Largest annual human migration on earth

In China, they're headed home. By the hundreds of millions, all in anticipation of the lunar new year which begins on January 23.
It's the largest annual human migration on the planet.
Trains, buses and planes have been packed and authorities have implemented an online ticketing system to accomodate the unprecedented 3.1 billion passengers traveling over the next few weeks.
So far, the new online system isn't receiveing rave review.
SOUNDBITE: Yang, 24-year-olf University student saying (Mandarin):
"If you keep on trying to log in, you get through after about 20 minutes, and after that when you click to purchase the tickets, it comes up with a "server busy" notification. Every time you reach this stage, you have to log in again, which takes more than another 20 minutes."
The holiday is the most important for the Chinese --- and for many, espeically migrant workers in the city, it is their only chance to travel home and seee family.
Deborah Gembara, Reuters