07 :: Fresh air

Link Sonnstein to the Central Bus Station and Central Station and use advertising to promote train and bus travel.

Have a route that connects the following stops: (See list below).
- Sonnstein (min 4 stops)
- Central Bus Station
- Central Station

Route with a CNG bus and with the clean air ad:
Attach level 8 at all bus stops in Sonnstein: (Only stops flashing purple).

Reward: Sticker.