Construction of cable section between two high-voltage substations
138 km of cables for a 150 kV connection
Anyone who regularly drives along the A4 and A5 past Schiphol will certainly have noticed our works. On 1 April 2024, following the completion of the engineering phase, we started work on-site to construct the access roads and install a total of 44 directional drillings, allowing us to pass all obstacles around Schiphol underground. The section largely follows the A5 and crosses the A4.
44 directional drillings for the casing pipes
The construction of these HDD boreholes was necessary to connect the new Rozenburg Zuid high-voltage substation, with 138 km of high-voltage cables, between the existing high-voltage substations at Vijfhuizen and Nieuwe Meer to the high-voltage grid operated by TenneT.
At the time of writing, almost all of the drilling has been completed and the enormous reels are being delivered by special road transport and unwound. To allow the ‘train’ of HDD installation work – pulling the cable strands into the casing pipes and fitting the joints – to continue, kilometres of access roads have been constructed over a distance of 12 km in the Haarlemmermeer. It is expected that by the end of 2025, all cables will have been pulled in, connected and tested so that the new high-voltage substation can be commissioned in 2026.
Challenging execution
To ensure that all of this work is carried out efficiently within a tight execution schedule, there are weekly meetings between all contractors involved: Hanab Energy Solutions, Hanab Drilling, supplier Prysmian (which supplies and installs the cables), Vilsteren (which is carrying out the civil engineering works) and Van Kessel Bronbemaling (which is keeping the trenches dry).
The history of this project goes back a long way. Due to the increasing demand for electricity around Schiphol, TenneT needs to significantly expand its network. We signed an agreement with TenneT in early 2021 to construct a 12 km double-circuit 150 kV connection plus a further 3.5 km double circuit between the Vijfhuizen and Nieuwe Meer high-voltage substations. The agreement included an option to construct a further four circuits, each 12 km long, between Raasdorp and Rozenburg Zuid. Thanks to successful collaboration and timely completion, TenneT has opted to extend the collaboration.