Police in Hong Kong have increased security measures ahead of another clampdown planned on road and rail links by anti-government protesters.
Only passengers are being allowed into the airport building or to use the Airport Express, boarding in downtown Hong Kong.
The train is not stopping en route on the Kowloon peninsula.
The protest is the latest in 14 weeks of demonstrations in the city.
The measures are aimed at avoiding the chaos of last weekend, when protesters blocked airport approach roads.
Protesters also occupied the arrival hall last month, halting and delaying flights.

Death toll from Venezuela quakes rises to 3,535 as thousands remain displaced
Russian strikes kill 26, exposing Ukraine air-defence shortages
Clashes escalate at Sri Lanka prison to leave 25 dead, many more injured
Six killed in India's Mumbai as rains wreak havoc, disrupt travel
Wildfire in southern France forces 10,000 people from their homes