Apparently it is also the most secure method of travelling in this violence-wracked nation:
Passengers are searched before boarding the train and the railway company's guards in blue uniforms patrol the carriages.
"When the train goes by, people feel safe and feel that things are going back to how they were," said Colonel Ali al-Tamimi, the railway company's head of security.
And apparently gives the people a semblance of a modern, non-sectarian society - something they have been ironically missing since the invasion by US forces and the subsequent rise of sectarian violence:
"The railways are for all of us ... Do you think passengers declare their sect when they get on the train?"Women jiggled children on their knees and men chatted as the gleaming carriages pulled away from a spotless Baghdad platform, a picture of cleanliness and order in a country racked by chaos.
"Truth be told, we never really stopped the service," said Hashem. "Even when the situation was at its most dangerous, we kept going. It's our job."