Going green has become a fact of life. For decades, the world has been moving toward solutions that are environmentally friendly and sustainable. This has affected everything from the foods we eat to the vehicles we drive to how the power that runs our lives is generated.
It has also significantly impacted how bridges and related infrastructure elements are designed, built, maintained, decommissioned, and replaced.
In this article, we’ll explain the basic concepts of green and sustainable design. We’ll explore some of the issues that must be dealt with — and questions that should be answered — when applying them to bridge-related projects. We’ll also look at some innovative green and sustainable bridges that will provide inspiration on how you can take your projects to the next level.
Snapshot: Recycled bridge, Logan County, Ohio
It may not look like much, but this bridge, completed in 2012, was built out of a 100-percent recycled plastic material called STRUXURE. It is made from 80 percent post-consumer plastic (including bottles and other containers) and 20 percent recycled car bumpers and dashboards.
This bridge is currently the longest recycled plastic bridge serving the public in the United States. It is likely that it will outperform comparable structures built with traditional materials because it won’t rust, splinter, crumble, rot, absorb moisture, or release chemicals into the environment.
Definitions of green and sustainable bridge design
Green and sustainable bridge design means different things to different people, companies, and agencies. In addition to the basics of being safe and efficient, they can also incorporate a wide array of climate mitigation and adaptation, resilient infrastructure, asset management, and environmental objectives.
Many people use the terms “green design” and “sustainable design” interchangeably. They are two different things, however, and both must be leveraged on projects to be effective.
- Green design, often referred to as green architecture, is an approach to building bridges and other structures that minimizes harmful effects on the environment and human health and well-being. The architect or designer takes extra steps to protect the air, water, earth, humans, and wildlife by choosing eco-friendly building materials and using construction practices that minimize environmental and human health impact.
- Sustainable design, also referred to as environmental design, environmentally sustainable design, or environmentally conscious design, is a design philosophy that focuses on social, economic, and ecological
Green design focuses on protecting the environment and the health of humans and wildlife in the present.
Sustainable design goes a step beyond and considers the long-term impact on these things, along with the economic aspects, to ensure that the positive benefits can be maintained over the long term.
This is a huge paradigm shift from bridge construction practices in previous decades, which often focused on fast development and low cost. The highway and bridge construction boom that took place in the middle of the last century is a perfect example of this.
- The development during that period often lead to significant environmental issues at the time of construction and for decades after. Natural environments were paved over or polluted, and native species were banished.
- The maintenance costs of these inexpensively built structures have been burdensome over time.
- Today, these bridges are having another big impact on humans, wildlife, the environment, and economy because they need to be destroyed and replaced after only 50 or 60 years in use.
Shifting away from this negative cycle to one that is “greener” to start and “more sustainable” over time will have a positive influence on people, the natural environment, and the economy for decades and centuries to come.
Snapshot: Dynamic Shape Shifting Helix (DSSH) Bridge, Montreal, Canada
This flashy pedestrian bridge may not seem like an obvious example of a green or sustainable structure — especially when it is illuminated at night.
However, the amazing light show that brings it to life at night is powered by photovoltaic solar panels that generate clean energy during the day. The LED lighting system limits energy use. Green plants have been included in the structure to help provide and circulate fresh oxygen and eliminate pollution. Recycled products were also used in the building process.
Principles of green and sustainable design
Most experts agree that the following concepts should be addressed when developing a green and sustainable bridge project:
- At its most basic, it must allow individuals, vehicles, and utility infrastructure to cross expanses in a safe and efficient way.
- If possible, it should make a positive impact on the environment, the community surrounding it, and the people who experience it.
- It supports multiple forms of transportation (if needed by the local community) in an efficient way. (It should avoid the need to develop multiple structures to support different types of vehicles, such as bicycles, cars, and trains. It should also incorporate other uses, including utility transport, when possible.)
- It must keep the ecological balance within the planet’s ability to absorb its consumption of non-renewable resources and emission of waste.
- It should limit use of land and affect on the natural environment, including its potential impact on climate change.
- Environmental issues should be considered throughout its lifespan: during the construction process, while it is in use and being maintained, and finally, when it is replaced or demolished.
- It must be affordable to build, operate, maintain, repair, and replace.
- The bridge should sustain itself economically and potentially generate revenue for its owner and the community surrounding it.
Snapshot: Proposed Meadow Bridge, Salford, United Kingdom
This bridge design recently won a competition for a structure in a natural landscape in the United Kingdom.
The shape of the bridge echoes the curved land, river, and pathways nearby. It sensitively connects meadowland with an urban environment.
The design goes above and beyond by creating a new public space with wildflower mounds and seating that brings the meadow into the urban environment. In addition, the crown of the arch offers a place to rest and look out at unique views of the river valley below.
Designing for Sustainability and Resilience
Sustainable bridge design requires architects and engineers to think broadly and deeply about their projects.
All phases must be evaluated during the planning process to ensure it is fully green and sustainable over time, including:
- Repair and rehabilitation.
- Final decommissioning.
- Disposal and replacement.
Green and sustainable design does not simply involve minimizing how a bridge integrates into its natural environment but also ensuring that it functions and performs in an efficient way, limiting the impact it has on the natural environment and climate, and controlling the affect it has as it serves its ongoing function of allowing people, vehicles, and utilities to cross spaces and distances.
It should also go deeper and consider things like how it:
- Integrates into the broader natural and urban infrastructure.
- Impacts communities and the people who live in them.
- Affects society.
- Limits or enhances biodiversity.
- Affects maintenance costs over time.
- Limits impact to future climate change.
- Adapts to future changes in climate.
- Considers the impact it could have on the environment, society, and the economy throughout its life.
In other words, a bridge can’t just be designed for today. It must be built to address all these issues for years, decades, and centuries to come.
Snapshot: Linn Cove Viaduct, North Carolina
This concrete segmental bridge travels around Grandfather Mountain in North Carolina. Even though it was completed in 1987, it is still considered one of the greenest bridge construction projects in history. It was also one of the most challenging to build as well.
The structure was designed to minimize the damage a traditional cut-and-fill road would have caused to this extraordinary natural environment.
Held up by seven large pillars, the viaduct essentially floats in the air without disturbing the land below. To eliminate damage to the environment, no access roads were built for transporting heavy equipment to the construction site. The bridge’s segments were built at a factory and moved to the bridge site. Each section was lowered into place by a crane placed on either edge of the existing structure, preventing any damage to the landscape.
The only construction that occurred at ground level was drilling the foundations for the seven permanent piers that support the structure.
Here are some questions you should ask yourself as you think about building a green, sustainable bridge.
|Environmental impacts||Benefits for society||Economic benefits||Future issues|
|What impact will it have on native plants and animals?||What can I do to improve how the local community engages with the structure?||Will this structure cost more than the revenue it is able to generate?||How can I protect utility infrastructure and other vulnerable components against future environmental issues, including more extreme weather?|
|How will it affect the globe more broadly?||Does this design bring joy and delight to people who experience it?||What green and efficient technologies can I leverage that will lower construction and maintenance costs?||Is this a bridge that will last 100, 200, or even 1,000 years?|
|How can I more seamlessly and effectively integrate utility infrastructure so it doesn’t have to be placed elsewhere?||How will this structure affect the health of people in the area and beyond (example: downriver)?||What can be done to limit the cost of land that must be purchased and owned to complete the project?||Will the design keep people safe now and when “safety” could mean different things in the future?|
|Am I doing all I can to limit the affect of stormwater and other runoff?||Are you using modern techniques to keep people safe?||How can the project benefit local businesses?||Is there a plan for sensibly and sensitively taking down the bridge?|
|What can I do to limit environmental impact during construction?||Will the design — and the business plan behind it — increase taxes or generate positive economic benefits?||Is there a more cost-effective way to do this?||How will potential emergencies be handled in an environmentally friendly way?|
|What steps can I take to better manage construction waste?||Are you involving local people in the design? Have you asked what’s important to them?||Have I done everything possible to avoid environmental penalties and fees?||Is the project adaptable enough to evolve as its community changes over the next decades and centuries? Will it be able to handle future transportation needs?|
|What materials can I use that are most environmentally friendly, including pieces from older bridges and other structures?||How does the design connect with other local infrastructure?||Have I completely leveraged the information provided in the economic analysis?||Will this structure be considered “green” years from now?|
|What steps can I take to reduce, recycle, and re-use?||What affect will the design have on commute and transportation time?||Is there any way to incorporate faster or more efficient construction techniques?||Is the bridge adaptable to future utility generation and transmission needs?|
|How can I limit energy use and emissions during construction and beyond?||Is everything possible being done from a design perspective to limit the impact maintenance will have on traffic?||Can I use systems that will make ongoing maintenance easier and cheaper?||Will the bridge be able to easily incorporate tech advances in the future?|
|How can I reduce noise?||How soon will the community need to experience the disruption of replacing the bridge?||Does the design allow for use of modern, efficient bridge maintenance equipment?||What will the future look like, and how will this bridge fit into it?|
|What can I do to make the bridge more resilient and longer lasting so it can better withstand storms and extreme weather?||What more can I do to make this structure a great experience when people are on it or looking at it?||Is utility and other infrastructure being integrated in the most cost-effective and efficient way possible?||Will people love this structure 100 or 1,000 years from now? Will they fight to preserve it?|
Needless to say, bridge designers, engineers, and maintenance workers have been leveraging green, sustainable practices for decades. These include things like taking advantage of rapid construction methods, using pre-fabricated components and recycled or reused materials, and planning for extended service life through more thoughtful and durable designs.
However, that is only the beginning. This effort can go so much further by doing things like designing structures and selecting materials based on a bridge’s potential life (centuries versus decades), considering long-term economic and environmental costs rather than immediate benefits, using innovative materials and technologies, being more collaborative during the design and construction processes, and actually thinking about how a bridge can bring lifestyle benefits — and maybe even delight — to its community.
This may seem like a big leap, but it is already being done throughout the world, and there’s no reason you shouldn’t be doing it too.
Snapshot: Wildlife bridge, The Netherlands
Collisions with vehicles take the lives of countless animals every year, especially in areas where roads cut across nature habitats. Many people are injured in these accidents as well.
The solution: Wildlife crossings allow land-based creatures to pass from one side of a road to the other. An added benefit: They’re green, and most are designed to be highly sustainable.
A particularly beautiful — and functional — example is the Ecoduct De Woeste Hoeve. It was designed to protect red deer, badgers, and ermine.