GDOT's $51M Widening of SR 92 Makes Progress

Caltrans Plans to Reopen Highway 1 by Mid-September

Wed June 06, 2018 - West Edition #12
Chuck Harvey


Repairs at the site of the Mud Creek Slide have cost about $54 million so far.
(YouTube image)
Repairs at the site of the Mud Creek Slide have cost about $54 million so far. (YouTube image)
Repairs at the site of the Mud Creek Slide have cost about $54 million so far.
(YouTube image) Caltrans hopes to secure some federal funding for the cost to stabilize the mudslide area and prepare a surface over the top of the slide that can be used for a short stretch of roadway.
(Jim Shivers/Caltrans photo) Caltrans plans a mid-September reopening of a stretch of Highway 1 near Big Sur that has been blocked nearly a year by a huge landslide.
(Jim Shivers/Caltrans photo) The size of the slide has made planning and repairs difficult.
(Jim Shivers/Caltrans photo) Despite the late rains this season, progress was made in the effort to repair the Mud Creek slide area.
(Jim Shivers/Caltrans photo) Just the plan to build a road over the top of a huge slide is a new approach that required a lot of thought and ingenuity before a plan could move forward.
(Jim Shivers/Caltrans photo)

Caltrans plans a mid-September reopening of a stretch of Highway 1 near Big Sur that has been blocked nearly a year by a huge landslide following strong winter storms in 2017.

So far, the repairs have cost about $54 million. Caltrans hopes to secure some federal funding for the cost to stabilize the mudslide area and prepare a surface over the top of the slide that can be used for a short stretch of roadway.

The central California coast experienced a dryer winter in 2017-2018 than it did the season before. But heavy rains hit the area in January and again in early spring this year.

On Jan. 9, 2018, an astounding 9.6 in. of rain fell on Mining Ridge on the Big Sur coast, and Highway 1, which had still not recovered from the previous winter's damaging rains. The area suffered new blockages.

Highway 1 was closed from 4.6 mi. north of Ragged Point. The closure was needed to allow for mudslide removal, according to Caltrans, which advised motorists to use alternate routes.

Despite the late rains this season, progress was made in the effort to repair the Mud Creek slide area. But the size of the slide has made planning and repairs difficult.

Just the plan to build a road over the top of a huge slide is a new approach that required a lot of thought and ingenuity before a plan could move forward.

Securing New Section

Crews have used existing rocks in buttressing the roadway, to secure what will be a new section of roadway.

Rocks also have been brought in from Piedras Blancas to the south and Monterey County to the north to further stabilize the roadway.

Highway 1 Vital to Area

Reopening Highway 1 is vital to the popular coastal area. The strength of the local economy depends on it.

But work must be done in a safe, well-planned and well-organized way.

The slide cut visitation and hurt businesses on the major tourism route that includes classic California coastal vistas and landmarks between Los Angeles and San Francisco.

The California Department of Transportation's estimate for reopening the highway is subject to change, however, The Tribune of San Luis Obispo reported recently.

“Caltrans will continuously evaluate the opening date as work progresses,” Susana Cruz, Caltrans District 5 public information officer, said in an email to the Associated Press.

Another update will be issued in July, and even after the reopening, lane closures and road work could continue, Cruz said.

The remainder of Highway 1 is open to traffic from San Luis Obispo north to Monterey.

“That can change come wintertime,” Cruz told Construction Equipment Guide.

Cruz said the repair using existing materials at Mud Creek is considered a long-term fix.

“But it will take a couple of winters to settle into the long-term solution … the slopes need to settle, if that makes any sense,” she said.

Contractor for the Mud Creek project to reopen Highway 1 is John Madonna construction of San Luis Obispo.

Equipment at the construction site includes excavators, spiders, hauling and delivery trucks. In summer, the contractor will bring in bulldozers, asphalt laying equipment, rollers and crews that specialize in the late stages of highway construction.

The roadway repair is about a quarter mile in length. The highway has one lane in each direction at the construction site.

About 50 workers are on duty each day at the Mud Creek site.

2017 Monster Mud Creek Slide

Highway 1 has been damaged and closed by slides over the years, but the one that hit at Mud Creek near Ragged Point in May 2017 was monumental by comparison. Millions of tons of earth moved, displacing a total of 75 acres of land.

The vast amount of material in the slide buried the highway that runs along costal slopes above the Pacific coast. It was determined that 6 million tons of rock and dirt fell onto the highway at Mud Creek.

The debris slid well out into the ocean, creating 15 acres of new coastline about 9 mi. north of the Monterey-San Luis Obispo county line.

Caltrans has since been working to stabilize the slide debris, so crews can rebuild the highway over it. The work included building a massive rock seawall at the foot of the slide.

Highway 1 has been closed in various places from Ragged Point to Big Sur since December 2016.

Since then, Caltrans has been working to build a roadway over the top of the slide that buried the old road under tons of dirt.

The question of when the road will reopen through the area has been a complicated one, with weather conditions, geologic hazards and stability questions of primary consideration.

New Stabilizing Features in Place

Cruz said new stabilizing features including rock curtains, rock-fill buttresses, embankments, berms, rocks and netting are going to be put in place.

“This strategy is allowing Caltrans to rebuild the road more quickly and at a lower cost than other alternatives such as structures, a tunnel or major earthwork that puts additional fill into the ocean,” she said.

To make sure the new road is stabilized, it will include new safety features such as embankments, berms, rocks and netting, Cruz said.

Caltrans tried letting traffic through during the rains, but as the slide activity increased, it became too dangerous to continue letting the public and locals through at the location.

Crews have continued to smooth the crossing that traverses the mudslide. Bulldozing and cuts at the north and south have helped improve the road bed at Mud Creek.

Although crews have made progress in improving the crossing, they are not yet ready to start laying down asphalt.

“It's too preliminary at this point,” Cruz said.

Mud Creek — South of Another Damaging Slide

The Mud Creek work is being done about 25 mi. south of where another segment of the highway was blocked when a storm-spawned landslide wrecked a bridge in early 2017. Last October, Caltrans completed the $24 million Pfeiffer Canyon Bridge replacement at the site, allowing the roadway to reopen at the location.

The new bridge was designed without support columns because columns could be vulnerable in future slides.

CEG