The on-going work to replace the two Interstate 270 bridges over the Mississippi River between Missouri and Illinois has officially reached the midway point with completion of the South span which is set to open on Sunday. The joint project between the Missouri and Illinois Departments of Transportation connect Interstate 270 between North STL County and Madison County in IL.  Construction started in late 2022 and should be completed in 2026.  The $496 million joint project between MO and IL will replace the existing bridges with two new structures that will eventually expand the highway to three lanes in each direction. This Sunday Eastbound traffic will be shifted to the new South span and in January Westbound traffic will be shifted to the new span using a temporary crossover just West of the Canal Bridge.  Both East and Westbound traffic will use the new bridge while the adjacent structure is built over the next 2 years. During that time, you can expect delays and officials say drivers should be prepared for slow traffic. But MoDot Director Ed Hassinger says the bridges are a critical connection to the STL metropolitan region and a key link in the national freight network. Steve Potter, KTRS News.