Coastal Civil/Structural Engineering - Infrastructure Stability

[Astronuc]

Once again, a part of a highway along the coast in California has collapsed. Folks like having a view of the ocean while driving - although the driver is supposed to be watching the road for curves, wildlife and oncoming traffic.

Hundreds Stranded as Part of California Coastal Highway Collapses
https://news.yahoo.com/hundreds-stranded-part-california-coastal-101901797.html

Who thought is a good idea to build a highway on a sandstone cliff, and it's hardly sandstone, but more like compacted ground, which when wet, or rather soaked, by rain is likely to collapse - as is not uncommon in such area along the west coast. There was a retaining wall, but much of the ground underneath fell away.

I suspect that at one time, there was more cliff there than there is now. In time, the cliff will likely reach the inland side of the road. A combination of wave action and periodic heavy rains means the coast line will move inland eventually, as California is learning the hard way.

 

[berkeman]

Yeah, 3 roads in a big city park next to us here in the foothills above Silicon Valley have been washed out partially by the big rain storms of the past few years. Two of them have been repaired but are still closed to auto traffic, and the 3rd is not repaired but has 1-way traffic controls via automated signal lights now. It will be pretty hard to repair since part of the road collapsed into the creek that runs right next to the road (much like the picture in your post above, just not as far down to the creek).

Hopefully road planners will do a better job going forward thinking about where to run new roads...

 

[Baluncore]

One thing is certain, cliffs represent an active erosion landscape. The slope of the land determines the energy available for erosion when it rains. Given time, the sea will undermine whatever is built.

The coast road should be restricted to local access. Transport links should be located inland, where risk and engineering costs are less, as there is more ground stability.

 

[Tom.G]

Hey folks!
This is California, the Earth here moves in all 3 dimensions without notice. We deal with it.
(It helps build our hubris, you see. )