UPDATE: Pfeiffer Canyon Bridge on Highway 1 closed to traffic until further notice.

A couple of fractures in one of the two support columns for the Pfeiffer Canyon Bridge prompted Caltrans to close the bridge on Highway 1 to all traffic as of 5pm Sunday, according to a spokesperson.

Only pedestrians and emergency vehicles are allowed to cross the bridge until further notice. However, an incoming storm on Thursday could shut the bridge even to pedestrians for the duration of the rain, officials announced this afternoon.

Caltrans will not know until later this week the extent of the damage to the bridge caused by the shifting hillside, says Susana Cruz, acting manager of the Caltrans public information office in San Luis Obispo. 

The fractures were caused by the rain-soaked hillside shifting beneath the bridge, which is located near Sycamore Canyon Road. Specialized equipment is needed to measure the size and depth of the slide and will not be available to geotechnical crews for at least couple of days, Cruz says.

There currently is no timeline for when the bridge will re-open to vehicles.

"We don't have a short term or long term plan until we can get a full assessment," Cruz says. 

Earlier on Sunday, Caltrans was escorting vehicles one at a time across the bridge headed north.

Residents and visitors who needed to travel north after the closure were encouraged to park their cars at the Pine Ridge Trails parking lot, then walk back across the bridge.

Highway 1 continues to be closed between Ragged Point in San Luis Obispo County and Pfeiffer Canyon Bridge, due to multiple mudslides that occurred since rainstorms began hitting the coast in late January.

The highway is impassable between Ragged Point and Dolan Point, according to a Caltrans statement issued at 1:55pm on Sunday. 

Caltrans officials recommended that if any residents or visitors wanted out of the section between the two points, their only option was to move their cars north of the bridge, and “be escorted by businesses to and from destinations south of the bridge.”

Businesses remain open, the statement said.

The water-logged hillsides will get to dry out a little between today and Wednesday, before rain is expected to return. The National Weather Service is predicting a 90-percent chance of rain on Thursday, with more rain on the way throughout the weekend.

In an announcement made at 3:50pm, Caltrans warned residents the storm could mean closing the bridge completely for its duration.

"It is unknown how the bridge will sustain itself or whether pedestrian traffic will still be available. The bridge may need to be completely closed for the duration of the storm; safety precautions/preparations are advised."

Editor's note: This post was updated to reflect the latest information from Caltrans as of 1:45pm and 3:50pm Monday.