Upgrade of N31

Building in confined space calls for good management.

A section of the N31 (Amsterdam – Leeuwarden) that runs through Harlingen is being reconstructed. We made the design and are building the road, including five viaducts and an aqueduct. The road is being widened to create a dual carriageway, much of which will now pass through a cutting five metres below ground level. This will remove it from view and allow Harlingen to be visually reconnected.

Many different specialisms are involved in this extremely diverse project. Our strength is that we have all the necessary specialists in-house. We are also used to managing all these disciplines to keep the work moving forward. The 60-metre-long railway viaduct that we slid into its permanent position in Harlingen in just six hours with the help of a sliding-track structure is a perfect example of this.

Building in a confined space

There is limited space for construction work and we are working in many different places at once. That complicates the project logistics. We are overcoming this issue by ensuring all activities are tightly controlled and by working smartly. At the same time, we have to allow traffic to continue to flow smoothly along this important artery. For that reason we are implementing the project in phases and constructing the new road alongside the existing one, where this is possible. Where the two overlap we are creating bypasses.  

Strong environmental focus

When you are working in a built-up area, good environmental management is essential. We have organised information evenings and “kitchen-table” sessions to involve local residents in the project. We have also visited schools to explain the dangers of construction traffic and highlight where construction vehicles will be travelling. Together with the measures we are taking in relation to the construction process itself, this is resulting in a high level of satisfaction within the local community. 



 Road infrastructure, Engineering works


 Directorate-General for Public Works and Water Management, Province of Friesland and Municipality of Harlingen


-€ 84 million

-5 viaducts and 1 aqueduct

-9,000 piles, 4,500 sheet piles

-340,000 m3 of ground excavated

-2 temporary bridges and 2 bypasses

Contract form

 Design & Construct






  • Construction
  • Specialties and Supply
Project Information

Project Phase: In progress

Construction Time: 2015 - 2017

Function category: Weginfrastructuur, Kunstwerken

Global Goals