Precautionary and reactive treatment
During the winter period, which runs from 1 October through to 15 May, the OCs must allow the safe movement of road users and minimise delays and disruptions caused by snow and ice. To do this, the OCs carry out precautionary and reactive treatments.
Precautionary treatment is when de-icing material is spread on road surfaces when low temperatures are forecast. Reactive treatment happens when ice has already formed on roads or footpaths and is often done in conjunction with snow ploughing.
The OCs decide which treatments are necessary to comply with the contract. They are also required to collect information on, and keep records of, the work they do to maintain the network in winter.
Winter patrols are also carried out on certain risk assessed routes and de-icing material is spread where necessary.
2.4 Winter
Winter Service
Transport Scotland’s aim is to provide a 24-hours a day, 7-days a week dedicated and efficient service during the winter period, which runs from 1 October to 15 May. The main objective of winter service is, as far as is reasonably practicable, to keep the network free of ice and snow, thus reducing the risk to road users.
Winter weather conditions
Figure 28 shows winter weather conditions on the network. Met Office figures indicated winter 2007/08 was marginally colder than the previous year.
Road closures
The OCs responded well to snow conditions and high winds experienced at the end of December 2007 and beginning of January 2008. These caused significant traffic congestion following the closures of the Erskine, Tay and Forth bridges.
There were more road closures due to winter conditions than in 2006/07.
Figure 29 compares the 2007/08 winter with previous winters.
| Winter Period | No. of winter related major incident road closures |
| 2007/08 | 6 |
| 2006/07 | 3 |
| 2005/06 | 7 |
| 2004/05 | 4 |
| 2003/04 | 11 |
| 2002/03 | 4 |
De-icing material
The major change from the 2G to 3G contracts is the requirement for pre-wetted carriageway treatment, instead of dry salt treatment. This system involves pre-wetting the salt before it is spread on the road surface.
Figure 30 shows pre-wetted de-icing material comprises 70% fine grade salt and 30% brine. Pre-wetting uses salt more effectively and efficiently. In snow conditions, dry salt is used in conjunction with ploughing.
Figure 31 shows pre-wetted salt being spread on the network. Figure 32 shows a snow plough on the network as part of the winter service operations.
