M-Street Excavation & Tunnel

M Street Excavation

GEO monitored a 32-foot deep excavation and a WMATA metro tunnel adjacent to the excavation in Washington DC.

M Street Excavation Right

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

Monitoring prisms, a few visible in this photo, were mounted at the top of each pile around the entire perimeter of the excavation.

M Street Excavation sat view

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

The spatial positions of the prisms were measured by two AMTS systems. Changes in the position of a prism indicated movement.


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

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

This plan view shows a 350 foot span of the tunnel along with XYZ displacements calculated from measurements from each prism.