I was consulted by the HSR team about 2011 as their control was falling apart and land surface elevations along the alignment were dropping rapidly from when they were mapped. They asked me what they should "do" about it? I told them that they either move the alignment (going almost right through the El Nido Bowl) or acquire a much wider right-of-way footprint than the original design called for because the profile of the rails had to be built where it was designed to be built, which meant they were going to have a much taller/wider base to reach the the ground surface when they finally build it. Of, course, that also meant huge change orders and wouldn't solve the problem going forward if the subsidence continued, which was likely. At that point it was about 2.5' in the worst areas, but across the valley to the west is where the "famous" picture of Dr. Joe Poland was taken standing next to a utility pole marking where the land surface had been 1925 and 1977. A total of about 29'.
The best option is to not build it at all, but I'll refrain.
https://www.usgs.gov/media/images/location-maximum-land-subsidence-us-levels-1925-and-1977
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