Six temporary bridges increase construction site accessibility

To increase accessibility to the immense construction site of the A24 Blankenburg connection, construction consortium BAAK is using six temporary bridges from Retro Bridge. The specialist in temporary bridges has more than 15,000 tons of bridge elements in its 'pool' and was therefore able to switch in a relatively short period of time. There was only a few months between order and assembly, according to Retro Bridge's general manager Han Kastermans.

The initial request involved the delivery of four temporary bridges, one over Droespolderweg (RLB bridge), one over Maassluissedijk (RLB bridge) and two over Kistdam, both an RLB and an RBB bridge. "Because the period of use is longer than plus-minus three years, BAAK chose to buy these bridges with the option of buying them back during normal use. After all, that is more advantageous," Kastermans says. "At a later stage, we delivered two more rental bridges in the form of an RBB bridge over a tunnel compartment and an RFB pedestrian bridge at the Holland Tunnel."

Modular bridge concept

The big advantage of Retro Bridge's temporary bridges is their easy assembly on site. "We prepare the bridge strands completely in our workshop to a length of up to 40.5 meters and then hoist them into place on site with a crane and connect them together," Kastermans explains. "We didn't spend more than three-quarters of a day assembling each bridge." The longest bridge here on the Blankenburg connection is the RLB bridge over the Kistdam with a length of 37.5 meters. That was not the original length, by the way. "We initially delivered the bridge in strands of 24 meters. With time, the construction pit became larger, and that required a larger span. So the bridge was 'lifted' with elements of 13.5 meters in length. That too is no problem with our modular concept."

BIM model

Retro Bridge uses several variants of the modular bridge concept. "With our standard range of RLB and RBB bridges, we can achieve a span of 37.5 meters in accordance with the maximum mobile load in the Eurocode," says Kastermans. "And with the RFB pedestrian bridge, we even achieve a free span of up to 57 meters. Usually we draw from our large stock, but because we also had to supply the Groene Boog and the Linkeroever in Antwerp at the same time as the Blankenburg connection, we made four bridge strands new. Construction consortium BAAK, by the way, had its affairs in good order. Via the BIM model, we could see in advance exactly the position of our bridges including the requested specifications. Truly admirable. We thus had a perfect picture of what the temporary bridges had to meet."