ST. LOUIS - The first new span of the new Chain of Rocks Bridge has been completed, marking the midway point of the bridge's construction.

Authorities with both IDOT and MODOT are calling the opening of the first span of the new bridge over the Mississippi River a significant milestone. Monday will be the first weekday commute when drivers will use the new span. A second stretch of the new bridge is yet to be built.

FOX 2's Nissan Rogue Runner drove the new span. Eastbound Interstate 270 traffic shifted to the new south span using two lanes Sunday. Weather permitting, westbound I-270 traffic will shift to the new span next month, using a temporary crossover just west of the canal bridge. Westbound traffic will also have two lanes across the new bridge.

While the adjacent structure, the second span of the new bridge, is under construction over the next two years, eastbound and westbound traffic will use the new bridge.

On Friday, Bommarito Automotive Group SkyFox was on the bridge, overseeing the completion of the new bridge stretch. The $496.2 million joint project between IDOT and MODOT will replace the existing two spans of the Chain of Rocks Bridge with two new structures.

The new spans will have wider shoulders to accommodate the eventual expansion of I-270 to three lanes in each direction. There is also a companion $35.4 million MODOT project to reconstruct the Riverview Drive interchange. The new bridge's construction began in 2022, with completion scheduled for 2026.