Song Youzhou, a Chinese inventor, may yet have the last laugh. Faced by gridlock in cities, he drew scepticism six years ago when he proposed a futuristic “straddling bus” that would rise above traffic jams. “Driving through it would feel like crawling under someone’s crotch,” one critic wrote online.

Vehicles under 2m high can pass beneath the bus, which was derided by critics but which could soon become a reality

In July Mr Song’s unusual design may finally have its first test run along a special track in the coastal town of Beidaihe, where China’s Communist party leaders gather for summer holidays and secret talks.

Marketed as “a great original invention of China” that can benefit the entire world, the TEB (Transit Elevated Bus), or “straddling bus”, appeared at an exhibition in Beijing. Visitors crowded around a model that showed the TEB passing over two lanes of traffic.

Up to 1,400 passengers will be able to board the upper layer at platforms to be built in the middle of the road, at 1km intervals. The platforms will also function as pedestrian bridges.

At a speed of up to 37mph, the electric bus will run on steel tramlines. There is no lower level, allowing vehicles under two metres high to pass beneath when the bus is at a stop or to be overtaken, when traffic is heavy.

The bus will function like an underground system yet require only a fifth of a subway’s construction costs, and be completed in a year, says Song.