Metro riders on the Red line can expect more delays.

Metro has identified communications cable along a segment of the Red Line that is in need of replacement. The cable is 40 years old and dates back to the original construction of the rail system.

Starting Thursday, Metro will slightly modify Red Line service which will increase delays until new cables are installed.

The cable is used by the signal system to transmit train speed and location data between control rooms located at Brookland, Fort Totten and Takoma.

“We have detected a condition that, left unaddressed, could affect the integrity of the signal system, and that is something we take very seriously,” said Joseph Leader, Metro’s Chief Operating Officer. “Safety demands that the cable be taken out of service and replaced.”

Metro will be limiting the number of Red Line trains between certain stations. Only one train at a time is permitted on each track between Brookland and Fort Totten and one train on each track between Fort Totten and Takoma.

Metro is planning to replace trains with buses along a section of the line this weekend to install new cable.

Previously announced Red Line weekend single tracking between Farragut North and Judiciary Square has been cancelled.

Instead, free shuttle buses will replace trains all weekend between Silver Spring and Rhode Island Avenue stations. Customers can use the Green Line between Fort Totten and Gallery Place as an alternate route.

During rush hours, trains between Shady Grove and Glenmont will run every 10 minutes, rather than every 8 minutes. Additional trains will run between Grosvenor and NoMa-Gallaudet, resulting in service about every 5 minutes between those stations, rather than every 4 minutes.

If the cable installation this weekend goes as planned, normal Red Line service may be restored as soon as Monday, December 18.