The SkyTrains are automated and driverless. In theory, they are the perfect fit for a 24/7 service transit system. But, some parts of its infrastructure are 40 years old and require daily maintenance, most of which is done at night.

The Vancouver SkyTrain does not operate 24 hours a day primarily due to its single-track maintenance requirements. Unlike systems in New York or Chicago that have third or fourth "express" tracks, the SkyTrain mostly consists of two tracks (one in each direction). Because the system is automated and highly reliant on precisely maintained sensors, tracks, and power lines, engineers require a daily "maintenance window" (typically between 1:30 AM and 5:00 AM) to perform inspections, grinding, and repairs without live trains. If the system ran 24/7, any major track work would require full daytime shutdowns, which would be far more disruptive to the city's 500,000+ daily riders. To bridge this gap, TransLink operates a network of NightBus routes that follow similar paths to the SkyTrain lines during the early morning hours.