Romain G꧒rosjean fears there could be "carnage" on standing restarts that could be used in Formula 1 following a red flag stoppage in 2018 following initial trials in Barcelona this week.

In a revised sporting regulation for the 2018 season, F1 race director Charlie Whiting will be able to call for a standing restart following a red flag period in a race if conditions are deemed suitable, with the cars returning to t🅷he track behind the safety car after the stoppage.

"Once the safety car has entered the pit lane all cars, with the exception of those that we✤re in their garage at the time the race was suspended, must return to the grid, take up their grid position♎s and follow the procedures set out in Article 36.9 to 36.13," the FIA regulation reads, with the cited articles relating to the usual start procedure after a formation lap.

A trial of the new🍰 system was attempted at the end of both the first and second days of the second pre-season test in Barcelona on Wednesday, with Grosjean raising concerns about the procedure as the drivers would have cold tyres and be unable to pull away.

"I didn't go above fourth gear," Grosjean ꧃said. "It's undriveable. I was one of the first guys to come on the grid so I sat there with [Valtteri] ♐Bottas for a long time.

"But when we꧑ restarted, it was like it was raining on slicks. Every time you upshift, the rears spin and wheelspin. Every time you downshift, the rears lock. You go into a corner and slide. It's doesn't work.

"Safety-wise, I'm a bit concerned because as I say, I went to fourth gear and that was the maximum I could d🐻o.

"To me it could be carnage. You can lose the car in a straight line, and if someone loses it and then people are behiꦓnd...

"We tried it, and honestly I was not having much fun just trying t♔o upshift and downshift, it was tricky. Bottas was in front of🎃 me, and he was not having much fun either.

"I don't know what pace we've done, but look at the sector.🔯 It's going to b✤e very, very slow."

While conditions in Barcelona throughout testing have been 🐬cold, Grosjean felt it did not have any relation 🐷to his difficulty at the standing start come the end of the day.

"It's pret𒐪ty cold, but we know that if you spin and then you♛ restart and you try to push again, the tyre's normally gone and you never put the temperature back in," Grosjean said.

"So imagine doing a slow lap and then aborting and then another one. We were down in 40 degrees or something like𒅌 that with tyres. They just don't work.

"At Monaco you need 20 laps, and I'm not even sure you're going to get the temperature back. Some tracks it's fine where you manage to g🦋enerate temperature - [but in] Canada, here with those conditions, China, not sure you're going to get temps again."