The Airport Express could cut the number of trains running in off-peak periods because of under-use. Scores of carriages are carrying few or no people, with the number of passengers per day about 9,000 less that initial estimates of 36,000. However, during peak periods, trains and platforms are packed. The variations have prompted the Mass Transit Railway Corporation (MTRC) to plan a study of passenger flow. Numerous trips by the South China Morning Post on the system have shown many of the 11 cabins per train to be empty most of the time. Although seats were full last night as travellers headed to the airport for weekends away. An MTRC spokeswoman said the review would help to identify peak periods and gauge passenger demand. Its results could see services cut during off-peak hours and increased during peak periods. '[Determining peak periods] will not be based solely on the survey but the study will contribute,' the spokeswoman said. 'There are other factors to look at also such as population growth and flight patterns. 'But the survey is being planned and we are just deciding on when to start.' She said the corporation might wait for passenger flow to stabilise before conducting the study. Democratic Party transport spokesman Albert Ho Chun-yan supported the study, saying he was surprised there were peaks and lows in demand. 'This is not a commuter railway, it is an airport railway and flight schedules are fairly evened out so I am surprised rail demand is not the same - it definitely requires study,' Mr Ho said. Several passengers riding the Airport Express yesterday had cabins to themselves, but said they were not surprised given the costly fare. Canadian Cath Fairbairn said: 'It is quite spacious already, but with so few people in the cabin I can hog two seats, use the laptop and stretch out a bit.'