Extremely efficient drainage for architectural bus bridge

Zwolle will soon have a real "landmark". Buses from the city center and the north of the city will be able to use the new bus bridge from the beginning of 2019 to transport travelers quickly and comfortably to and from the new bus station. The elegant and meandering appearance of the architectural bus bridge represents a feat of engineering. Thanks also to an extremely efficient drainage system.

Designed by BAM Infra and ipv Delft creative engineers, the new bus bridge is one of the most beautiful bridges currently being built, according to Mark Visschers of IDS. The bridge is 254 meters long, meanders over numerous railroad tracks and is supported by two abutments and just four slender intermediate piers. IDS was contacted early on by BAM Infra to help think about drainage. "Tristan Wolvekamp of BAM Infra was in fact familiar with our unique drainage product EnviroBridge from international projects in Ireland and Great Britain and assumed that this could possibly be of great significance in Zwolle as well."

Maintenance and aesthetics
The new bridge is being built under a UAV-gc contract that includes maintenance. "A traditional drainage system with the pipe system at the bottom of the bridge would, on the one hand, detract from the slender design and, on the other, have far-reaching consequences in terms of maintenance," Visschers explains. "Because the bridge swings over a number of railroad ties, it would mean that train traffic would have to be blocked during maintenance work. Every year. That was not an option. By equipping the drainage system on the bridge with EnviroBridge drainage units, this is not something to worry about. Because our product was included in the initial design at the tender stage, it made a substantial contribution to achieving the maximum EMVI score." 

The 254-meter-long bus bridge features EnviroBridge drainage units on both sides.

Strength class D400
The 254-meter-long bus bridge features EnviroBridge drainage units on both sides. A total of 1,016 units are included in the bridge. The monolithic composite drainage products consist of recycled plastic for 60% and calcium for 40%. Says Visschers, "The production of one such drainage unit uses the equivalent of 520 recycled plastic bottles. In other words, as many as 529,000 bottles were recycled for this project. The elements comply with EN1433, the European standard for line drainage, and have been certified by the Lloyd's Register. The EnviroBridge units used here in Zwolle meet strength class D400, have an RWS profile with a sloping edge and are incredibly strong. They can withstand up to 40 tons completely free-standing. This is necessary because buses are constantly driving over the bridge and thus possibly over our elements."

According to Visschers, IDS worked very closely with the client during the process. "For example, together we came up with an installation plan and the application method. The result is accordingly. The continuous line of drainage openings is well liked, also in terms of design."  The bridge is expected to open to bus traffic in early 2019. As many as 1,200 bus trips will take place daily over the bridge.