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Green bridges as ecological stepping stones

Sarah Kydd | 30 Mar 2016 | Comments

The construction of linear transport infrastructure projects can often negatively impact wildlife through the loss of connectivity between habitats. This reduces options for foraging, breeding and nesting, with small isolated patches of land able to support fewer individuals.

I recently carried out research, in partnership with Natural England, exploring the effectiveness of green bridges in mitigating against the various negative impacts of transport infrastructure on wildlife. The study found that green bridges do successfully provide an innovative solution to help mitigate against these negative impacts. These bridges, planted with native trees and plants, can be used by wildlife as crossing points between habitats and even as a place to live. Beyond the benefits for wildlife, green bridges can also be used to visually integrate roads and railways into the surrounding landscape, as well as provide access for communities to the wider countryside. Through creating high quality, visually attractive crossings for pedestrians, cyclists and horse riders, green bridges can encourage more people to use these routes, resulting in health and wellbeing benefits.

Within Europe, the Netherlands is a leader in developing a green bridge network, with over 40 such structures across the country. The Terlet, one of the country’s first green bridges to be constructed, is being used by a range of species as a crossing over the busy road and a corridor between the two habitats either side. Badgers, red deer, roe deer, fallow deer, wild boar and foxes have all been recorded on the structure.

But green bridges don’t just have environmental benefits. One of the first green bridges built within the UK was created for heritage reasons. This was Scotney Bridge on the A21, where the dual carriageway was severing an import historic driveway. This route has been preserved as a result of the bridge and there have also been found to be wider ecological benefits, with dormice nesting on the bridge itself and bats flying over it.

The benefits of green bridges are widely accepted and the structures are a common feature across Europe’s road and rail infrastructure. However, they are still few and far between within the UK and I believe we should be doing more to utilise their benefits. We need to start considering green bridges from the outset when designing major new infrastructure schemes, undertaking screening to identify negative environmental impacts and determine whether these could be mitigated against through the creation of a green bridge. I believe this is particularly important when looking at infrastructure projects within sensitive areas such as National Parks and Areas of Outstanding Natural Beauty.

At Atkins we have already started to lead the way in the design of these structures through our involvement in projects such as HS2, where a number of bridges are being adapted to provide green benefits. With the combined skills of our engineering teams, working with our ecologists and landscape architects, we can help our clients to become pioneers in bringing green bridges to the UK and promoting their virtues for the wide ranging environment and community benefits they can provide.