City authorities are developing an ambitious plan for a new transport network that could include boats or ferries as well as amphibious buses, Green party transport spokesman Lino Hammer told The Local.

“There's high pressure on transport in Cologne,” Hammer said. “As well as building roads and cycle paths, we need a whole new mode of transport.”

Floating buses are already a feature of life in the Hamburg harbour, where they are a tourist attraction, as well as in other large European cities including London and Rotterdam.

But Cologne politicians think they can be put to more practical use to overcome the limited capacity on the city's bridges, which turn into bottlenecks at rush hour.

By shifting traffic away from the land, planners hope to solve the jams and make new-build houses along the banks of the Rhine more liveable.

It's hoped that it will be a quicker and easier way to relieve the pressure than building a new bridge – a huge construction project the city currently can't afford.

“We already have seven bridges. They're a big effort and very expensive,” Hammer said.

“There are plans for one in the south of the city, but it could be 25 or 30 years before it's built.”

Rather than just waiting, Hammer hopes to get the first water buses running by 2020 to relieve pressure on the city centre.

Now the city hopes to launch a pilot scheme with water transport between the Porz and Rodenkirchen neighbourhoods – although whether it will use amphibious buses or more normal river craft has yet to be decided.

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