The separately filed Santa Monica Superior Court lawsuits contend that all of the entities share liability for the allegedly dangerous roadway design on that portion of PCH and for not implementing live-saving safety measures.
"For far too long, Pacific Coast Highway in Malibu has been and continues to be unsafe for pedestrians and drivers alike," the plaintiffs' attorneys said in a joint statement. "As a result of the defendants' complacency, far too many lives have been needlessly lost."
The goal of the lawsuits is to force the government entities to "do what they should have done a long time ago so no more lives are needlessly taken," according to the joint plaintiffs' attorneys' statement.
A Caltrans representative did not immediately reply to a request for comment.
Officials announce new campaign to promote safety on PCH in Malibu
Pepperdine seniors Niamh Rolston, Peyton Stewart, Asha Weir and Deslyn Williams were walking to an event on Oct. 17 when they were struck and killed on the northbound shoulder of a section of PCH known as "Dead Man's Curve," a short stretch between Las Flores Canyon and Carbon Canyon Roads.
The stretch of PCH has seen the highest number of auto accidents on the overall 21-mile coastal road, according to the plaintiffs' lawyers.
The four Alpha Phi sorority sisters were killed when a driver lost control of his vehicle on the curving road and traveled into the northbound shoulder, where he first collided with a legally parked car, then continued northbound and struck the four women as well as a fifth student, who was injured, but survived.
No safeguards were in place for pedestrians even though the defendants have known about the dangers for decades, the suits allege.
A sheriff's captain reported that from 2013-23 there were 53 deaths and 92 serious injuries in the area and attempts to improve conditions through law enforcement have had minimal or temporary results, according to the suits.
Actor Rob Lowe, a Malibu resident, tweeted his feelings after a June 2015 crash that killed rapper MC Supreme, calling the singer's death "sad and unacceptable," the suit states.
Correction: The date of the fatal crash was misreported in the earlier version of this article.