More space for mobility and nature on the A9BAHO

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Rijkswaterstaat is widening the motorways between Schiphol, Amsterdam and Almere by adding more lanes. This will improve the traffic flow and accessibility of the northern Randstad. The A9 between Badhoevedorp and Holendrecht (A9BAHO) is the fifth and final section. Rijkswaterstaat and Witteveen+Bos are jointly responsible for the technical coordination and engineering, working in close collaboration with Oxand. The reconstruction of the A9BAHO has been seized upon to create significantly more space for nature.

‘At Witteveen+Bos, we saw opportunities to do more for biodiversity at an early stage. In addition to our evaluative role, we translated this into action by looking for promising locations and ways of integrating nature, drawing on the knowledge of ecologists within our own organisation,’ says Savimby Augustuszoon, structural engineer and project manager. ‘Rijkswaterstaat was very enthusiastic and added a new point of attention.’

Factor of four

Once the go-ahead had been given, a considerable amount of time was invested in overcoming organisational, communication and technical hurdles with stakeholders such as the municipalities and the province. And also within the project team, coordinating between ecologists and infrastructure experts at Rijkswaterstaat. ‘All our efforts have not been in vain: we have succeeded in creating nature-friendly banks.’ The original requirements of the contract have been exceeded by a factor of four; a total of 2.8 kilometres of nature-friendly banks will be created.

This involves converting ditches into nature-friendly banks. Thanks to their gradual superelevation, these banks provide a natural transition from water to land, improving water quality and creating favourable conditions for various habitats. This benefits aquatic fauna such as ring snakes, frogs, newts, dragonflies, fish and aquatic plants.

A lot of potential

Annelies van de Craats is an ecologist at Witteveen+Bos and has extensive experience with similar projects. ‘Ditches running alongside infrastructure offer a lot of potential for creating nature and improving water quality. These are often ditches that do not border agricultural land and are therefore not fertilised. The lack of phosphate load means there’s a lot of potential for healthy water.’

For the A9BAHO, we have been able to incorporate new and current insights and ambitions for biodiversity within the ongoing project. ‘We hope that the addition of nature-friendly banks will inspire other ongoing infrastructure replacement and renovation projects to raise their biodiversity ambitions,’ says Savimby Augustuszoon. ‘Follow-up discussions are currently underway to see if there are further opportunities to boost biodiversity in the current phase of the project.’

Annelies van de Craats adds: ‘The fact that nature-friendly banks have been incorporated into this ongoing project proves that it is possible to create extra space for nature on existing sections – if stakeholders want to make a difference. It is encouraging to see that clients are willing to adapt to the needs of the times.’

Witteveen+Bos wants to play a proactive role in this topic. As an organisation, we have set ourselves the task of working with our clients to promote climate-neutral practices and improve biodiversity within projects.