Will Macron’s ‘bold’ Olympic opening ceremony be a bust? Just hours before it starts, Paris is hit by traffic chaos as rail lines are destroyed and weathermen predict downpours during the four-mile river parade

Paris has promised to make the opening ceremony of the Olympic Games the most spectacular ever seen, but traffic chaos, “malicious” vandalism and forecast showers threaten to disrupt the parade.

Emmanuel Macron’s “daring” plans see the River Seine used as the stage for a six-kilometre-long procession, with athletes passing by in boats in front of more than 300,000 spectators.

The show starts at 19:30 (18:30 BST), with meteorologists predicting a high chance of downpours in the French capital. Authorities are hoping the open-air party won’t turn into a bust.

As the ceremony is the first in history to be held outside a stadium, it will pose an unprecedented security challenge to ensure the safety of sports stars, dignitaries and the public, with French officials calling it the “largest peacekeeping operation ever.”

Police are on high alert due to the threat of a terrorist attack and after vandals carried out a series of coordinated arson attacks on railway infrastructure overnight. Organizers fear more sabotage will take place during the Games.

Just hours before the opening ceremony, fires broke out early this morning at key railway facilities, bringing train services to a standstill.

The “coordinated” attacks paralysed major stations as several services were cancelled, including those aimed at attracting sports fans to the French capital.

British travellers heading to the Games queued at the Eurostar terminal at St Pancras station in central London due to the disruption, which threatens to affect tonight’s show.

The procession of athletes is the first boat parade on the Seine since the wedding of Louis XV’s daughter three centuries ago. Photos of the preparations show how the parade is a nod to French culture and history.

Hundreds of thousands of people pay to stand on bridges and along the river, but it is unclear how the spectacle will be protected from possible bad weather.

The Meteorological Institute predicts a high chance of rain tonight in the French capital. The chance is greater than 50 percent when the ceremony starts, but by 11 p.m. it is almost 100 percent certain that there will be showers.

At the same time, controlling the crowds will be a major problem as people will want to get to the city centre as quickly as possible before it is closed off.

The Ring of Steel operation sees security measures spread across the city, rather than just at central locations as at the London 2012 Olympics.

About 45,000 police officers and gendarmes are being mobilised, including officers from Britain and other foreign forces, plus 10,000 soldiers.

Security forces spread out across the four kilometres of the ceremony, with precision shooters on rooftops and in helicopters circling above.

For the first time, France’s three elite units – the RAID, the GIGN and the BRI – will operate side by side, with a combined force of 650 men.

The air force is also being mobilized to secure the airspace and combat any drones flying over the ceremony.

Metal barriers have been installed along the Seine and around the streets and boulevards. Spectators’ bags will be checked and they will have to enter a special QR code when passing through the gates.

The British Foreign Office is warning tourists: ‘Until Friday 26 July, you will need a digital pass to travel to certain parts of Paris due to preparations for the Olympic Games Opening Ceremony.

‘Different rules apply depending on whether you are travelling on foot, by bicycle, by car or another vehicle.’

“It is the biggest security challenge that a country has ever had to organize in peacetime,” Interior Minister Gérald Darmanin told reporters on Tuesday.

During the ceremony, a flight ban the size of Belgium is imposed in northern France due to fears of a terrorist attack.

All three Paris airports will be closed from early evening until around midnight, causing major disruption to traffic on one of the busiest travel days of the summer.

The French Civil Aviation Authority said in a statement: “A temporary prohibited area is being created to ensure the implementation of special air security measures as part of the protection of the opening ceremony of the Paris 2024 Olympic Games.”

Olympic organisers have long feared sabotage attacks against the multi-billion dollar Games. A large-scale £350m security operation has been launched in Paris to counter the threats.

The largest peacetime deployment of troops in France’s history includes some 75,000 soldiers, police officers and private security guards.

“We are focused and ready,” said General Lionel Catar, one of the military planners before the spectacular opening.

The priority is to protect the approximately 80,000 participants as they sail down the Seine in dozens of boats, in front of some 350,000 spectators and a television audience of more than a billion people.

Gérald Darmanin of the French Interior Ministry said that “the terrorist threat remains high” and that “a high level of vigilance” remains essential.

France, which has a history of terrorist attacks, is on high alert for the Games, including during tonight’s opening ceremony.

In May, police arrested an 18-year-old suspected of planning a jihadist attack on the Saint-Etienne stadium, where the Olympic football matches are being held.

Last week, a neo-Nazi was arrested on suspicion of plotting an attack during the passage of the Olympic flame.

As part of their massive crackdown on crime in the run-up to the Games, French authorities have evicted hundreds of squatters from the city centre and jailed hundreds of people in an attempt to clear the streets.