Taxi from Pudong airport to Hongqiao rail station

About how much is the meter fare from Pudong airport to hongqiao high speed train after midnight.

My friends will arrive at 23:30. After immigration and collection of luggage, it will be over midnight. As they have to take the early speed train to YiXing, they will go to Hongqiao to wait till next morning train. As they cannot spead Chinese, I am helping them to get info first. Do they need to book train in advance or upon arrival at the rail station.