BESIX Unitec is upgrading a 1.89-km rail tunnel in Best, between Boxtel and Eindhoven, to meet ProRail’s current tunnel standard. The project includes major upgrades to the tunnel’s control and safety systems. BESIX Unitec is also testing what it takes to carry out the work emission-free under real project conditions.
From tender commitment to execution
The project was awarded using the CO2 Performance Ladder, a procurement instrument that rewards bidders for their climate ambition. BESIX Unitec tendered at the highest level, giving its bid a 10% notional discount for evaluation purposes.
That commitment translated directly into the project’s execution. All equipment used by the team, whether owned or hired, was electric. The equipment was also transported electrically from the BESIX site in Schelle to the project location.
Lessons learned
Electrifying the worksite addressed operational emissions, but not the emissions associated with producing the materials used on the project. The team proposed reusing existing control cabinets and supporting structures, although this option was not taken forward by the client. Cable trays could be reused where possible.
Using electric equipment under real project conditions also gave the team a clearer view of the practical requirements. Reliable access to sufficient electricity is essential, and electrification has to be considered from the planning stage rather than added later. These lessons can now feed into future project preparations and discussions with clients.
“With this project, we are showing clients and the market that emission-free execution is possible in a competitive way, without compromising quality or efficiency,” says Rob Petie, Operations Manager at BESIX Unitec NL.
Building experience across projects
BESIX Unitec, BESIX Unitec NL, BESIX Infra and BESIX Connect have held level 5 certification under the CO2 Performance Ladder since 2022. In 2026, BESIX Unitec NL and BESIX Infra have seven projects underway or awarded in which reducing CO2 emissions through the CO2 Performance Ladder forms part of the contract.
The Best tunnel shows what that commitment means in practice: electrification brings specific operational requirements, while opportunities for reuse may depend on decisions beyond the contractor’s control. More importantly, the experience gives future teams a stronger basis for planning emission-free works and discussing the necessary conditions with clients from the outset.
Read more about projects with a CO2-related advantage.
