Major Route Z Closure Starts Today; Expect Significant Delays on I-55 and I-70

Morning Traffic Overview for Monday, March 9, 2026

Commuters across the St. Louis metropolitan area should prepare for a complex Monday morning drive as several new and ongoing construction projects hit critical phases. With the start of the work week, the Missouri Department of Transportation (MoDOT) has officially launched a major closure in St. Charles County, while long-term bridge and pavement projects continue to restrict flow on major interstates like I-55 and I-270. Additionally, today marks the beginning of Severe Weather Awareness Week in Missouri, and local authorities are reminding drivers to ensure they have multiple ways to receive emergency weather alerts while on the road.

New Construction: Route Z and I-70 Impacts

Starting today, Monday, March 9, MoDOT has closed Route Z under Interstate 70 in Wentzville. This closure is part of the extensive "Improve I-70" project stretching from Warrenton to Wentzville. Drivers who typically use this underpass for local access will need to follow posted detours, as this route will remain inaccessible for bridge and interchange redesign work. Traffic on I-70 itself may experience periodic slowing near the interchange as crews move equipment into place for this new phase of construction.

Ongoing Major Interstate Constraints

Commuters heading toward the city center or traveling through south St. Louis should account for the following heavy-impact zones:

• I-55 Southbound: One southbound lane remains closed from I-44 to north of Bates, with two lanes restricted from north of Bates to north of Weber. These closures for bridge rehabilitation are expected to last through early 2026.
• I-55 Ramps: The Virginia Avenue on-ramp to southbound I-55, as well as the southbound exit and entrance ramps at Loughborough, remain closed.
• I-270 / Route 370: Lane shifts are in effect near the Discovery Bridge over the Missouri River. While two lanes are open in each direction around the clock, the median barrier work continues to create congestion during peak morning hours.
• Telegraph Road (Route 231): Safety and sidewalk improvement projects are active between the city limits and Franru Lane, resulting in intermittent lane reductions.

Public Transit and Metro Alerts

Metro Transit reports that all services are currently operating on normal schedules; however, riders should be aware that the agency is currently testing a new fare system. Updated ticket vending machines are being installed at select MetroLink stations, and passengers may encounter technicians testing gate validators throughout the day. Commuters should also prepare for an upcoming quarterly service change scheduled for next Monday, March 16, which will affect schedules for 26 MetroBus routes.

Safety Reminder: Severe Weather Awareness

As today is the first day of Severe Weather Awareness Week, the focus is on "Receiving Weather Information." Drivers are encouraged to check their vehicle's emergency kits and ensure their mobile devices are set to receive Wireless Emergency Alerts (WEA). In the event of spring storms, MoDOT reminds all motorists to never drive through flooded roadways and to reduce speeds in all active work zones.