Berlin: Traffic on the Rhine halted; trams and cars could not cross a main highway bridge, and about 20,000 Cologne residents on either side of the river were forced to leave their homes and gather, for safety's sake, in the gyms of schools closed for the day.
Seven decades after the end of World War II, the threat of aerial bombs still disrupts life in Germany with surprising regularity.
A bomb found along the riverbank during excavations for a heat pipeline forced the mass evacuation of everyone within about a half-mile radius. That included people in homes, businesses, a nursing home, a 45-story apartment building and a youth hostel.
In the end, it took half an hour to defuse the 440-pound bomb, believed to have been dropped by the Americans in the waning years of the war.
Mass evacuations are no aberration in Germany. The Cologne evacuation was the largest the city had seen since the war's end, but it was one of more than a half-dozen instances in Germany in May alone in which large devices were discovered, several of which required evacuations.
This month, about 1,400 residents in Erkrath, near Dusseldorf, in the industrial state of North Rhine-Westphalia, were forced to retreat to safety while a 550-pound bomb was being defused.
In Hannover, more than 30,000 people were temporarily uprooted to ensure that no one was injured after a bomb under a onetime schoolyard was found.
Other bombs were found in Ingolstadt, in the German south, and Kiel in the north, some of which caused smaller-scale evacuations.
Last year, the official bomb squad attached to the Interior Ministry of North Rhine-Westphalia, the most populous state in Germany, defused 918 World War II-era bombs there alone and disposed of other ordnance, including grenades and land mines.
The discoveries show the enormous firepower unleashed on Germany in World War II and indicates the haste with which the devastated country sought to recover.
"It is an issue in most major German cities, where anywhere from 5,000 to 10,000 unexploded bombs are believed to be lying under the ground," said Sebastian Dosdall, head of GFKB-MV, a private company that specializes in clearing old munitions. "It is a problem that will not be solved easily. It will be with us for quite a while yet."
The Allies carpeted industrial or urban areas, among them Cologne and Berlin, with thousands of tons of bombs during the final years of the war. Rather than safely dispose of them at the time, the Germans simply buried them in the rush to rebuild adequate housing after 1945.
Now, with many of the 1960s- and '70s-era buildings being torn down to make way for new buildings, the rusted and corroded devices are turning up.
Experts warn that these devices are as dangerous now as they were during the war, prompting the regularity of wide-scale evacuations.
Bomb squads regularly analyze aerial photographs taken by the Allies to try to pinpoint the unexploded ordnance, but many bombs remain difficult to detect. Experts said they had combed the site where the Cologne bomb was found.
Some of the dormant explosives were products of the Germans themselves, part of the enormous war machine that kept munitions factories busy in the prelude to World War II and during the fighting. In the later stages of the war, those munitions were gathered in central storage areas, and many were later dumped into rivers or other waterways.
Construction of wind farms off Germany's Baltic and North Sea coasts has been slowed by the thousands of devices dumped there by pilots during the war. Private companies have expanded their areas of specialization to include underwater clearance, Dosdall said.
Wolfgang Wolf, 62, of the Cologne municipal team responsible for clearing war ordnance, said if the riverbank bomb had gone off, the blast could have shattered windows and ripped off roofs.
Before defusing the bomb, he told the Kolner Stadt-Anzeiger newspaper that such an action is as simple as turning a screw. "But if something goes wrong, it would have far-reaching consequences for the whole region," he said.
Johanna Klaes, 86, was among several older Germans who said the evacuation on Wednesday was a strange reminder of the war years. She recalled Allied bombing raids and evacuations to the nearby countryside.
This time, though, she was able to return to her home after only a few hours.
© 2015, The New York Times News Service