Merrimack Bridge

MassDOT rehabilitated the Merrimack River Bridge, strengthening the superstructure and mitigating scour around the bridge piers.

Comeau Bridge

GEO placed an automated total station (AMTS) on the nearby Comeau bridge to monitor the stability of the piers of the Merrimack bridge.

Comeau Bridge AMTS

The AMTS measures angles and distances to prisms installed on the piers. The GeoCloud server provided least-squares adjustments and web access to data.


GEO technicians installed prisms, crackmeters, and an automated vibration monitor (AVM) on each pier. Instruments are powered by batteries and solar panels.

L-bar prism on bridge pier

Prisms are used with the AMTS to monitor X, Y, and Z displacements. AVMs will monitor vibration levels during installation of sheet piles.

Comeau Bridge AMTS

Another view of the AMTS on Comeau Bridge. The blue box houses a controller, power supply, batteries, and communications equipment.