Bending the River: Monitoring During Trenchless Tunneling


Bending the River is an infrastructural artwork that utilizes Los Angeles’s first water commons and demonstrates how the currency of water can create social capital and serve social needs. A percentage of water will be redirected through a diversion vitrified clay pipe running under the railway tracks to Metabolic Studio where the water will be lifted into a treatment wetland comprised of native plants. The regenerated water will then be distributed to a network of public parks.



Monitoring Program

Sixense Northern America was hired to carry out the displacement monitoring program that controls the potential impact of the trenchless operations on the ground, in adjacent structures, and Metrolink’s rail tracks.

Two solar-powered Automatic Total Stations (ATS) were installed to continuously monitor arrays of reflectors (prisms) installed along the alignment of the 1 m diameter and 49-meter-long tunnel. The monitoring data was delivered in near-real-time through our web platform Beyond Monitoring, including automatic alerts triggered if any of the threshold values were exceeded.



Bending the River: Project Takeaways

We are incredibly thankful for the opportunity to be a part of such a significant project, which has been in the making for over a decade.

The Bending the River project is unique and has been designed to enrich the lives of the local and native communities in ways that will have a lasting impact.

Thank you, Pacific Hydrotech Corporation, for your trust & support! Congratulations to Lauren Bon, METABOLIC STUDIO, and Geosyntec Consultants.

The completion of this project is a testament to the hard work, dedication, and perseverance of everyone involved. We look forward to seeing the positive effects it will have on the community for years to come.


Click here to discover more Sixense projects references (past & present).

Sixense Monitors Tunnel Construction Works on Highway 401 & 409

Sixense Northern America was retained by the Toronto Tunnel Partners (TTP) to perform environmental, geotechnical, and structural monitoring on North America’s busiest highway corridor (with 21 live lanes) throughout the construction of two new twin tunnels underneath the highways – all without disrupting the continuous traffic flow above.



We designed & deployed a monitoring system based on non-contact technologies (conventional and reflectorless robotic total stations, distance meters), horizontal shape arrays – 4DShape, as well as other structural and environmental instruments to monitor the deformation of the surface and the subgrade of the roadway, the rail tracks, and the subgrade of the rail corridor. Due to Sixense’s specialized devices, the monitoring system was able to achieve the high spatial density and high-frequency monitoring that was required on Highway 401 & 409, while in real-time minimizing interruptions of existing highway traffic and manual readings in heavy traffic areas.



After 6 months of baseline, construction was successfully completed after 2.5 years of structural improvement and excavation. The new tunnels will transform the transportation network in the Greater Toronto Area by providing a rail system that delivers two-way, all-day service every 15 minutes. The project was also recognized as the 2022 Project of the Year over $100 million by the Tunneling Association of Canada.


Some of our other tools that ensured the safety of the traveling public during the construction of this project on Highway 401 & 409 include: In-place Inclinometers, Piezometers, Tiltmeters, and Vibration & Noise Monitoring devices.


Resallience: One Unique Tool to Assess the Vulnerability of Assets

Our design offices specialized in climate resilience, Resallience, assisted the Deposit Fund Caisse des Dépôts (CDC) Habitat with its adaptation strategy to climate change. They joined forces with our engineering experts on existing structures to develop the first DPR platform (Climate Resilience Performance Diagnosis).

It is a decision support system composed of, on one hand, a hypervisor, powered by a geographical information system, and on the other hand, an analytical spreadsheet. The DPR allows you to assess the criticality level of historical structures to climate risks. It also analyzes the technical and financial risks of these contingencies on the components, the subsystems, and the systems of the groups of buildings. The DPR applies to all the property assets of CDC Habitat, close to 500,000 houses, and will allow clients to create plans of investments to restore history, adapt the design of the new constructions, and better adapt to climate change on the horizon of 2050.

This project comes within the scope of a partnership between CDC Habitat, the FFA Insurance (French Federation of Insurances, and the association of natural risks mission – MNR) created in 2000 by insurers in order to contribute to a better knowledge of natural risks.


Discover the article from CDC Habitat for more information.

Structural monitoring of the Normandy Bridge

The Normandy Bridge, a major structure that stands up to the elements

Since 1995, the Normandy Bridge is crossing the Seine estuary and connects Le Havre and Honfleur by a 2,141-meter long prestressed concrete and steel structure. It has a cable-stayed span of 856 meters. The deck of the structure accommodates 4 vehicular traffic lanes as well as bicycle and pedestrian paths. Its 184 stays, with up to 53 strands for the largest cables, ensure that the central steel deck is maintained for no less than 654 m above the navigation channel.

The durability of this structure, a symbol of French know-how in terms of Civil Engineering but subject to the winds and tides at the Seine estuary, is ensured by regular and rigorous maintenance. This maintenace is backed by the monitoring of the structure with a set of specific sensors but also by the periodic control of the structure’s and particularily the ageing of the stay cables


Increased surveillance of the structure to ensure its durability

Between 2011 and 2018, Sixense installed and maintained a monitoring system composed of about a hundred sensors: displacement, inclination, force in the stay cables, temperature, vibration of the structure, weather station and even breakage of stay cable wires. This system, which measures both the external stresses and the structural responses of the structure, enables a better understanding of the structure and anticipation of maintenance operations.

Since 2011, Sixense has also carried out periodic testing of the stay cables to determine their level of aging and check their residual structural strength. The Uscan process, patented jointly with the Gustave Eiffel University, works on the principle of ultrasonic guided waves to check the health of the strand wires in the areas where the stay wires are anchored.


Thanks to these continuous and periodic measurements on the sensitive componentss of the structure, the CCISE* can anticipate and schedule maintenance operations that will keep this masterpiece of French Civil Engineering intact for many years to come.


CCISE*: Seine-Estuaire Chamber of Commerce and Industry


Our SHM experts working on the Normandy bridge

Structural Deformation Monitoring of Hampton Roads Bridge-Tunnel Expansion Project USA

Structural Deformation Monitoring of Hampton Roads Bridge-Tunnel Expansion project using AMTS and high precision low cost GNSS.


The $3.8 billion Hampton Roads Bridge-Tunnel Expansion project is the biggest project in the Virginia Department of Transportation history which includes constructing twin bored tunnels west of the existing immersed-tube tunnel and bridge.

Sixense was chosen by the design-build team Hampton Roads Connector Partners (HRCP) (consists of Dragados USAFlatiron Construction, VINCI Construction Grands Projects and Dodin Campenon Bernard) to perform baseline deformation monitoring of the existing tunnel, approach walls as well as several facility buildings on the south and the north islands connected by the crossing from August 2019 to August 2020.

A robust near real-time deformation monitoring system was designed and implemented using 9 Sixense’s Cyclops automatic motorized total station (AMTS) systems, complemented by nearly 50 novel 4Dbloc, low-cost high-precision GNSS receivers and over 60 wireless tiltmeters.

In recognition of the high quality work performed by Sixense during the 1st stage baseline monitoring, a new contract for transition baseline monitoring into active construction stage monitoring was recently awarded to Sixense, in August 2020, with an expanded scope of monitoring work including a significant amount of AMTS, vibration monitors and other geotechnical instruments.

SHM on the Rio-Antirrio Bridge

The Rio-Antirrio Bridge in Greece is an exceptionally impressive structure built to endure extreme environmental conditions. Seismic and meteorological risks to its structural integrity must be continually monitored. Its operating concession holder Gefyra has entrusted Sixense with this task for more than 16 years.

From the construction phase onwards, the operating concession holder has needed to monitor the response of the bridge structure to its environment, and validate the assumptions made at the design stage. The ongoing monitoring of the aging structure enables decisions regarding whether the bridge can be reopened or requires maintenance closures following periods of extremely high winds or seismic events.


The Rio-Antirrio Bridge: a structure under the microscope 

EverSense ®, our Structural Health Monitoring System (SHM), was designed and implemented by our teams at the time of construction. Since it opened to traffic in 2004, the 1,000 data acquisition channels of this system have enabled Gefyra to record and characterize the behaviour of the structure and to detect changes in this behaviour, especially after exceptional events such as earthquakes or unusually high winds.

The monitoring system has been regularly maintained and upgraded since implementation. It now incorporates functions that enable real-time traffic management during seismic events or exceptionally high winds.

The EverSense system has made it possible to validate structural design data and coupled with the quality of data generated, has made it possible to allow traffic back safely onto the bridge promptly over 16 years of major environmental events.


The real-time monitoring system implemented by Sixense meant that we could analyse the huge amount of data needed to establish an overview of the structure and receive automated alerts immediately after the earthquake struck. The great advantage of the Sixense system is that it allows us to achieve significant improvements in safety, which is the most important thing from our perspective

Aris Stathopoulos, Structural Maintenance Manager at Gefyra SA/ VINCI Concessions for the Rio-Antirrio Bridge in Greece