment routes. This will enable
assessment over a full winter season and experience to be gained spreading in the more varied conditions that will occur along longer treatment lengths.

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