The investigation into the car crash that killed four teens in Woodacre is expected take several more weeks, the California Highway Patrol said Friday.

Meanwhile, residents continue to visit the crash site and roadside memorial, a debate is emerging about what might be done to make the redwood-lined stretch of San Geronimo Valley Drive safer.

An online petition posted at bit.ly/4iADHwb to close the road to motorized traffic “until further notice” had nearly 80 signatures by Friday. But several dozen people posting on a San Geronimo Valley social platform were overwhelmingly critical, saying the road is needed for emergency response. It is one of two roads into Woodacre.

The petition author, Ted Waiser, could not be reached for comment.

Visitors who stopped by the memorial site and in Woodacre on Friday uniformly agreed the road should remain open, but also said there could be safety enhancements such as cautionary signs, a lower speed limit and a greater law enforcement presence.

“I don’t know if this road should be closed or not, but I definitely think there should be speed checks and railings,” said Linda Vela of Fairfax, who left a crucifix by a charred redwood. “There needs to be more than just nothing here.”“They should widen the road and take the speed limit down,” said Robert Vela, her nephew.

The Marin County Department of Public Works has put up caution signs warning to watch for stopped vehicles before the memorial and red stanchions at the crash site, where there are dozens of bouquets, photographs, notes, candles and other offerings.

“We’ve taken some immediate steps this week,” said Julian Kaelon, a public works spokesperson. “And we’re continuing to evaluate safety enhancements.”

The agency will assess what additional steps are appropriate after the CHP finishes the investigation, he said. “Our focus is on understanding the current conditions and behaviors along this corridor, so we can identify potential safety improvements.”

The girls, all students at Archie Williams High School, were traveling on the road on April 18 when the vehicle they were riding in struck a tree, according to authorities. Olive Koren, who was in ninth grade, and 10th-graders Sienna Katz, Ada Kepley and Josalynn Osborn were killed, according to the Tamalpais Union High School District. Marley Barclay and the driver, Elsa Laremont Stranczek, survived the crash.

San Geronimo Valley Drive was laid out as a horse-and-wagon path in 1865 and was widened and first paved in 1929, said Dewey Livingston, a historian and expert on West Marin’s roads. It was the main road into the San Geronimo Valley until Sir Francis Drake Boulevard was built in 1955.

Today, San Geronimo Valley Drive is the first left-hand turn when coming down the hill from Fairfax. It is a two-lane road with wide shoulders that quickly narrows as it enters a redwood and fern forest. Traveling west, the road has a 40 mph speed limit and some curves where a driver’s view of oncoming traffic is blocked.

There are no homes along the three-quarter-mile stretch between Sir Francis Drake Boulevard and where the drive enters the edge of Woodacre, where its residential streets begin and a handful of businesses are located.

“It officially opened as Sir Francis Drake Highway in 1929 and it hasn’t really changed,” Livingston said. “It was well engineered at that time. … Marin is one of those rare counties where 100-year-old roads have not been improved to modern standards.”