The Netherlands used 50 ecoduct bridges to solve habitat isolation across a 400km highway network; the result transformed divided forests into contiguous wildlife zones

The Netherlands used 50 ecoduct bridges to solve habitat isolation across a 400km highway network by creating links between nature areas separated by roads and other infrastructure. The country has built more than 600 wildlife crossings, including over 50 large ecoducts, to help animals move between habitats. These structures form part of a wider approach to reconnect nature. Roads can divide forests and other ecosystems into smaller areas. This can limit movement, reduce access to food and increase the risk of animals being hit by vehicles. Wildlife bridges provide a route over roads while keeping transport routes open for motorists.

How roads divided natural habitats?

Transport infrastructure can create barriers inside nature areas. Motorways, railways and canals can divide forests, heathland and grasslands. When natural areas become smaller and separated, animals may have fewer places to find food and shelter.


Small and isolated animal populations can also face inbreeding. When animals cannot reach other groups, opportunities for genetic exchange are reduced. Movement between different habitats is therefore important for maintaining animal populations.

Animals that try to cross roads can also face collisions with vehicles. This creates a risk for wildlife and can create safety concerns for drivers. In a natural system, animals move between forests, heathland, grasslands and waterways. Wildlife crossings are designed to restore some of that movement after transport infrastructure has divided the landscape.

The Netherlands built a network of wildlife crossings

The country has developed more than 600 wildlife crossings. More than 50 of these are large ecoducts, also known as wildlife bridges or green overpasses. These crossings are part of a wider habitat defragmentation effort. The goal is to connect natural areas that had become separated by roads and other infrastructure.

The approach also forms part of the Netherlands National Nature Network. Earlier known as the Ecological Main Structure, the network was first published in 1990. Its purpose was to address the loss of nature and biodiversity. The plan called for nature areas to be connected more effectively and expanded where possible.

From 2004 to 2018, many ecoducts were built through the Multiyear Habitat Defragmentation Programme. Rijkswaterstaat, ProRail and the provinces were involved in the programme.

The Netherlands used 50 ecoduct bridges to reconnect habitats

Ecoducts allow animals to cross transport routes without entering traffic lanes. Vegetation and soil can be placed on top of these structures, creating a route that resembles the surrounding landscape.

The crossings can support species that need to move between separate natural areas. Red deer, wild boars and badgers are among the animals that can benefit from connected habitats.

The crossings can also help reduce wildlife-vehicle collisions. Instead of crossing a motorway at ground level, animals can use a dedicated route above it. This creates two separate functions. Vehicles continue to use the road below, while animals use the crossing above.

Woeste Hoeve is one of the early ecoducts

The Woeste Hoeve ecoduct is on the A50 motorway between Arnhem and Apeldoorn. It was opened in 1988 and was among the first two ecoducts in the Netherlands. The structure was initially designed mainly to allow red deer to cross the motorway. It now connects two nature reserves.

The ecoduct is a nature bridge. Although it may look like a tunnel from some viewpoints, it is essentially a viaduct that allows wildlife to travel over the road. The crossing has a 50-metre-wide span. Funnel-shaped grids on both sides guide animals towards the crossing.

Shrubs and trees have been planted along the edges. These plants help reduce the effects of light and noise from the motorway. A layer of soil between two and three metres thick was placed on the span. This helps limit noise penetration and provides the material needed for trees and shrubs to grow.

How the structure works?

The design of Woeste Hoeve uses slopes leading towards the structure. The tunnel tubes were built at the same gradient. From the road, this can make it appear that motorists are entering the ground. In reality, they are travelling through an opening created in an earth wall.

The structure includes three passages made from corrugated sheets supported by a concrete base. The two passages for the motorway are about 16 metres wide and eight metres high. A separate passage for a local road measures about 12 metres by 6.5 metres. Together, these elements allow the transport network and wildlife routes to operate in the same location.

The crossings support movement and genetic exchange

Habitat connectivity is important because animal populations need access to different areas. A forest divided by a motorway can leave animals with fewer options for movement. When areas are connected, animals can travel between them in search of food and suitable habitat. Movement also creates opportunities for animals from different populations to interact.

This can support genetic exchange. The issue is important for species living in areas that are too small to support healthy populations on their own. The same principle applies to migration. Wildlife needs routes between habitats, especially when roads and other infrastructure have changed the landscape.

Natuurbrug Zanderij Crailoo spans 800 metres

The Netherlands is also home to Natuurbrug Zanderij Crailoo, described as the world's longest wildlife crossing. The structure stretches about 800 metres. It crosses a railway line, a major roadway and a golf course.

The crossing shows how wildlife infrastructure can be incorporated into areas containing several types of human development. Rather than creating one narrow passage across one road, the structure provides a wider connection across several barriers.

Research is being used to improve wildlife crossings

The Netherlands now has around 80 nature-friendly structures such as ecoducts. Managing these structures involves both infrastructure and nature conservation authorities.

The viaduct itself is mainly managed as infrastructure, while the local nature conservation authority usually manages the vegetation. Vegetation can take several years to develop. Because of this, managers need to assess the site over time and determine whether changes are required.

Dutch organisations also work with international networks and knowledge institutes to study which types of passages work for different species. Research indicates that ecoducts can be suitable for many species. However, they are not a universal solution for every location.

Cost remains an important consideration

Wildlife bridges require significant construction resources. Their cost means that each location needs to be assessed before a solution is selected. The objective is to identify the best way to address a particular bottleneck between nature and roads.

An ecoduct may be suitable in one location, while another site may require a different type of crossing. The choice also needs to consider the species using the area, the road layout, the surrounding landscape and the risks created by the existing barrier.

The Netherlands' habitat defragmentation programme shows how wildlife movement can be included in transport planning. More than 600 crossings, including over 50 ecoducts, have created routes through a landscape where roads, railways and canals divide natural areas.

The Woeste Hoeve ecoduct is one example. Opened in 1988, it was first intended mainly for red deer and now connects two nature reserves. The wider network is designed to reduce habitat isolation, support animal movement and lower the risk of road collisions.