New bridge sections are moved slowly into position at Beijing's Sanyuanqiao junction on the 3rd Ring Road on Sunday. Replacement of the decaying bridge took only about 36 hours. Workers used global positioning systems, lasers and robots to replace old sections with prefabricated steel structures. Traffic flow resumed late on Sunday afternoon. [Photo/China Daily]

Workers on Sunday morning finished reinforcing an old pivotal cloverleaf junction in a downtown Beijing commercial zone using a new prefabricated steel structure.

The most challenging part of the overhaul, the replacement of the 1,300-tonne bridge structure, began at 11 pm Friday at the junction on the northeastern Third Ring Road.

Replacement of the bridge structure cost 39 million yuan ($6.1 million  dollars), according to Xinhua.

The Sanyuanqiao cloverleaf junction is a major congestion point on a tollway to the airport. It also links two pivotal highways: the Third Ring Road and the highway linking downtown Beijing with the outlying Shunyi District.

Built in 1984, the bridge was in poor shape and needed reinforcement for safety reasons.