Modular auxiliary bridge TK58 is true spectacle

Some twelve Retro Bridge modular bridges have rendered their service on and around the A16 Rotterdam over the past few years. Most of them were dismantled between the middle of last year and the beginning of this year. However, a number of elements have recently been deployed again to enable the final piece of the operation, the replacement of the viaduct in the A16 over the Hoofdweg (KW58). A true spectacle for Retro Bridge, as the temporary bridge (TK58) is exceptionally large in terms of surface area and must guarantee the flow of traffic at one of the busiest traffic junctions in our country.

Through an earlier agreement with construction consortium The Green Arch, Retro Bridge supplied the necessary auxiliary bridges to create the Rottemer Tunnel and the connecting road route, among other things. "This involved a wide variety of auxiliary bridges for a mix of functions. For example, we delivered bridges used only by (heavy) construction traffic, as well as bridges for through motorized traffic and bicycle and pedestrian bridges," says Han Kastermans of Retro Bridge. "With the exception of one pedestrian bridge, all of those temporary bridges were dismantled between the summer break of 2023 and January 2024. Outside of this contract, De Groene Boog approached us a year ago to provide the temporary bridge structure TK58 to replace KW58. Along with the request to realize that with the released Retro Heavy Bridge elements that were already in the project."

102 by 25 meters

Engineering structure KW58 was identified several years ago as a high-risk viaduct. As a precaution, the structure was provided with a support structure so that it could continue to perform its function safely. The extensive replacement operation has now begun. To make this possible, traffic in both directions is diverted over a temporary bridge construction. Traffic from north to south has been diverted over Retro Bridge's TK58 since April 29. "Our auxiliary bridge is located in the A16 at the Prins Alexander exit," Han explained. "The deck is a total of 102 meters long and 25 meters wide, which is exceptional by Dutch standards. That's because the four lanes are projected onto the deck in a radius of arc." 

1,500 tons

Retro Bridge's TK58 is composed of 120 elements and good for a total weight of 1,500 tons. "The bridge consists of three partial spans of twice 40.5 meters and once 21 meters all from our Retro Heavy Bridge range," Han explains. "It was calculated in detail and the elements were carefully selected. In the lanes are the most recent elements, while the somewhat 'older' sections are included in the strands on top of which are the guardrail and barriers. So logistically, it was quite a puzzle to select the right elements from all the released elements in the project. In the end, the elements were brought to the pre-construction site - on the other side of the highway - in mid-January and we assembled the three sections here."

Tight deadline

TK58 rests on removable supports that De Groene Boog installed itself. "In early March, we assembled the first partial span of 40.5 meters by 25 meters. To do this, the deck was moved into position with extensions and laid on the supports with large cranes," Han outlines the course of events during assembly. "A few weeks later we were able to assemble the other two parts in the same way, so that The Green Arch was able to commission the temporary artwork (TK58) neatly before the deadline on April 29," says Han. Retro Bridge's TK58 is scheduled to remain in service for 76 weeks. "Then the new viaduct will be ready, we will dismantle our bridge and will no doubt be able to use the elements elsewhere."