Trouble on the road

The CHP says Caltrans is evaluating this dip in the westbound lane of Highway 92 to make sure it doesn't become a sinkhole. It was not immediately clear what authorities were going to do about it or when it would be fixed. Photo courtesy CHP

UPDATED 4:35 p.m.: The westbound lane of Highway 92 remains closed after road crews discovered a "dip" that could grow into a sinkhole. Caltrans said one-way traffic control was in effect on the major artery to the coast in time for the evening commute.

The trouble is west of upper Highway 35. The road was initially closed in both directions this morning as Caltrans evaluated trouble. By early afternoon, the San Mateo County Sheriff's Office tweeted that the eastbound lane, separated by a k-rail divider, was open but to expect delays. 

There was no word on when the problem would be rectified. Caltrans has been at the scene since midmorning evaluating the dip, according to CHP Redwood City spokesman Art Montiel.

"It's believed that with the unstable ground underneath, if vehicles drive over it, it could become a sinkhole and that's why we've closed the road," Montiel said. 

Highway 92 has held up rather well since the second round of rain began on Jan. 4. There has been minor ponding on the road and in the shoulders. It did close for a time on New Year's Eve when flooding of the Pilarcitos Creek spilled over onto the roadway.

There has been another obvious area of concern since then that the state transportation agency had temporarily fortified with sandbags and a tarp. It is near the lower lake area, on the shoulder of the westbound lane. The pavement broke away sometime last week and washed down the hill and appeared in need of repair. The area has been marked with traffic cones for several days.

(9) comments

smor2000

Please, please to the powers that be...if 92 is closed indefinitely, can you please make the Coronado stoplight fix a priority? Traffic was backed up from El Granada to the southern outskirts of Half Moon Bay this morning. Like South of Kelly Ave. Please fix the light! Thank you!

Scott McVicker

Lets look a bit closer at that photo. In upper center of this lane you see the back of a diamond-shaped sign. To the left of that, a metal guardrail (mounted on wood posts embedded in the earth). This indicates a rise in the adjacent earth elevation. Then we see a transition to a concrete element, shaped somewhat like a K rail. In this stretch of the roadway, the adjacent earth level fell away – it was lower than the proposed roadway elevation – so a retaining structure was required. Before the roadway was built, one might expect that this “valley” was a path for water to drain down the hillside.

It is possible that the soil behind the retaining structure has become saturated (with native, up-slope water) and, as a result, has compacted under traffic.,.leading to the dips you see. It is also possible that the retaining structure's anchorage in the hillside has yielded somewhat...and so the retained soil has “dropped” to fill the larger retained region. We would expect to see “dishing” - long arcs of cracks in the asphalt – indicative of such movement. This is not clear in the photo. Lastly, a break in the road drainage system which would allow water to saturate the soils below the roadway's surface would contribute to the observed condition via a combination of the previous two methods.

here ya' go

Breaking… It’s ALL closed now. Oh, and the light at Hwy1/Coronado is STILL out. Should be fun. Wonder if the smart people will direct traffic at the light. Pffft

Tyler Durden

It's better to have the west bound lane closed rather than the east bound lane. It's like a music concert: You are free to leave, but no re-entries.

Cid Young

I do not consider it to be snarky when one can see that there has been NO maintenance of the drains that are along that K-rail divider since at least before summer. Please take note the pampas grass growing out of the grates, the next time you drive along there. There is very little pre-storm clearing of any storm drain systems in advance of rain events. Maybe CalTrans prefers to wait until there is a problem, rather than doing a little advance maintenance BEFORE wet weather begins, as we all know that will happen …. every year! And, since there really are no actual storm drains (or very few) on the Coastside, their jobs are easier than say, the South San Francisco Under passes on Hwy 101 that routinely flood in storms.

Coasting

Cid, neither of the two commenters made any mention of lack of maintenance of drains. All they chose to post were meaningless comments about tarps and duct tape. Those are not helpful.

Coasting

Folks, keep the snarky comments to yourselves. This is serious rain and problems were bound to occur. Make constructive suggestions, rather than propose facetious ones like using duct tape. Also, the issue isn't with the area with a tarp, rather sinking of the roadbed further west. Be helpful!

Kevin J

its so weird the tarp and sandbags didn't keep the road together

coastsidecurious

No duct tape?

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