The red-light camera program brought in about $21 million in fiscal 2017, according to a letter the PPA sent this year to PennDot. Almost half of that — $10,541,496 — was used to maintain the system and its operations. Net revenue from the cameras is supposed to go to transportation improvements statewide, with Philadelphia receiving half that money, city officials have said. The PPA has managed the red-light cameras for the city since 2006 and currently operates 134 cameras.