Subway riders on numbered lines and the L train will have to figure out when their train is arriving the old-fashioned way on Saturday — by turning their neck and trying to see if it’s coming.

Countdown clocks won’t be working from 6 a.m. to 6 p.m. while the MTA does maintenance and testing work, a spokeswoman said. The Subway Time app will also be down during the same period. 

Nine subway lines will also be disrupted by MTA construction work as well.

Some of the changes include the No. 6 running express downtown between 125th Street and Grand Central station from 11:45 p.m. Friday to 5 a.m. on Monday.

There will also be no G train service in Brooklyn between the Church Av and Hoyt-Schermerhorn Stations. Riders are asked to use the F train instead.

The late-night N service between late Friday and early Saturday morning will also run on the Q line between Canal Street and Dekalb Avenue, and won’t hit local stops like City Hall and Jay Street-MetroTech.

The R also won’t run in lower Manhattan and parts of downtown Brooklyn on Saturday. Between 6 a.m. and 8 p.m., it will be rerouted on the Q route between Dekalb Avenue and Canal Street.