Around the world, wood is the most important and most frequently used renewable resource.
The woods used in Europe for the production of wooden sleepers originate entirely from sustainably managed forests – which is frequently documented by an FSC or PEFC certification.
In the environmental categories primary fossil energy needs and global warming potential of its non-wood competitor products, wood has numerous ecological advantages compared to other materials. This is because of the fact that during the biological production of the wood – i.e. the growth of the tree – regenerative primary energy is stored in the wood and later in the product which is made out of it, until the primary energy can be recovered finally, at the end of the product’s life. Likewise, during the growth of the tree, large quantities of carbon or carbon dioxide are stored in the wood and are bound there for the entire time of the product’s use. They are only released again at the end of its life.
The current life cycle assessment study (Life cycle assessment of railway sleepers – Comparison of railway sleepers made from concrete, steel, beech wood and oak wood) by EMPA from the year 2021 shows, that the eco-profile of wooden railway sleepers has improved significantly compared to an earlier study from 2009. This is due to the conversion to creosote type C in accordance within EN 13991 and the use of new, alternative wood preservatives in connection with their application according to German standard DIN 68811:2007-01.
The study also determines that the eco-profiles of the beech and oak sleepers hardly differ from one another at all.
Energy recovery for the sleepers typical today due to the Waste Wood Ordinance proves itself to be essential for a profitable eco-profile of the wooden sleepers.
Over their service life wooden sleepers store roughly the same amount of CO2 as carbon, as greenhouse gases are released from fossil sources throughout their life cycle, including track construction, maintenance and servicing. Around 126 kg CO2 is stored in each wooden track sleeper (beech and oak). Extrapolated to the entire DB railway system with 11,1 million units, that is nearly 1,4 million tons CO2 which is stored in the wooden sleepers today (see SGH position paper “The wood sleeper as a CO2 store and its contribution to climate protection”). According to industry estimates 25,0 million tons of CO2 are stored in wood railway sleepers all over Europe.
If waste sleepers are used properly thermally – preferably in combined heat and power generation – through the substitution of fossil energy sources roughly just as much CO2 will be avoided as is emitted over the life cycle of the wooden sleepers, including track construction and maintenance. So, in sustainable forest management, wooden sleepers are not only CO2 neutral with respect to their biogenic carbon dioxide, but are also “first choice” with respect to the CO2 from fossil sources.
Thus the use of wooden sleepers is also a valuable contribution to climate protection!
