Subway passengers are required to buy a ticket for the correct fare. Many transit systems operate on an honor system basis, with enforcement officials inspecting tickets periodically and issuing fines to those who board without paying.
Passengers are not allowed to smoke in subway boarding areas or on subway cars. Passengers cannot subject other passengers to the inhalation of poisonous chemicals or other cancer-causing agents.
Any music must be played through personal headphones and remain inaudible to fellow passengers. Playing loud music through portable boom boxes is prohibited. Passengers generally may use laptops and cell phones on board the subway car. Even video taping and photography are permitted while on some subway systems.
