Scottish councils still overwhelmingly use paint for road markings that damages the environment, The Ferret can reveal.
We asked all 32 Scottish councils what kind of paint they use and 24 said it was exclusively, or predominantly, a toxic thermoplastic paint. Eight councils did not comment.
Cold plastic paint is safer, cheaper and more sustainable, according to the European Commission. But many councils still use thermoplastic paint with a global warming potential that could be 136 per cent greater than the alternative. Thermoplastic paint has been ditched by countries such as Austria or Switzerland but is still used in 95 per cent of UK roads.
The environmental impact of thermoplastic comes not just from its lesser durability but also because it needs to be applied in a molten state, meaning a mobile apparatus – usually a lorry with an open air flame – is needed to keep the material at around 200C.
Cold plastic is more durable and does not have to be replaced so often. This reduces the frequency of work zones on the roads and contributes to accident reduction by providing more visibility and keeping roads clear of works for longer periods.
A report commissioned by Transport Scotland, published in 2015, acknowledged problems with the “durability of thermoplastic road markings”. The report showed a Glasgow contractor suggested cold plastic paint as an alternative.
In 2018 the European Commission (EC) published a report after analysing a study by the Austrian Institute for Industrial Ecology. The EC concluded that cold plastics road marking systems were the most sustainable solutions for Austrian roads
The report compared thermoplastic and cold plastic. It said that while global warming potential may differ depending on the thickness of the layers, thermoplastic paint’s environmental impact can be from 54 to 136 per cent more than that of cold plastic paint.
Other studies go further and say that cold plastic paints are safer than the alternative by holding more retro-reflectivity capabilities for longer periods of time.
European cities with colder winters than the UK use cold plastic even in high traffic urban areas. Zurich is one example. Heiko Ciceri, a spokesperson for the council said: “The work preparation for the marking companies is much larger and therefore not interesting from an economic point of view. In the morning, the workers first have to boil the paint hot and then apply it on the street in a hot form. The handling is not without danger for the employees to work with this hot mass.”.
Ciceri explained that cold plastics were chosen due to better handling, sustainability, durability and prices.
Dr Alexander Klein, who works for German company Röhm, a global supplier of raw materials for cold plastics, published a peer-reviewed study on the sustainability of road markings. He said: “Cold plastics (…) provide an environmentally friendly road marking solution. Lower environmental impact is achieved thanks to its inherent durability and possibility of prolonging service life through refreshment with a thin layer application.”
Klein added that thermoplastic was less wear resistant, so more needed to be used. This, combined with the energy required to keep the paint in a molten state, meant “more CO2 emission compared to cold plastic,” he said.
Stockholm uses both thermoplastic and cold plastic road markings although there is a reason for this. The City of Stockholm Transport Department, said: “The reason why some use more cold plastic, unlike us who use more thermoplastic, is that we use studded tires in winter. The studded tires punch holes in the cold plastic, which greatly impairs durability. Without studded tires, cold plastic generally lasts significantly longer than thermoplastic.”. The use of studded tyres in urban areas is illegal in the UK.
Scottish and UK regulations make no mention of cold plastics and there are no known plans to roll out cold plastic paint tests.
A Glasgow City Council spokesperson said “We have traditionally used hot thermoplastic for road markings in Glasgow. As I understand, this has been considered effective amid the weather conditions often experienced in the city.”
A spokesperson for the East Lothian Council said its representatives attended a demonstration for cold plastic road markings, but this did not result in a switch to this product as “it was noted that the length of curing time for the product (30 minutes) makes its use impracticable for live traffic roads”.
The UK’s Department for Transport says that UK roads are compliant with European standards. A spokesperson said: “The department does not regulate which materials an authority can choose for its road markings.”
A spokesperson for Transport Scotland said it does not have a specifically defined position on the use of thermoplastic road markings in comparison to other products.
Photo Credit: iStock/CreativeCommons