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 consists 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, are 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.


GEO’s web-based applications processed the measurements, checked for alarm conditions, and made the data available on a project website.

M Street WMATA Tunnel

GEO is 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.