For a visit to Tianjin I took the currently fastest train which takes 1 hour and 15 minutes. For the Olympics there will be the really fast train in operation which will take only 30 minutes for this route. At train stations in China you cannot just walk in and go to the platform. You need to wait in the waiting hall or at the entrance to the platform and only get admitted about 15 minutes before take-off and only with a valid ticket. It was quite crowded in Beijing so I do understand that it probably is safer this way.
I took my trick bike and met the crew from Tianjin TV who filmed me riding my trick bike in Tianjin for their program Right Here.