Brock Triffitt was driving home with his mates when he got out of the car and was left stranded on a Tasmanian bridge. What happened next is every mother's nightmare

A heartbroken family has demanded answers after a 16-year-old died when he was left by his friends on a remote bridge and was fatally hit by a car as he lay in the road.

Brock Triffitt, 16, was with friends on the Tasman Highway near Orielton in Tasmania just after midnight on New Year's Day when they stopped and released him.

His friends were driving a blue Mazda, which then took off, leaving him alone on the highway for an unknown amount of time before lying down on the asphalt.

Shortly afterwards, another car drove by, fatally hitting Brock as he lay there, killing him instantly and leaving his mother and six siblings devastated.

Ms Douglas said Brock's six siblings were still asking where their brother had gone

As grieving family members struggle to come to terms with what happened on Monday, family friend Kaylee Oakes has now launched a campaign GoFundMe to pay for his funeral.

Sharon Douglas, Brock's mother, said she doesn't blame the driver who hit her son for what happened since the road is notoriously dark and it was late at night.

“The (person) who hit him, I don't blame (them)… it's a long, dark road of a night. “I really feel sorry for them because that would be traumatizing to see,” she says told The Mercury

“I don't know what really happened, and I probably never will.”

Ms Douglas said Brock's six siblings were still asking where their brother had gone and when they would be able to see him again.

She last saw Brock when she dropped him off near Kingston to go fishing with friends, a hobby he had picked up from him grandmother, Robyn, and his father, Corey, who taught him the basics.

Mrs. Douglas praised Corey for “getting him in line” and that she was proud of the way her son was maturing.

She said he had shaken off the “mama's boy” label and planned to work with his father after completing year 10 at Montrose Bay High School.

His mother said her “gentle” boy loved woodwork and had recently built his grandmother a coffee table.

Police are still investigating the circumstances leading to the tragic accident and have interviewed everyone who was in the Mazda that dropped him off.

No one knows exactly what hit Brock, but police are investigating and his mother admitted the area (pictured) has terrible visibility at night.

Ms. Oakes wrote in the description of Brock's GoFundMe campaign that he was “like a little brother” to her and that proceeds would help his family who are “still in shock.”

“He was only 16 years old and his life was taken far too soon in an unexpected tragic accident,” Ms Oakes wrote.

“He was a kind, funny, intelligent, unique soul who was so generous to his friends and family.”

So far, the fundraiser has raised more than $4,500 toward the $10,000 goal, which will go toward his funeral, which has no date set.

Brock's family plan for installing one plaque near where he died on the highway.