More than 200 cars were included in the incidents Jan. 12 that killed two people.
Investigations of the accident are in full swing, although it will be a few weeks before they will be completed, police officials said.
Initial reports pointed to heavy fog as a contributor to the driving difficulties.
"It's progressing at a rate we'd expect," said Sgt. Larry Harrison of the Ingham County Sheriff's Department. "Such a large-scale accident takes a considerable amount of time and effort."
The sheriff's department and Michigan State Police Lansing Post number 11 are working together to complete the investigations.
Michigan State Police Lt. Pat Richard said the information gathering has been going smoothly.
"All of the troopers and officers from agencies have done an outstanding job," he said.
Each department is investigating one of the fatal accidents, as well as numerous other accidents.
They are waiting for toxicology results and are completing interviews, Richard said. The cases will then be sent on to the Ingham County Prosecutor's Office.
The fatal accidents being investigated involve two area residents.
Douglas James Baker, 15, from Holt, died after the car he was in was rear-ended by a tractor-trailer.
His grandmother and mother were taken to Lansing's Sparrow Hospital, and his grandmother was released over the weekend.
His mother, Cathy Baker, 40, remains in the hospital in fair condition, said Nan Simons, Sparrow Hospital spokeswoman. The upgrade occurred this afternoon, and Baker was moved to a rehabilitation unit.
Jason Eldridge, 27, of Owosso, was killed instantly when the passenger truck he was driving hit a different tractor-trailer in the rear.
Some of the drivers who survived crashes are remembering the scare.
Shannon Arana, who is six months pregnant, and husband Roberto Arana were on their way home from Lansing when they were hit from the rear on I-96.
Shannon, 26, was driving, but was able to stop the car before hitting a semi on the road in front of them. Then, the rental car she was driving was hit twice.
"We saw we were going to get pushed under the semi in front of us," she said.
Her husband moved to switch seats with her, but as they were trading, they were hit again and her head cracked the windshield, completely shattering it, she said.
They were able to switch, and Roberto Arana was able to get the car off the road.
Shannon was taken to the emergency room, "a scene out of the TV show E.R.," she said. She remained there overnight.
After she was released, she had to locate the vehicle and get her personal things out before it was towed.
Shannon said it took a few days for the experience to sink in.
Shannon, a 2001 MSU graduate, had been laid off the day before from her pharmaceutical sales job and was looking for a new car in Lansing the day of the accident.
"That's a lot of things to have happen in 24 hours when you're six months pregnant," she said.
The Aranas also have three children, all under the age of 3, who were at home at the time of the accident.
"I am so grateful they weren't with us that day," she said.