The accident occurred between Enköping and Bålsta at lunchtime on Saturday. It wasn't until midnight that traffic flowed again in both directions.
On E4 north of Uppsala, around ten vehicles collided on Saturday morning.
Despite the extent, Bengt Olsson is overall satisfied with the effort from the Swedish Transport Administration's side.
We solved it as well as we could. There were very many vehicles, and some were not drivable, so we had to take it step by step and repair some railings, he says.
The pileup is now being investigated by both the police and the Swedish Transport Administration.
We at the Swedish Transport Administration are looking at the road, i.e., the construction, and if there were any damages or anything else that could have affected, says Bengt Olsson.
Had Salted the Road
According to Olsson, the road had been salted shortly before the accident. Despite this, several motorists testify that it was very slippery and that vehicles skidded uncontrollably into the traffic jam ahead.
The slipperiness may have had several causes, such as the road salt ceasing to function at minus eight degrees, which usually makes the surface more uneven, says Olsson.
But then you have a number of cars that polish the road surface. And then new snow comes, regardless of whether you've been with a snowplow just a moment ago. Then it doesn't take many minutes before the wind and snowfall have taken over again.
The Swedish Transport Administration believes that in recent years, they have seen increasingly intense weather changes that cause problems in traffic.
In recent years, we've seen these shifts in weather between plus and minus degrees. And then a snowfall comes that initially would have come 10-20 miles in another direction, but lands right there, says Olsson.
That's why I say it's more important today to keep track of local weather.
Several Injured
In total, around 120 people were taken to hospitals in Uppsala, Enköping, Västerås, and Stockholm after the accidents, several with serious injuries. Two people were admitted to intensive care. Their condition is reported to be stable.
By 9 pm, most had been able to leave the hospitals.
"Given the number of cars involved in the two accidents, nearly 100 vehicles in Grillby, it's pure luck that it didn't turn out worse than it did," says Mikael Köhler, healthcare director in Region Uppsala, in a press release.
