Renovated Zelzate bridge ensures continuation of shipping on Ghent-Terneuzen canal

Zelzate bridge

The Ghent-Terneuzen Canal connects Ghent to the Westerschelde, a direct connection to the North Sea. The canal is vital to the economy of Ghent. The canal divides the municipality of Zelzate. Both parts of the municipality are connected by the Zelzate bridge, one of Belgium’s largest drawbridges, and by the Zelzate tunnel.

Modernization necessary for the continuation of shipping

In 2008 the electromechanical equipment of the bridge was more than 20 years old, some parts more than 40 years old. The age of the equipment contributed to more and more defects. Given the importance of the bridge for shipping and the road, it was essential that the bridge operated reliably.

Most importantly of all, the bridge no longer met necessary safety standards. That is why the Flemish Road and Traffic agency decided to fully renew the electromechanical equipment in order to meet current standards. Agidens won the contract to carry out this job at a value of € 3,800,000. Agidens selected Bosch Rexroth for the hydraulic system, Vandezande for the mechanical parts and RDM Smeertechnieken for the renewal of the automatic lubrication system.


The job consisted of the renewal of the existing electromechanical equipment of the Zelzate Bridge

Fully redundant PLC control with plcs for the control of the critical technical steering locks.

Fully redundant glass-fibre ring between the control tower and both of the bridge cellars. Separate section (1 glass-fibre ring via the underwater crossing, 1 glass-fibre ring via the Zelzate tunnel).

Redundant SCADA operation to replace the old operation desk.

Renewal of the existing power plant in the existing control building (left side of the Zelzate Canal) for energy supply for the control building and for supplying the left-hand side of the bridge and its systems.

New power plant for the right-hand side of the Zelzate canal for the energy supply of the right side of the bridge and its systems.

Disassembly of the old relay room for the control of both sides of the bridge.

New low-voltage control panels and general service signs in each bridge cellar for the control of the corresponding side of the bridge and its existing locks and systems.

Full renewal of the shipping signalling system (replacement of the old coil signals with LED signals).

Renewal of the hydraulic system of the drawbridge mechanism (excluding the drawbridge cylinders.

Full renewal of the mechanical and hydraulic system for locking under the counterweight.

Full renewal of the mechanical and hydraulic system for locking (clamping) on the front of each of the 2 sides of the bridge.

Renewal of the whole lubrication system.

Redundant versions ensure continuous operation

The control is composed of a double redundant glass fibre-ring between the respective bridge cellars and the control building. The control sequence that allows both sides of the bridge to fold synchronously is carried out by a hot redundant Schneider Premium PLC set-up in the control building. In both bridge cellars there is an identical PLC set-up that is responsible for controlling the technologies.

The bridge’s safety latches are monitored by one hot redundant PLC per bridge cellar. The higher-level Vijeo Citect Scada-software is redundant in the control tower. In each bridge cellar a SCADA set-up has been provided for maintenance.

Limited obstruction for road and shipping traffic

The biggest challenge of this project was undoubtedly the requirement that the bridge could only be out of use for 6 weeks for road traffic, and that a limited amount of shipping traffic was still to be allowed through during this time. The nature of the mechanical work meant that the drawbridge could not lock during this period and it remained in an upright position. The bridge needed to be able to move during the electromechanical conversion.

Faster, more reliable and maintenance-friendly bridge

The new control system and operation of the bridge are extremely reliable. This a great added benefit to the customer, both in terms of reliability and efficiency. Due to the rapid start-up of the plant and faster sequences of control actions, waiting time for road traffic users has been significantly reduced. Thanks to the extensive monitoring and data capture techniques, the technologies can be better monitored in the maintenance module. If there is a problem, it can be diagnosed much more quickly and this limits reaction time.