Maggia river: new rock ramp passes scale-model test at Cevio

A 1:40 scale model has shown that the new rock ramp planned for the Maggia river withstands an exceptional flood. The test was carried out in the Laboratorium 3D facility in Iragna and reproduced the stretch of river near Cevio, where a flood killed eight people in 2024.

The simulation recreated what is known as a hundred-year flood, which occurs on average once a century: a water volume of 1,200 cubic metres per second, greater than last year's flood. The goal was to check whether the new structure can protect the Visletto cycling and pedestrian bridge, which was built on the foundations of an old railway bridge dating from the early twentieth century.

"La rampa si è comportata molto bene, e ha garantito la stabilità di questa opera di premunizione" ("The ramp performed very well, and ensured the stability of this protective structure"), Christian Tognacca, co-owner of Laboratorium 3D, told the RSI programme Quotidiano. Without the intervention, he added, erosion would have been much more severe and could also have endangered the bridge's piers.

The ramp is made up of thousands of stone blocks that will each weigh four tonnes in reality. According to Laurent Filippini, head of Ticino's water courses office, it is essential to stabilise the bridge's foundations, since they rely on a weaker construction technique than today's: the piers of the new road bridge, by contrast, were driven deeper.

More room for the river, and for nature too

The measures are not only about safety. Upstream of the bridge, wider channels were created to direct the water. According to Tognacca, this has also had positive effects on the environment: sandbanks, incisions in the riverbed and greater habitat diversity in the floodplain.

To reach this result, the Canton of Ticino spent around 300,000 francs on tests that lasted nine months. Public spending that the canton now considers justified, given the model's results. From January, the actual full-scale work can begin along the river.

The intervention comes just over a year after the flood that devastated the region in 2024, and is part of a broader programme to make the territory safer following that tragedy. It remains to be seen how much the final construction of the ramp will cost and on what timeline, and whether similar measures will be extended to other flood-prone stretches of the Maggia, to protect the communities living along the river.

Meanwhile, on Saturday the new Visletto road bridge will be inaugurated in Cevio.