Using recycled plastics to make railway ties reduces the carbon footprint of construction—especially when you consider what otherwise becomes of it. "Recycled ABS is significantly more suitable for use in track structures due to its superior mechanical durability," write the authors. "Additionally, recycling ABS as a sleeper material significantly reduces overall GHG emissions compared to incineration."
This research explored the potential of using two types of recycled plastics, which are currently incinerated, as materials for railway sleepers. From these waste plastics, ABS and LPB repulping reject, ABS emerges as a significantly more promising alternative for sleeper material. Recycled ABS material is approximately three times stronger and stiffer than LPB repulping reject. Based on mechanical testing, the strength properties of recycled plastics are relatively similar to those of virgin ABS and LDPE. Sleepers made from recycled ABS are moderately suitable for all types of tracks, with a particular advantage for freight traffic lines. On the other hand, sleepers made from recycled LPB repulping reject are prone to excessive softening in summer temperatures and cannot be used as railway sleeper material in their current form. While it is possible to increase the softening point with additives, this was outside the scope of this research.
Steel sleepers have the largest carbon footprint, followed by concrete. Though hardwood is much lower, it's still significantly higher than recycled plastics. According to the paper, published in Frontiers in Sustainability, this aspect of construction accounts for 30% of total emissions. If I remember rightly, "recycle plastics for structural purposes" is one of the crazier things the GDR did—and now it turns out they were right all along! Choo Choo! Now lets find out what the microplastics footprint of a slowly deteriorating, regularly vibrated ABS log is.
Previously:
• Railway workers built secret apartments in train stations
• Japanese railway melodies played on pocket calculators
• How railway travel inspired American diner architecture
