Within seconds on Saturday night, a controlled explosion turned a 724-meter viaduct in downtown Nanjing into rubble.

About 2,600 holes had been drilled in the viaduct's 57 supports, which tumbled like falling dominoes.

The demolition was carried out for the construction of a tunnel to alleviate traffic pressure, according to the Nanjing urban planning bureau.

To guarantee local residents' safety, nearly 2,500 people living near the viaduct were evacuated from their homes. Another 3,900 were asked not to go out during the explosion.

More than 1,100 police officers were sent to the scene, and traffic control was implemented two hours before the explosion.

"All the windows of the buildings near the viaduct were removed, and the pipelines were covered by thick plastic and bamboo mats," said Zhou Fang, a safety expert from the Jiangsu Academy of Safety Science and Technology.

To compensate local residents for any inconvenience, each person evacuated received 100 yuan ($16) from the local government.

"All the residential buildings, if damaged in the explosion, will also be repaired for free," said Zhang Yu, from the headquarters in charge of the viaduct explosion.

"But, how to guarantee the safety of underground pipelines, and how to alleviate the shock waves caused by the falling deck, are more difficult than the explosion itself," said Xia.

After being in operation for 16 years, a 724-meter viaduct was demolished in Nanjing, capital of East China's Jiangsu province, on Saturday night. Zhao Jie / for China Daily