Railways, one of the most climate-friendly transportation modes, emit just 31 grams of CO2 equivalents (CO2e) per passenger kilometer—half that of the most efficient electric vehicles. However, the carbon footprint of railway systems can be further minimized. A groundbreaking Finnish study published in Frontiers in Sustainability explains how using sleepers made from recycled plastics instead of traditional ones could greatly reduce greenhouse gas emissions.
Railway sleepers, typically made from steel, wood, or concrete, contribute significantly to the carbon emissions of railway construction and maintenance. On busy train lines, emissions from these materials account for 30% of total railway emissions. This figure rises sharply on less-trafficked routes.
By replacing conventional materials with recycled plastics, emissions from sleeper production and disposal in the railways industry can be reduced. This also supports waste management and recycling goals.
THE FINNISH STUDY: A STEP TOWARD SUSTAINABLE RAILWAYS
A team of researchers from Tampere University, led by Dr. Heikki Luomala, explored the potential of recycled plastics for railway sleepers. They focused on two primary sources of plastic waste:
- Liquid Packaging Board (LPB): A mix of polyethylene, polypropylene, ethylene vinyl alcohol, and polyethylene terephthalate.
- Acrylonitrile Butadiene Styrene (ABS): Commonly used in electronic and electrical equipment.
The study analyzed the mechanical properties of sleepers made from these plastics to assess their feasibility in real-world railways systems.
KEY FINDINGS: ABS OUTSHINES LPB
Strength and Durability
- Sleepers made from recycled ABS demonstrated superior strength and stiffness, closely matching the properties of wooden sleepers.
- ABS sleepers withstood high temperatures (up to 55°C) without significant softening. This makes them suitable for hot climates. Such suitability is beneficial for railways applications.
Environmental Benefits
- Utilizing recycled ABS could reduce annual carbon emissions in Finland by an estimated 3,610 tons of CO2e. This is equivalent to the heating emissions of 1,200 households. This reduction highlights the environmental impact of railways innovations.
Advantages of Plastic Sleepers
- Lightweight and Cost-Effective: Easier and cheaper to transport and install in railways construction.
- Formability: Greater flexibility in design and customization.
- Durability: Resistant to environmental factors like moisture and pests, reducing maintenance needs.
CHALLENGES AND FUTURE TESTING
While the results are promising, Dr. Luomala emphasizes the need for further large-scale testing. Key areas include:
- UV Resistance: Ensuring long-term durability under sun exposure.
- Lifecycle Analysis: Evaluating environmental impact over the sleeper’s entire lifespan and its implications for railways sustainability.
- Compatibility: Ensuring smooth integration with existing railway systems.
WHY RECYCLED PLASTICS MATTER FOR RAILWAYS
Railways are poised to play a pivotal role in achieving global net-zero targets. Transitioning to recycled materials for components like sleepers supports multiple sustainability goals:
- Waste Reduction: Diverts significant amounts of plastic waste from incineration or landfills, contributing to a greener industry.
- Lower Carbon Footprint: Reduces emissions associated with raw material extraction and production, benefiting the railways sector.
- Circular Economy: Promotes the reuse of materials in high-value railway applications.
IMPLEMENTATION AND INDUSTRY INTEREST
The Finnish Transport Infrastructure Agency has expressed interest in the study, signaling potential real-world application in railway projects. The findings align with Finland’s broader efforts to lead in plastic recycling, including the ALL-IN for Plastics Recycling (PLASTin) initiative.
