What can we do to improve pavement sustainability?

What can we do to improve pavement sustainability?

There are many opportunities for implementing sustainable practices in a pavement’s life cycle. The pavement life cycle includes the material production, design, construction (which includes new construction as well as preservation, maintenance, and rehabilitation), use, and end-of-life stages.

1) Materials

A range of material, mainly aggregates, asphalt materials, and cement materials, can be used for paving. A well-known approach to using sustainable pavement materials is using recycled, co-products or waste materials. Other approaches are available, and there are emerging technologies to monitor that can improve pavement sustainability in terms of aggregate production, asphalt and concrete materials. Each approach should be evaluated from a life-cycle perspective to understand how it contributes to the sustainability of a pavement system. This enables you to examine the possible economic, environmental, and social impacts throughout the life cycle, as well as the potential trade-offs.

2) Design

The design process should focus on developing alternative pavement structures (including structural layers and thicknesses), specifications for materials that meet the performance objectives of the individual layers as well as the system as a whole, with consideration of subsurface drainage (if appropriate), and monitoring construction specifications for the pavement to perform as expected.

It is important that sustainability is considered when defining the project objectives. However, trade-offs should be carefully considered, as improvements in one area might be detrimental to another. Examples of sustainable pavement strategies can include: longer life pavements, designs incorporating local materials to reduce transportation costs, accelerated construction materials, and single lane rehabilitation.

3) Construction

New construction techniques and technologies in conjunction with appropriate pavement structural designs that use appropriate materials can greatly contribute to overall sustainability of a pavement system. A range of software tools are available to support the sustainability of pavement construction operations.

4) Use

The impact from usage largely relies on vehicle operations and its effect on the pavement and the environment. Several pavement characteristics have been linked to various use stage impacts such as  vehicle fuel consumption, noise, safety, stormwater runoff, and the urban and global climate. Some decisions regarding usage can be made at the network level and may be implemented through pavement management systems, while others can only be applied at the project level through design and construction decisions.

There are trade-offs that may need to be considered within these decisions including important safety issues. Many of these trade-offs are dependent on project context, especially in relation to traffic levels and climate. Project context also often has a large influence on the importance of environmental impacts of different phases of the pavement life cycle. For example, use-phase impacts on routes with heavy traffic are often much bigger than material production and construction phase impacts, while the opposite may be the case for low-traffic routes.

5) Maintenance and Preservation

Pavement preservation utilises low-cost treatments to prolong pavement life by delaying the need for major rehabilitation. This saves on energy and virgin materials while limiting the amount of emissions over the life cycle. Well-maintained pavements offer smoother, safer, and quieter riding surfaces over a large portion of their lives, and this results in higher vehicle fuel efficiencies, reduced crash rates, and lower noise impacts on locals, which contributes to their overall sustainability.

6) End-of-Life

At the end of a pavement's life, the pavement may (1) remain in place and be reused as part of the new pavement, (2) recycled, or (3) be removed and landfilled. Ensure that the economic and environmental costs of these activities are evaluated.

Conclusion

There are many opportunities throughout the pavement’s lifecycle in which we can make good choices for our planet. This starts from the very beginning when we make the materials, to when we build the road, to when we use it, to when it's time to remove it. So, let's work together to make sure we're taking care of the earth every step of the way!

Reference

FHWA, 2022, ‘Sustainability Pavement Program’, viewed on 14 November 2022. Available at <https://www.fhwa.dot.gov/pavement/sustainability/what.cfm>