An atapper (from atap, the Indonesian word for "roof" also called a roofer or roof surfer) is someone who rides on top of a train, particularly in Indonesia. In Indonesia the government sees them as a nuisance and embarrassment, however, residents claim that they have no choice because they cannot be late for work, and public transit efforts are beyond woefully inadequate. Most of the people who ride on top tend to be risk-seeking young males, as it is dangerous.
Indonesia, especially Greater Jakarta has a huge problem with atappers, or urban dwellers who ride on top of trains, as gridlock grips this metropolis of 30 million without a single metro system, and the city comes up with unique coping mechanisms, such as car jockeys. Jakarta traffic is the most gridlocked in Southeast Asia, perhaps among the worst worldwide, it has built bus rapid transit, but with little success, as there is no separation from traffic and every inch of roadway is usurped by motorists, usually motorbikes but also private cars, as they flout traffic rules, bus transit becomes stuck in gridlock. The intense tropical heat and urban heat island effect also makes the top the only place on the train with plenty of air circulation.
Nowadays, due to a rising number of fatalities from atapping on an Electrified rail and operation of KRL Jabotabek, atapping has been declining significantly. However, atappers can still be seen on cheap, crowded diesel trains.
Trains in India are also infamous for atappers, but in Indonesia they stay on top of the roofs rather than hanging off the sides.