BIG SUR — The southern entrance to Big Sur will not re-open until late next summer — nearly a year and a half after fierce winter rains triggered a massive Mud Creek slide that covered iconic Highway 1.

Caltrans announced Friday that it aims to have Highway 1 at Mud Creek open to traffic by late summer 2018. The new roadway — which will traverse over the slide area, using a series of embankments, berms, rocks, netting, culverts and other stabilizing material — will cost an estimated $40 million. Related Articles Dolan Fire near Big Sur grows, injured firefighters improve, winds move smoke north

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That means persistent hard times for Big Sur businesses that rely on tourism from Lucia, Santa Barbara, Los Angeles and other Southern California cities.

It also means cancellation of anyone’s plans next summer to make the classic coastal Highway 1 drive between Northern California and Southern California.

The breathtaking coastal retreat will remain a cul-de-sac, accessible only from the north and east. The posh Post Ranch Inn flies in guests by helicopter from Monterey Regional Airport for multi-night stays ranging from $4,300 to $13,500.

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Highway 1 has posed challenges ever since its asphalt was first poured along a ledge in Big Sur’s steep sandstone and shale cliffs in the 1920s and 1930s. More than 60 times in its history, the route has been buried by landslides.

Even before last winter’s rains, about $130 million was budgeted over the next decade for Highway 1’s repair, replacement and realignment.

But the Mud Creek slide on May 20 was stunning in its scope. The landslide sent more than 5 million cubic yards of rock and dirt onto the roadway and into the ocean, making it the largest-ever slide along the Big Sur coast.

“The landslide at Mud Creek is one of the largest in California’s history. We are working to safely rebuild the road in this complex and unpredictable area,” Caltrans District 5 Director Tim Gubbins said in a statement.

There is good news: Soon there will be access to Big Sur from the north, via a new Pfeiffer Canyon Bridge.

Work on that 900-ton bridge — costing $24 million — is expected to be completed later this month. Earlier this week, the bridge made its final descent onto its abutments.

With the massive Mud Creek slide in the south and the downed Pfeiffer Canyon Bridge to the north, the only access to Big Sur has been by the long and perilous Nacimiento-Fergusson Road over the Santa Lucia mountain range.

The precise timeline for rebuilding over the Mud Creek slide is dependent on this winter’s weather conditions, Caltrans officials say.

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Caltrans and the U.S. Geological Survey have watched and worried over five distinct slides on the steep 1,100-foot mountain. Their fears were realized when an entire flank collapsed almost near the crest of the Santa Lucia Mountains.

The landslide created a new apronlike point into the Pacific Ocean, expanding the California coast by a stunning 13 acres — the size of 10 football fields.

Caltrans’ geotechnical and engineering personnel studied the radar assessments and other data to find the correct path to replacing the section of Highway 1 at the slide site.

The area was still restless two months ago. In July, Caltrans called the slide “ongoing and still active.”

“The whole environment is very unstable, with steep rock right on the coast and really complex geology,” said Gary Griggs, a professor of Earth and planetary sciences at UC Santa Cruz. “It is just a messy area.”

“What they’re doing,” he said, “is what they’re going to have to continue doing.”