At least 2.5 million Muslims began the annual hajj pilgrimage today, heading to an encampment near the holy city of Mecca to retrace the route said to have been taken by the prophet Muhammad 14 centuries ago.
Travelling on foot, by public transport and in private cars, the pilgrims will stream through a mountain pass to a valley at Mina, two miles outside Mecca.
The hajj, one of the world's biggest displays of mass religious devotion, lasts for five days. In the past it has been marred by fires, hotel collapses, police clashes with protesters and deadly stampedes.
Islam is followed by a quarter of the world's population and the hajj is a duty for all able-bodied Muslims who can afford it once in their lifetime. Many wait for years to get a visa. "I can't explain the feeling of being here," said Mahboob Bangosh, a Canadian pilgrim from Toronto of Afghan origin.
To minimise the risk of overcrowding and to lessen congestion on the roads the authorities will for the first time be operating a Chinese-built train that will call at hajj sites. The £1.1bn project has 12 miles of track and will transport 180,000 passengers, said Habib Zein al-Abideen, the assistant minister for municipal and rural affairs.
"We will have a capacity of 72,000 passengers per hour next year. This year we operate at 35% capacity. Next year we could have 500,000 to 600,000 passengers," Abideen said. Due to its limited capacity, the train will this year only carry residents of Saudi Arabia or other Gulf Arabs and next year will open to other nationalities.
Saudi Arabia has worked hard to improve facilities to ease the flow of pilgrims at hajj. In 2006, 362 people were crushed to death.