During these hours, the signal controls will be unable to operate mechanically and trains will be flagged manually through the intersection by crews on the tracks.
Normal operation is expected to resume for all four elevated rail lines on Sunday night, November 15.
The new system will help to improve the reliability of service by regulating train movement, speed and intervals at the Lake and Wells junction where trains enter and exit the Loop. With the current signal and control system, trains may experience delays while waiting for signal clearance when crossing into or out of the Loop.
The new system will reduce signal clearance delays by replacing the current system, which is more than 30 years old, with new signals designed to improve service reliability by regulating train movement, speed and intervals more effectively. The newer equipment also will reduce the cost of maintenance as aging equipment requires maintenance more frequently.
The Loop Signal replacement project began in 2007 and is expected to conclude in late 2010. The project is being conducted in phases to help minimize the impact to customers. The majority of the work has taken place on weekends and in the early morning hours.