BERLIN — Explosives experts today successfully defused an unexploded American bomb from World War II in the western German city of Cologne, authorities said.

The 1,100-pound bomb was found Monday evening during construction near the Rhine River in the center of the city. A TV station and the opera house had to be evacuated during the defusing operation. Shipping on the river and air traffic overhead were also interrupted before the defusing operation got underway.

Officials closed down a bridge across the Rhine that takes most trains to Cologne’s main train station, one of Germany’s major rail hubs. The suspension of traffic in Cologne led to delays in train services across all of Germany.

Almost 75 years after the end of the war, unexploded bombs are frequently found in Germany. Disposing of them sometimes entails large-scale evacuations as a precaution.