Whilst we provide a generally good winter service it is important to realize that there could be more cost effective approaches to winter maintenance than just spreading dry salt. In many instances this traditional approach will be sufficient.
However a ‘one size fits all’ approach rarely reaps the best results, and in some cases it may be more beneficial to think outside the box to improve the UK’s resilience to severe winter weather.
Councils and contractors are striving to provide not just the best possible service, but one that is also kind to the environment, keeps road users safe and ultimately saves money. So what alternatives are currently being investigated?
Pre-wetting is now well documented and has steadily grown in popularity since the late 1990s when it was first introduced into the UK. Having been adopted on the continent for some time the pre-wet approach, whereby salt adheres to the ground and enters into the solution more quickly, enables the thawing action to begin sooner. This method has been shown to reduce salt usage preventing the wastage of material and increase residual salt levels than that of dry salting.
It is also particularly helpful in geographical areas or coastal locations that are flatter and less trafficked where greater control and faster action is needed. Operators of this method believe a 20% salt saving can be easily achieved.
Of course this de-icing approach will not be right for all. Also, many local authorities with restrictive budgets may struggle to raise the capital needed to convert their fleet to pre-wet for instance, even if they acknowledge the technique’s effectiveness and savings that could be incurred in the long-term.
A more preventative approach to keeping roads clear and providing greater long term cost efficiencies would be the consideration of a full liquid methodology. A technique that has been common in Europe since the 1980s, this sees roads being sprayed with pure brine before the snow and ice hits.
Utilising even less salt than the aforementioned technique, this treatment does not require any activation from traffic to become effective and greatly reduces the amount of salt required to treat the network.
There has been extensive independent research into liquid spreading and some interesting facts come out of this research, which might come as a surprise. The application of liquid de-icers or Anti–Icing instantly forms a bond breaker between the road surface. This reduces the chance that ice will form and bond to the surface. The similarity has been drawn to how cooking oil prevents food from sticking to the frying pan.
Some independent research has shown that approximately 85-90% of the NaCl from the brine lands on the carriageway after spreading and binds so hard to the surface that the traffic must wear it off, while only 60-65% of the NaCl from pre-wetted salt lands and binds to the surface. Further to this the research showed that at low traffic counts the relative loss of salt at 2 hours is “21%” higher for pre wet than by brine spreading. At high traffic counts the difference is “30%”.
If the figures are interpreted directly it means that at high traffic counts the amount of NaCl spread as brine can be reduced by 36% and still the residual amount of salt after 2 hours is at the same level as for pre-wetted salt. Some of this is evidenced in research over a 12-year period where a 14% reduction in snow and ice related incidents were claimed.
My own conclusion from the research I have seen is that by spreading brine you can significantly reduce material costs, greatly increase residual salt levels on the network, and deliver the material with greater efficiency.
Brine spreaders allow longer route lengths to be designed with fewer machines required as they can also deliver the material for precautionary salting at greater speeds whilst reducing the risk of claims and damage to vehicles owned by members of the public.
I believe technology is perhaps as important a consideration as the type of material used, this type of spreading equipment can be specified with the same state of the art control systems used on conventional spreaders but are generally more cost effective to buy and maintain throughout their lifetime because they are mechanically simplified machines with less moving parts to cause potential problems.
This equipment is also not a one trick pony sat around for 6 months of the year idle and could also be used all year round for work like application of dust suppressants to reduce pollution in city areas or for street washing and cleansing of spills.
One final interesting fact taken from research is that it apparently takes three times the amount of resource to remove compacted snow when ineffective precautionary salting has taken place which makes you think that effective anti- icing with greater residual salt levels will greatly reduce overall time and costs when snow clearance events do occur and resources are stretched.
There is the argument that shorter, sharper cold snaps are perhaps more common in the UK than extended periods of snowfall and with 80-90% of our salting runs being precautionary operating a highly efficient anti-icing operation I believe should in the long-term make economic and environmental sense. Once again innovations effective on other continents have the ability to reap real advantages for the UK.
John Saint is Epoke Product Manager at Scarab
