German authorities have blasted a nearly 500-metre long bridge to the ground in a spectacular display that used 120 kilograms of explosives.

The 70-metre-high old autobahn bridge near Wilnsdorf, in the western German state of North Rhine-Westphalia, was brought down on Sunday (local time).

Government infrastructure operator Autobahn GmbH said it was the first time an autobahn bridge of that height had been demolished.

The 55-year-old structure near the Hessian state border collapsed as planned with the help of explosives placed in 1850 boreholes. It was watched by a crowd of hundreds.

The bridge’s 16 piers and road surface fell to the ground in a massive cloud of dust. Crucially, its swish new replacement nearby, which has been in use since last December, was left untouched.

The work is part of an expansion of the autobahn’s Sauerland line, one of the largest road construction projects in that part of Germany.

There are 60 bridges along the route that will be renewed. Fifteen new bridges are already under construction or planned to begin this year.

-with agencies