Rope drum for the Botlek Bridge

The Botlek vertical lift bridge is superlative in many ways—it is the heaviest lift bridge in the world, yet it has the greatest lift frequency and the fastest lift speed.

We manufactured the components at the heart of the lifting movement system—a total of 16 rope drums. The technical specifications of this project required extraordinary solutions: the two spans of the bridge are each 90 metres long and 50 metres wide, and the lift weight of each span is 4,850 tonnes—together, these weigh almost as much as the whole Eiffel Tower (10,000 tonnes)! The mass to be moved is impressive, but so is the frequency of the openings.

The bridge is opened approx. once per hour, which means 9,000 openings per year. The assembly of the mountings and the application of the 4x35 metres of rope per drum were also part of this consignment. Reliability and a long operational life despite harsh environmental conditions were among the most important requirements which each individual part had to fulfil. To achieve this, we applied our comprehensive manufacturing know-how to every one of the bridge components throughout the entire production process.


  • Shafts: S500Q fine-grained construction steel, welding filler material with acceptance test certificate (APZ 3.2)
  • Drums: S355J2+N with acceptance test certificate (APZ 3.2)
  • Welding filler material with acceptance test certificate (APZ 3.2)
  • Welding in accordance with EN1090-2EXC3
  • Temperature-controlled welding
  • Stress-free annealing with heat treatment record
  • UT ultrasonic testing in accordance with EN ISO 17640 Level C


  • Milling the rope running grooves
  • Shaft interlocking W500x8x61x9c DIN 5480


  • Coating: C5-I/M very high (sea water and fresh water-resistant)
  • Rope groove: induction-hardened to 320-420 HB, surface hardening depth: approx. 2 mm


  • Mounting the bearings
  • Winding on the ropes

Quality Assurance

  • 3.2 material certificate
  • Detailed documentation
  • ITP (inspection-test-plan) of the customer