Life Cycle Assessment in Road Construction to Pave the Way for Sustainable Infrastructure

A road shouldn’t be designed or constructed on a project basis without considering its Life Cycle Assessment (LCA). This comprehensive methodology is essential for evaluating and minimising the environmental impacts of a road over its entire lifespan, playing a key role in developing sustainable infrastructure.

As the global focus shifts toward sustainable infrastructure and climate resilience, LCA has become an indispensable tool for pavement engineers. It enables them to design roads that meet project-specific requirements and align with sustainability goals.

What is Life Cycle Assessment?

Life Cycle Assessment (LCA) is a systematic process for quantifying the environmental impacts of a product, process, or service throughout its entire life cycle. This methodology can also be applied to linear infrastructure projects to assess the environmental impacts of road infrastructure construction throughout its entire service life. 

From raw material extraction to end-of-life, here are the different parts of the life cycle to consider:

• Raw material extraction (A1): It involves obtaining and preparing raw materials before manufacturing begins.
• Transportation (A2): The raw materials are transported to a production facility to manufacture end-products.
• Manufacturing (A3): The raw materials are turned into a finished product, ready for distribution. 
• Distribution (A4): The end-products are loaded into bags or bulk containers and transported to the construction site.
• Construction (A5): This stage includes all activities needed to construct the road physically, including material handling, machinery operations, and the installation of essential infrastructure.
• Use stages (B1-B7): This phase in road construction covers the road’s use, maintenance, repair, and refurbishment, including activities to ensure its functionality, longevity, and necessary upgrades throughout its operational life.

• End-of-life stages (C1-C4): They focus on the deconstruction, transport, waste processing, and disposal of road materials at the end of the road’s life, focusing on recycling and waste management.

LCA is a robust and trustworthy methodology. It relies on norms that define it:

• ISO 14040:2006: It describes the principles and framework for LCA.
• ISO 14044:2006: It provides the requirements and guidelines for LCA. It includes data quality, critical review, and reporting requirements. 

EN 15804 (Sustainability of Construction Works) frames the Life Cycle Assessment for construction materials, which is extremely important in the construction industry. It assesses the environmental performance of materials such as asphalt, concrete, steel, and projects (rails, roads, bridges…).

Find out more about LCA in this article:

What Is Life Cycle Assessment (LCA) in Linear Infrastructure?

What are the stages of LCA for your road construction project?

This section will discuss the different Life Cycle Assessment (LCA) stages involved in road construction. As about 90% of Europe's road network is surfaced with asphalt, this example will focus on flexible pavement. 

• The product phase that includes A1 to A3:

• • Raw material extraction: For flexible pavement construction, high-quality aggregates are sourced from quarries through drilling, blasting, and crushing. Bitumen, the key binding agent in asphalt, is derived from crude oil refining. Other materials, such as asphalt additives, might be required to manufacture the end products used for the different pavement layers. 
    
    

• • The transportation of raw materials to the asphalt plant involves loading, hauling, and unloading aggregates and bitumen using trucks or conveyors, ensuring efficient logistics and minimal material loss. 
    
    
  • Asphalt manufacturing involves heating aggregates, mixing them with bitumen at controlled temperatures, and adding performance-enhancing additives to produce a durable and workable mix.

• The construction phase with A4 & A5:

• • Transportation of the materials from the production facility to the construction site, including asphalt and the aggregates that compose the granular layers.
    
    
  • Construction and installation activities mainly involve asphalt laying and compaction after the granular layers that compose the foundation have been placed, compacted and leveled. Managing construction waste through proper transportation and disposal methods is also part of the construction activities.
  
  

LCA: Your roadmap for sustainable road infrastructure projects

Now that you have a general idea of what LCA is and the different stages of road construction, from A1 to A5, we’ll explore in more detail what needs to be considered to foster sustainability during construction.

A1 - Raw material extraction

At this step, material suppliers and designers should focus on:

• Using recycled materials whenever possible to promote a circular economy
• Using alternative materials

Many companies allocate resources to research and development (R&D) to discover innovative materials. This often involves partnering with universities or conducting in-house studies. For instance, bio-binders made from renewable sources like vegetable oils offer greater sustainability than petroleum-based binders, making them a more eco-friendly option.

A2 - Transporting raw materials for manufacturing

Transportation can also significantly impact the carbon footprint, so optimising the selection of locally available suppliers for the project reduces transportation distances. This reduces the cost and carbon footprint while maximising efficiency and promoting local economies.

A3 - Manufacturing

It is essential to monitor energy usage and emissions during material production. Selecting energy-efficient processes and exploring renewable energy sources can reduce environmental impact.

Material selection also considerably impacts the manufacturing process. Thanks to the additives used, Warm-Mix Asphalt (WMA) and Cold-Mix Asphalt (CMA) require lower heating temperatures than traditional Hot-Mix Asphalt (HMA). 

This reduces energy consumption during manufacturing, lowering the carbon footprint. However, the environmental impact of producing these additives must also be considered.

A4 - Transporting materials to their end location

As mentioned in A2, transportation can play a significant role in the carbon footprint, so sourcing from local suppliers is vital to minimise costs and carbon footprints.

A5 - Construction & installation activities

At this stage, efficient material management is essential to minimise waste and optimise resource usage. The construction process can be further enhanced through various strategies, such as:

• Using alternative fuels
• Reducing energy consumption by optimising idling time
  
  
  

Why is Life Cycle Assessment critical in road construction?

The road infrastructure industry is committed to being more responsible for the environment. This means it’s actively seeking solutions to reduce its carbon footprint and achieve decarbonisation in its operations.

Life Cycle Assessment (LCA) is an essential tool for advancing sustainable pavement designs. By incorporating LCA, stakeholders can make informed decisions based on a detailed understanding of the environmental impacts throughout the lifecycle of road construction.

For pavement engineers, who are tasked with designing the most efficient and durable solutions, LCA provides valuable insights into the following key areas: 

• • Identifying opportunities to reduce the carbon footprint, material waste, and resource consumption
  • Optimising road design for long-term performance, durability, and minimal environmental impact
  • Ensuring compliance with environmental regulations, such as the EU Green Deal and sustainability targets

With LCA as a guiding tool, engineers gain a robust framework for evaluating the environmental impact of each stage of their infrastructure projects, from materials sourcing to end-of-life disposal.

Deep dive into the role of LCA with our article:  What Is the Role of LCA in Linear Infrastructure?