Why there is no lighting in the tunnels in the subway

Why there is no lighting in the tunnels in the subway

Surprisingly, in the first decades of operation, the subway tunnels were lit around the clock.

The press service said that the subway has two main types of lighting - working and emergency. Emergency include only when necessary, and working lighting is intended for night scheduled work on the stage.

The lighting in the tunnel can be seen if you travel on the first five trains in the morning, and then turn off the light. Engineers light their way with spotlights on trains, as well as low beam from the head train. 

Source: https://peterburg2.ru/news/pochemu-v-metro-net-osveshheniya-v-tonnelyah-49583.html