I think there would be 5 basic requirements, besides possibly having to pass an ideological exam, that they must have before being accepted to traffic school: they must have 20/20 vision, be relatively tall, attractive, not overweight, and be resistant to spin vertigo. Anything else could be taught in training.
As for schooling, in addition to the requsite studies of both the Great Leader's teachings and the Dear Leader's inspirational quotes, they probably are issued a lenghty Traffic Girl manual for studying, after which they must first pass written tests dealing with mundane things like traffic circle dimensions, baton length, hand signals, right of ways, uniform dress code regulations, Government vehicle identification, etc.
Then they must be taught and drilled for precision marching, baton exchange, pirouette technique including snapping of the feet back together, proper arm angles and baton wielding, whistle usage, etc.
I can imagine that there is an outside training ground at the school compound complete with streets and intersections in differing configurations such as a one lane street intersecting with a one lane, a one lane with a two, a two lane with a two, T intersections, Y intersections, etc.
While using the training ground they would practice dealing with various traffic scenarios, with the students alternating training in the traffic circle with being the "traffic" and driving the cars. There are probably many common standard traffic situations they would be drilled on, and as time goes by the more proficient the trainee becomes, the more complex the traffic situation she is presented with.
Finally, after several months and when all their training is finished, there would be a graduation ceremony held in front of a bleacher filled with family and friends - probably at the training ground - where they would be presented with the official Traffic Girl diploma complete with fancy lettering and government seals all over it.
Lastly, they would then be issued their own tailor-made Traffic Policewoman uniform, which would come with a small leather clad box containing the shiny new Kim Il-Sung pin which they will proudly wear just above the left front pocket.
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