After a loss of track power, CTA riders can expect lengthy delays Tuesday evening on the Purple Line and Brown Line, the transit authority said.

According to an alert from the CTA, the Purple Line Express service has been temporarily stopped between Howard and the Loop due to a loss of track power near the Merchandise Mart. The Brown Line service has been stopped between Armitage and the Loop, the transit authority said.

Purple Line trains are operating only between Linden and Howard at this time, and Brown Line trains are only running between Kimball and Armitage.

The transit authority is encouraging riders to use the Red Line to avoid serious delays.

“We are working to restore service as quickly as possible,” the transit authority said in the alert.