MOUNT ARAFAT, Saudi Arabia: With millions of people descending on Islam's holy cities in Saudi Arabia for the annual haj pilgrimage, transporting worshippers poses a huge challenge for the kingdom.
"We have reached nearly 2.5 million pilgrims this year and transporting all of these pilgrims is a challenge", Saudi Transport Minister Nabil al-Amoudi told AFP.
According to the minister, "7,400 planes full of pilgrims arrived this year via Jeddah and Medina airports" and "more than 18,000 buses were mobilised" for the haj.
The pilgrimage is one of the five pillars of Islam that all Muslims must undertake at least once in their lives if they have the means.
One of the largest gatherings in the world, the haj is a set of rites unchanged for 14 centuries that takes place over five days between the holy city of Mecca and the surrounding hills and valleys, in the west of the kingdom.
A metro connecting three stages of the haj will transport "360,000" pilgrims this year - a "record", according to the transport minister.
This line, opened in 2010, has the distinction of only operating five days a year.
Of the 2.49 million pilgrims participating in the haj this year (from Aug 9 to 14), the overwhelming majority will arrive by air and only a few thousand by land and sea routes.
A number of pilgrims also go to Medina, the other holy city of Islam in Saudi Arabia, though it is not a mandatory part of the haj.
At the end of September, a high-speed train line was opened linking Mecca and Medina in just 2.5 hours, halving the previous travel time.
This year, the train - dubbed the Haramain (the holy places) - will transport between "20,000 and 30,000" pilgrims, before gradually increasing its capacity in the coming years, Amoudi said.
For the sites around Mecca, transport during haj remains chaotic.
Thousands of buses spewing exhaust cause interminable traffic jams at all hours, meaning travelling a dozen kilometres (around 7 miles) can take half a day, if not longer.
The air is almost unbreathable, especially at the top of Mount Arafat, one of the stages of the haj, leading some pilgrims to don surgical masks.
It is another hurdle for Saudi Arabia that comes with hosting the haj, Amoudi said.
"Regarding the pollution created by the buses, we are considering methods of reducing these emissions," the minister said.