The bus is slow. You need to take bus No.7 or s7, get off at the bus station, and then take bus No.330 from the bus station to the railway station. Half an hour is not enough. If you take a taxi, you can tell the master that you are in a hurry to catch the train and let him take the South Ring Road. Go straight west on the South Ring Road to the intersection of the railway station, and then turn north for 5 minutes to get to the railway station. Soon, it will be 10 minutes.