New video examines the geotechnical assessments being made on US 89

Check out the video above. Not only does it give an up-close look of what’s happening at the US 89 site, it also provides us with a few new, interesting geotechnical terms, including inclinometers, extensometers, LiDAR and DTM....

Inclinometers
If you’ve been reading the blog all this week, you’ll already be familiar with how inclinometers work (if you haven’t, you can catch up). It’s fascinating to see them being used out in the field, don’t you think?

Extensometers
ADOT Deputy State Engineer Steve Boschen says the tool offers “a crude way to measure how much the slope is moving.”

Engineering Geologist Nick Priznar further explains how they function.

“This is a fairly simple device that has a quarter-inch wire that’s anchored at the toe of the slope,” he says in the video above. “It bridges the tension crack and comes up here over the pulley and we have a 30-pound weight and it’s registered to a scale on the side of the tripod. If there’s any relative movement in the direction of the wire, it’s reflected in movement up and down along the side of the scale.”

You can get more views of the extensometer at work.

LiDAR
LiDAR is a three-dimensional laser scanner. The sophisticated surveying instrument has a wide variety of applications.

It’s used regularly for field surveys, but on the US 89 site, LiDAR is being used to help map the landslide.

LiDAR, by the way, stands for Light Detection And Ranging.

DTM
One more term we heard in the video is DTM – digital terrain maps (or models).

Long-time readers of this blog might remember we mentioned DTMs in this post on photogrammetry.

Digital Terrain Maps give engineers a three-dimensional view of what the surface of the ground looks like.

That’s not it...
In the weeks to come, we’ll continue to keep you updated with information on US 89. Look for more videos – and geotechnical terms – in the near future.