M-Street Excavation & Tunnel
![M Street Excavation Left M Street Excavation](https://www.geo-instruments.com/wp-content/uploads/mstreet-left-525.jpg)
GEO monitored a 32-foot deep excavation and a WMATA metro tunnel adjacent to the excavation in Washington DC.
![M Street Excavation Right M Street Excavation Right](https://www.geo-instruments.com/wp-content/uploads/mstreet-right-525-1.jpg)
The SOE consisted of drilled soldier piles braced with whalers and rakers. GEO’s technician can be seen on the wall.
![M street excavation prisms M street excavation prisms](https://www.geo-instruments.com/wp-content/uploads/lee-with-prisms.jpg)
Monitoring prisms, a few visible in this photo, were mounted at the top of each pile around the entire perimeter of the excavation.
![satellite-with-metro M Street Excavation sat view](https://www.geo-instruments.com/wp-content/uploads/satellite-with-metro.jpg)
One wall of the excavation was located within 33 feet of a WMATA metro tunnel. The tunnel alignment is shown in blue.
![M street Planview with AMTS icons M street Planview with AMTS icons](https://www.geo-instruments.com/wp-content/uploads/Planview-350-with-topcons.png)
The spatial positions of the prisms were measured by two AMTS systems. Changes in the position of a prism indicated movement.
![mstreet-westwall-Z mstreet-westwall-Z](https://www.geo-instruments.com/wp-content/uploads/mstreet-westwall-Z.gif)
GeoCloud web servers processed the measurements, checked for alarm conditions, and made the data available on a project website.
Existing WMATA Tunnel
![M Street WMATA Tunnel M Street WMATA Tunnel](https://www.geo-instruments.com/wp-content/uploads/m-street-tunnel-with-prisms.jpg)
GEO also monitored the WMATA tunnel near the site. Above, you can see the reflections from prisms mounted on the tracks, springlines, and crown of the tunnel.
![M-Street WMATA Tunnel Planview M-Street WMATA Tunnel Planview](https://www.geo-instruments.com/wp-content/uploads/m-street-amp-planview-of-tunnel.png)
This plan view shows a 350 foot span of the tunnel along with XYZ displacements calculated from measurements from each prism.