Long bus driving

A new commuter bus going into service in China bills itself as the largest in the world. It seats a some 300 passengers.
It also purports to be accessible, though the description sounds like to me it might be somewhat problematic. Says the Shanghai Daily: "It is easy for elderly and the disabled to enter as the first step is nearly level with the pavement. The bus also has room for wheelchairs."
So how close to level with the ground do you suppose nearly is?