LA Metro Regional Connector Transit Project

SECTOR: Tunnelling

Los Angeles, California


ShapeArray reduces uncertainty in soft ground tunnelling

ShapeArray provided more precise ground movement data above the tunnel shield during the progression of an Earth Pressure Balance Tunnel Boring Machine

The Regional Connector Transit Project will connect two existing underground rail lines in Los Angeles. Completion of the Los Angeles County Metropolitan Transportation Authority’s (Metro) design-build project is expected in 2021. The result will be a new underground light rail system, approximately 3 kilometres long, to connect the Metro Gold Line to the 7th Street/Metro Center Station.

The $1.756 [1] billion project includes the construction of three underground stations, approximately 1.8 km of twin tube bored tunnel, and approximately 1.5 km of cut and cover tunnel, amid Los Angeles’ busy city streets. A tunnel boring machine (TBM) created the twin tube portion, using the technique of pressure balanced mining. Construction officially broke ground in 2014.

During project planning, Metro performed a building and utility protection assessment, which determined several buildings were at risk from the planned tunnelling activity. Engineers determined a limit of 13 mm of maximum movement for structures and utilities. In response, Metro developed a comprehensive monitoring strategy to allow tunnelling under existing buildings and utilities with very low ground cover.

Metro installed ShapeArray 1 m over each of the twin tunnels to monitor the path of the TBM. With ShapeArray’s sensorized segments running along the centreline of the TBM’s path, the operation parameters of the TBM could be confirmed or modified in real-time. A multipoint borehole extensometer (MPBX) was also installed 400 mm vertically and 300 mm laterally from the SAAX model ShapeArray. Data from the two measurements agreed to better than 2 mm as the TBM passed underneath [2].

Photo credit: Photos courtesy of Joe Linton/Streetsblog LA

[1] Los Angeles County Metropolitan Transportation Authority, “Regional Connector Transit Project Overview,” 2017. [Online]. Available:

[2] Hansmire et al., “Challenges for Tunneling in Downtown Los Angeles for the Regional Connector Project,” Proceedings of the World Tunnel Congress 2017. Bergen, Norway, 2017.

Use of the [ShapeArray] has further defined the ground and TBM interactions. The [ShapeArray] has also eliminated some of the uncertainty associated with soft ground tunnelling such as face stability and location of lost ground [2].”
William H. Hansmire
WSP Parsons Brinckerhoff
  • 1993

    The Beginning

    Measurand is established in Fredericton, New Brunswick
  • 1994

    Bend sensor development

    Measurand develops and patents fiber optic bend and position sensors for the medical and automotive sectors

    U.S. Patent 5,321,257

  • 1995

    Canadian Space Agency

    Receives funding from the CSA to develop sensor technology that ultimately leads to invention of ShapeTape

    U.S. Patent 5,633,494

  • 1999

    Patent on fiber optic sensor

    Measurand receives patent for "Fiber Optic Bending and Positioning Sensor" issued June 29, 1999

    Canadian Patent 2,073,162

  • 2001

    ShapeTape & ShapeHand debut

    Measurand designs and develops innovative motion capture technology

    U.S. Patent 6,127,672, 6,563,107

  • 2002

    Measurand Attends the ICPMG

    First contact with the geotechnical sector at the International Conference on Physical Modelling in Geotechnics (ICPMG)
  • 2004


    Design patent application sent about a new product designed to meet the specific needs of the geotechnical industry

    U.S. Patent 6,127,672, 6,563,107

  • 2005-08


    Measurand debuts ShapeWrap motion capture technology for the film and animation industry

    U.S. Patent 7,296,363

  • 2006

    Malibu installation

    ShapeAccelArray installed for ground monitoring for the first time​ in Malibu, CA

    Canadian Patent 2,472,421

  • 2007


    Suite of instrumentation developed for motion capture within Magnetic Resonance Imaging (MRI) machines

    U.S. Patent 7,296,363

  • 2011

    SAAScan launched

    Built for rapid deployment and repeated use

    Canadian Patent 2,472,421

  • 2014

    SAAX launched

    Purpose-built for heavy-duty horizontal installation

    Canadian application 2,815,199 & 2,815,195

  • 2017

    SAAV launched

    The only geotechnical instrument with a patented cyclical installation method

    Cyclical Sensor Array, Canadian application 2,815,199 & 2,911,175