Devil’s Slide will be open in late September, says Caltrans

Breaking news

Posted by on Mon, May 15, 2006

Caltrans will sink 160 ties 150 feet into the slide to anchor to a much larger slide below. Click for larger version.

Highway 1 at Devil’s Slide will be repaired in four months, toward the end of September, according to Caltrans.

At a press conference in Redwood City, Caltrans announced their plan for the repairs and their estimate for completion. Describing this year’s slide as more extensive than the one in 1995, Caltrans District 4 Director Bijan Sartipi said that over 100 horizontal tiebacks would be sunk under the roadbed twice as deep (150 feet) as those used last time, plus another 60 tiebacks will be sunk 100 feet into the cliff face above the road, in order to anchor the slide to a much larger slide below it.

The repair is "not permanent", Sartipi cautioned, but is designed to last until the tunnel is operational in 2011. "We hope Mother Nature will cooperate until we can finish the tunnel," he said.

In order to complete the repair this quickly, contractors have committed to working around the clock.  Installing the horizontal ties below the roadbed will require drilling crews to be suspended in cages over the cliff from cranes.

That would put the total duration of the closure at around 180 days (April through September)—significantly longer than the 103-day consensus estimate in the contest sponsored by Coastsider:

“Caltrans District 4 Director Bijan Sartipi said that over 160 horizontal ties would be sunk twice as deep (150 feet) as those used last time in order to anchor the slide to a much larger slide below it.”

I’m a little confused by the above statement by Bijan of caltrans. From looking at the diagram it looks like the slide is being anchored to more stable land to the east not below.
In any case it’s like securing two sinking ships together. It does make sense as a temporary fix using a slower sinking ship to slow the sinking of a fast sinking ship.
Perhaps some knowledgeable member of the group could explain the fix in more detail.

We’ll have more detail on how the repair will work later today.

This seems like much more work and a much more permanent fix than the last time the road went out.  I guess we should all look at the bright side and thank Mr. Sartipi for all of the dillengent work he has done.  The pictures this site has of the 1983 slide show how bad it could have been.  HMMMMM.  How long WAS the road close in ‘83,....  85 days!!!!!!  I remember the Chronicle ran several stories on the slide then.  I guess we are lucky we have Mr. Sartipi running things now instead of 1983 otherwise we would STILL be waiting for a fix.

I just spoke to the consumer affairs person for the devil’s slide project, John Cunliffe.  He said there is a window to try undo what has been done and seek a more temporary solution in a faster time.  He proudly stated to me that the repairs they are undertaking will shore this up for 15 yrs to come!!!  That’s the problem we only need 4 yrs.
None I repeat NONE of the old repairs have been looked at as options, according to John.  CALTRANS is insisting on a bigger fix than they undertook in 1995. 

WE NEED TO STOP THEM.  He said if we all spoke against their proposal at the meeting tomorrow night at the adcock center we may be able to get them to reconsider. 

The problem is none of these people at CALTRANS were anywhere near the BAy Area in 1983 when the slide really went out and was fixed in 84 days!!!!  We need the 83 or 1980 fix.  All we need is 4 yrs.

robert stegner wrote:
“I just spoke to the consumer affairs person for the devil’s slide project, John Cunliffe.  He said there is a window to try undo what has been done and seek a more temporary solution in a faster time.” 

Something tells me that the potential liability to CalTrans of settling for a “quickfix”—that might result in somebody’s car falling into the ocean before the tunnel is completed—is going to stop that from happening.

Are you crazy or is it the voices in my head telling me that????
This whole slide thing is a conspiracy by caltrans to repair the road so that it can be used as two lanes of a freeway from pacifica. The tunnel is the other two. The makers of nose rings and tattoo ink plan to have montara renamed South Pacifica. Dynamite the slide and save us from the evil!!!!

Hmmmm. Looks like someone doesn’t know the twin tunnels already are sized for four lanes..

As for the outage in the early 80’s, Caltrans dragged its heels then, as well. The section of roadway that went out when a wedge of the larger landslide slipped after three weeks of solid rain (not at the end of a long rainy season as some would suggest for all the slide outages that occur every ten to 15 years in especially wet periods) was actually repaired in a matter of weeks when they decided to do it. The repair was not unlike what was done in the 90’s and is planned for this year, with rods run into the hillside to help anchor the roadbed. The section that slipped in the 80’s was more on the nose of the curve just south of the portion that slipped in the 90’s and again now. The slippage at roadbed level was not as long in the 80’s as in the 90’s. The biggest repairs for the outage in the early 80’s were at Martini Creek and at Green Valley; in both locations highway fills with creeks running through culverts at their bases were completely washed away. All of which makes the overly long time it took to reopen the road in the 80’s look even faster in comparison to the even more recalcitrant, bureaucratic, insensitive Caltrans behavior in the two episodes to follow.

But back to that underground freeway: won’t all of you now be just that more compliant when the cost runs up to, possibly, a half billion before it is open?

Carl May


The 83 ‘temp’ fix was the best they have ever done, it lasted over 12 yrs longer than the 95 fix and we only need 4 yrs.  why are they attempting to do a permenant fix now????Let buklldoze it like it has been done for the last 70 yrs. everytime t went out and open in a couple of weeks.

CalTrans has $7.5M in emergency funds to spend on playing with the slide at our road closure expense.  Based on surface imagery, it’s hard to understand CalTran’s claim that the sliding is worse than 1995.  The bulk movement of the slide
from the April 2006 images appeared to be under 5 feet. Caltrans drilled two bore holes on the north and south end of the slide in April.  CalTrans reported detecting movement at about 80 feet in one of the bore holes last month.  Last week, CalTrans said the movement has slowed to what it is in the dry season.  Now, they propose an extensive anchoring system that may take 10 percent of the remaining lifetime of the roadway to implement.

CalTrans has held this close to their vest and sealed the site off with a security perimeter.  The first question to ask, before a fix or even a band aid is proposed, is why did the slide roadway fail in April?  Well, there was a long period with much heavier than normal rainfall.  According
to Keyhan Moghbel of CalTrans the two well pumps on the slide were operating, when the slide failed.  At the April 12 MCC Meeting, citizens asked Keyhan Moghbel about CalTrans lack of
maintenance of the drains and ditches on the slide prior to the failure. At the MCC meeting he said he would look into it and get back.  At the Pacifica City Council meeting last week, I
asked him about the maintenance of the drains and his commitment to get backs on that.  He did not answer the question.

The effects of rain on the slide have been controversial. Dr. Hovland proposed dewatering the slide.  This was rejected by CalTrans.  One can read some of the controversy in the Tunnel EIR volumes I and II on CalTrans’ website.  There is also a good general discussion of the slide geology there.

The issue I have is there are 40,000 to 100,000 cubic yards of loose sedimentary rock and dirt on a 45 degree slope over a sloping relatively impervious granodiorite base.  Rain or an earthquake is going to produce sliding action.  CalTrans is proposing to hold back roughly 40,000 cubic yards of loose sedimentary debris material
with something like 100 to 200 tiebacks anchoring not to granodiorite bed rock, but to loose sedimentary material that’s only anchoring quality is what other loose sedimentary debris is loosely sitting on top of it.  The 1995 tiebacks were supposedly about 65 feet horizontal into the slide.  We civilians don’t know how the 1995 tiebacks failed: tension rod snapped, anchor pulled out, slide material flowed around them or the whole system just slid down as part of a bigger slide(I’d guess the latter).  The proposed
anchors will hold a dry pile of rocks, while the contractors work on it.  But, will it survive the added weight of being saturated with water again or an earthquake?  Nothing has in the past century.

I’m not a geotechnical expert.  I just studied these reports so, I could attempt to figure out what CalTrans was up to.  But, even the experts can’t agree except presumably those within
CalTrans.  There has been a century of failure on the slide.  If an independent geotechnical expert was to look into it now, how long would that investigation take, would the CalTrans Engineers have to take time away from their ongoing design to answer pesky questions form outsiders and based on the response to previous work by Dr. Hovland would CalTrans even listen?  The best one could hope from an independent geotechnical investigation would be that the design is overkill or a waste and a recommendation to limit the number of tiebacks and boring.

As an alternative to CalTrans proposed four month plus anchoring project, I would propose a more modest approach. The 1995 repairs worked.  After ten years of acceptable movement, the roadway began to subside during a period of exceptional rainfall in April.  CalTrans sensors detected the movement and the warning signs were turned on.  CalTrans came out surveyed the damage and slowed the traffic down and eventually shut the highway down. By CalTrans own statements their 1995 objectives were met in April.  Presumably, the 1995 anchors were pulled down the slide a few
feet, some bore holes and drains severed and cracks on the surface.  Now, the slide has dried out, slide movement has slowed to acceptable
levels.  At this point, I would suggest refilling the sunken roadway, repave, clean out the drains and ditches and reinstrument the slide. This whole process could take as little as a month.  Should there be a subsequent failure, the regimine of closure, scaling, drilling sensor bore holes, repaving and reinstrumenting can be repeated as needed for the next five years.

The decision on repairs SHOULD HAVE traded off the current repair cost, cost of roadway down time and the risk and additional cost of a one per ten year subsequent failure.

Vince Williams or someone else absolutely needs to show up with Vince’s excellent comments and questions at the Caltrans presentation at the HMB City Council tonight. Are there plans to do so? I am going to attempt to make it - but I’m not sure I’ll be able to.

No one wants to compromise safety - but I think Vince raises critical questions. If Caltrans claims that their design is the only safe design in any timeframe, then so be it. But I think they should have to justify why a shorter repair cannot be done.

If it is true that a much faster repair can be done that will last with reasonable periodic patching until the tunnel opens, then our communities should demand *LOUDLY* that be done instead.

Brian Dantes
El Granada

Ahem, the ‘83 repair to the highway on the slide did not last a mere 12 years. So far it has lasted 23 years, and we’re still counting. The ‘83 outage was not in the same place—didn’t even overlap—as the ‘95/present roadbed movement.

Carl May

I don’t think 2 full lanes with an emergency lane could fit into each tunnel. It makes much more sense to put the old highway to use as the other two lanes. 


Re: size of the tunnels—
No, three lanes won’t fit in each planned tunnel, but two plus a shoulder will. There is no capacity need for a second lane, let alone a third, in each tunnel—except to boost the size and cost of the project. In fact, there is no need for two tunnels as far as expected capacity goes. These tunnels are the size of those built on four-lane Interstates, not on two-lane coastal highways that are, by law, supposed to remain two-lane in scenic rural areas.

If the current highway is to be put to use, there is no need for even one tunnel. There was no need for a 5- to 6-lane roadbed (plus shoulders and dividers) cut through Montara Mountain, so why would there be a need for six lanes of roadbed—four underground and two outside—at the slide?

It’s all District 4 of Caltrans being District 4 of Caltrans. The only significant difference this road closure is that without the bypass opponents pointing out Caltrans spin, lies, and pecadillos, almost everyone is rolling over for the nonsense.

Carl May

I have heard that there is not adequate ventilation planned for the size of the tunnels. This comment came to be via a environmental engineer that has no stake in the coastside whatsoever… Any comments?

As for planning for a road which will last 15 years, hurray for CalTrans… planning for something that long might mean that CalTrans can make it last the duration of the tunnel construction which is certainly like to be longer than any of us can imagine at this point.