Romain Grosjean's miraculous escape from the flames of his burning Haas car was testament to Formula One's impressive safety record.

Here, the PA news agency looks at some of the key elements which kept the 34-year-old Frenchman alive.

Did the halo save Grosjean's life?

Grosjean had been sceptical about the introduction of the halo, but following his escape he said: "I wasn't for it some years ago but I think it's the greatest thing that we brought to Formula One and without it I wouldn't be able to speak to you today."

The three-pronged titanium device sits above the driver's head and can withstand the weight of a double-decker bus. It is designed to prevent a driver from sustaining serious head injuries and was pushed through by the FIA following the death of Jules Bianchi.

The Frenchman succumbed to devastating brain injuries nine months after he crashed into a tractor at a rain-hit Japanese Grand Prix in 2014. Speaking after Grosjean's terrifying ordeal, F1 managing director Ross Brawn said: "There is absolutely no doubt the halo was the factor that saved the day, and saved Romain."

How did he survive for almost half-a-minute in the blazing inferno?

F1 doctor Ian Roberts described the harrowing ordeal facing Grosjean following his 140mph crash.

Englishman Roberts, the first man to arrive on the scene, said: "We saw the fireball early on, but then we could see there was half the car pointing in the wrong direction and then I thought where on earth is the rest? We looked to the right, saw a big gap in the barrier, and we could see Romain was trying to get out. It looked like an oven. It was red with flame."

Yet, somehow, the French driver emerged with only minor burns. While the halo has been credited for protecting Grosjean's head, new race suits introduced this year also played a significant role. While the overalls are heavier, they can protect the driver from a fire for up to 20 seconds, double the time of last year's suits.

It is also mandatory for the driver to be able to remove himself from the cockpit within 10 seconds, which includes taking their seat belts off and removing the steering wheel. They are subjected to strict FIA tests on this every year.

How did Grosjean penetrate a steel barrier?

The French driver's car split in two and burst into flames after he pierced through a steel barrier at 137mph following a collision with AlphaTauri's Daniil Kvyat.

The sudden impact with the exposed barrier at Turn 3 – which registered at an extraordinary 53G – meant there was almost no time for Grosjean to decelerate. And it is believed that the pure force of the crash and the angle at which Grosjean hit the barrier is why it split.

The halo and survival cell played their roles so Grosjean was not totally exposed. But speaking after the race, four-time world champion Sebastian Vettel said: "The guard rail is not supposed to fail like that."

What will happen next?

The FIA has launched an investigation into the accident, with question marks over why Grosjean's car broke in two, and how it caught alight. FIA race director Michael Masi warned that the findings could take several months.

"I would hate to speculate on why the car burst into flames," said Australian Masi. "We will perform a complete investigation from start to finish. It will take weeks, if not months, to look at every single aspect of what happened."