1. What de-icing agents do you use on large sensitive structures, such as tunnels and bridges?
Our main gritting operations use spreading salt (sodium chloride) across our network, including in tunnels and across bridges, which is pre-wetted using a 22% salt brine solution. Further information can be found on the Devon County Council website in the Winter Service and Emergency Plan.
In Exeter, we are trialling the treatment of some of our cycleways and footways, which does include a number of bridge structures. Here we are using a direct liquid application which is a brine solution blended with a corrosion inhibitor.
2. What are your current spread rates for the de-icers?
Spread rate is informed by several factors including forecast road surface temperatures, precipitation, time of treatment. This is set out in in Section 8 of the Winter Service and Emergency Plan.
3. Do you follow the manufacturer’s guidance when using the de-icers?
Yes, spreading vehicles and plant are operated as per manufacturers guidance.
4. Have you noticed significant issues with corrosion on these assets when using your specified de-icers?
No. Whilst it is acknowledged that the County Council has structures that have corrosion, none has been solely attributed to de-icers. Where new de-icing strategies are developed, the application on structures is considered and de-icers with corrosion inhibitors are chosen along with a suitable method of application.
5. Have you ever used other de-icing agents in the past?
Yes
5a. If so, which ones?
Historically, we used dry salt without the pre-wet application . Pre-wetted application was introduced over 15 years ago.
5b. What were the reasons for discontinuing their use?
Pre-wet was proven to be more efficient than using ‘dry’ salt, sticking to the roads and activating straight away rather than requiring moisture/car tyre interaction.
6. Have you ever trialled any other de-icers?
Collaboration has taken place in the past with our Materials Laboratory and other research groups but the conclusion reached by the County Council is that pre-wet application salt offers the most cost effective de-icing solution.