You might hear the terms sustainable and green design used interchangeably. There’s enough overlap that they’re worth mentioning together.

Green design is one that seeks to do as little harm as possible to the environment, the landscape, human and animal health, and the surrounding air and water. It also entails choosing building materials according to their environmental impact. It considers the effect today, while sustainable design applies these concepts to longer-term thinking and economic planning.

Prioritizing low costs and quick development, and then failing to follow up with maintenance, results in higher infrastructure costsover the long term. Sustainable design will give us bridges that last longer and don’t cost as much to maintain. Since Europe has a long infrastructure to-do list, this is the perfect time to consider new design principles and materials.

A highway bridge collapse in Genoa, Italy, which killed dozens, occurred after years of warningsfrom concerned engineers.

A study in Francerevealed indicators of “strong deterioration” in the country’s networks of roads and bridges following years of underinvestment.

Germany hasn’t fared much better, with some architects going so far as saying the country’s bridges are rotting dangerously.

There is nothing sustainable about bridges that fail while they’re being used. Sustainability also cannot take hold while we’re building bridges out of materials that are resource-intensive to manufacture and practically designed to fail in a relatively short time.

What does a sustainable bridge design actually look like?

Greener Bridge Designs Coming to Market

We understand green design in general, but what does it mean for bridges? Here are the broad goals for green and sustainable design in bridge-building:

  • Whenever possible, green design should make a positive impact on the environment and enhance rather than detract from nature or our experience of it.
  • Sustainable and green bridges should use as few structures as possible to accomplish all the desired goals — such as combining pedestrian and vehicle bridges. Green bridges don’t use more land than is required.
  • Green bridges should be economical to operate, maintain and replace.
  • Sustainability should be taken into account throughout the bridge’s lifecycle: in how the materials are fabricated, how frequently replacement parts need to be transported to the site and whether the materials can be reclaimed after retirement.

A green bridge needs to permit convenient and efficient transport in addition to each of the goals outlined above. If you want to go a step further, it should be able to pay for itself and add additional value to the community — such as generating electricity through solar panels.

In one prime example of sustainable design, a team of designers gave the DSSH Pedestrian Bridgethe ability to generate its own power and clean its own air with a curated selection of plants.

The Scotney Bridge, on the A21 in England, is a picture-perfect example of building in a way that minimizes harm to the environment. The overpass is essentially a land bridge, which allows wildlife to cross the road safely and even provides nesting grounds for some species.

The Copenhagen Harbor LM Project spans two skyscrapers that use seawater to heat and cool the building.

North Carolina’s Linn Cove Viaduct, built in the late ’80s, is still hailed by some as one of the greenest bridge designsin the U.S. Its designers minimized impact on the environment from the earliest stages. The final design, which hovers well above the treetops, was cast in concrete in sections, then flown to the site. This eliminated ground-level construction and the need for temporary roads. Precast, prestressed concrete is also more durablethan structures poured on-site, which means they should outlast buildings built with less sustainable methods.

A team from Ohio accomplished an apparent first when it built a functional bridge out of 100% recycled plastic. According to WDTNTV, the composite bridge material was fashioned using previously used bottles, containers, car bumpers and dashboards. The resulting material won’t rot, splinter or rust — and that means it’s likely to outlast similar bridges using incumbent materials.

Two of these projects were born in America, but the United States’ failing grade on its infrastructure report cardindicates problems just like many European nations. This includes unsustainably designed bridges in increasingly dangerous states of disrepair.

The fact that so many different countries are staring down heavy infrastructure reinvestment price tags means now is a great time to rethink how we build them in the first place.

Megan Ray Nichols, Contributor