Unusual opening bridge
The construction is a movable bridge with a span of 68 meters, which opens like a bascule bridge. However, this bridge does not have an unlimited headroom, the bridge only lifts 18 meters at the tip, which is lifted directly by a huge hydraulic ram. Usually with a bascule bridge, lifting equipment is placed at the pivot point and a significant counterweight is required. At the GWRB, the span is too large for this type of bascule bridge, and there is no space for the counterweights.
Orthotropic deck construction
The bridge consists of two main girders with an orthotropic deck construction in between. The main girders are constructed as a “Vierendeel truss” with a curved upper cord, which is trapezoidal in section, narrowing and deeper towards the top of the arch. The top string of the truss is thick section to get stiffness, while to minimize weight, the thickness of the deck’s steel plate has been kept at a slim 12mm. The telescopic ram exerts a thrust of 650 tons and will reach full extension up to 18 meters. At that position there is a sailing area of 15 by 15 meters.
Manufacture & installation
The bridge was made in four parts at the yard at Hollandia in Krimpen aan den IJssel; 2 end parts and 2 middle parts. These sections were brought to the site on pontoon in 3 shipments. The end sections are placed and secured on the abutments. Then the joined center section has been positioned and installed by means of beach jacks. Finally, the bridge sections were joined, blasted and painted.