Gateway Green Light

Gateway Green Light is a cooperative effort to improve the coordination of traffic signals throughout St. Charles County. The program helps synchronize traffic signals on streets throughout the county, especially those that cross city limits. This reduces unnecessary delays, improves traffic flow and cuts emissions that contribute to ozone pollution.

To report traffic signal concerns, contact Gateway Green Light at or call 636-949-1895.

How It Works

The state and local governments that own traffic signals in the area are working together to make sure that the timing plans for the intersections on major routes are coordinated for more efficient flow of traffic.

Although existing equipment is used wherever possible, some new communications equipment and software, and new signal controllers were installed so the traffic signals on the system can communicate with each other and with a central operations center. This equipment and software help keep the traffic signals in sync with new timing plans. To date, a total of 233 miles of fiber optic cable links observation cameras and 354 road signals to the system.

The program seeks to provide motorists with real-time information on roadway conditions and travel times through the use of dynamic message boards and travel time detectors. As Gateway Green Light infrastructure continues to expand, benefits to the public will continue to increase. For more information on existing and future technologies see Smart Infrastructure.

Helping Traffic Flow

Depending on factors like the length of a trip and the number of traffic lights, Gateway Green Light could save seconds or even minutes for someone driving on a coordinated route. Since thousands of vehicles travel along each road on a weekday, this could add up to noticeable improved traffic flow, especially during rush-hour periods in the morning and afternoon.

Participating Government Organizations

The following government organizations are working together to deliver Gateway Green Light: 

  • City of Cottleville
  • City of Dardenne Prairie
  • City of Lake Saint Louis
  • City of O'Fallon
  • City of St. Charles
  • City of St. Peters
  • City of Weldon Spring
  • City of Wentzville
  • Missouri Department of Transportation
  • St. Charles County

The Gateway Green Light Board, made up of representatives from each organization above, as well as East West Gateway, meets quarterly to discuss significant congestion locations, system status, managed incidents (crashes), and management of planned events (festivals, parades, planned roadway closures, etc.).


Quarter 1 GGL Board Report (PDF)
Quarter 2 GGL Board Report (PDF)


Quarter 1 GGL Board Report (PDF)
Quarter 2 GGL Board Report (PDF)
Quarter 3 GGL Board Report (PDF)
Quarter 4 GGL Board Report (PDF)

Thank you to the East-West Gateway Council of Governments for sharing this Outstanding Local Government Achievement Award Video on Gateway Green Light.