The arterial rail system of GLMZ, running elevated tracks through every district above Tier 2. The CL-9 cars are sixty years old and it shows — rattling frames, flickering displays, seats worn to bare metal. But it runs. Twenty hours a day, every eleven minutes, packed to capacity and beyond. For most of the city, the L is the only way to get anywhere that walking can't reach. The smell is a signature blend of ozone, sweat, and cheap synth-coffee.