Project : MBTA Green Line Extension

MBTA and White/Skanska/Kiewit (WSK) -- Cambridge, MA

The Green Line Extension project is a major expansion of the MBTA’s Green Line through Cambridge, Medford, and Somerville, Massachusetts involving both the Fitchburg Line and Lowell Line railroad corridors. It involves approximately four and a half miles of rail corridor expansion and re-construction work, as well as the construction of seven new commuter passenger stations.

CHA was awarded a contract by WSK joint venture to review and verify the existing horizontal and vertical survey control as provided for the project and to further densify upon that control in the interest of preserving it for the life of the project.

Services provided by CHA:
  • Field reconnaissance and recovery of existing horizontal and vertical control points
  • Preparation of survey plan
  • Installation of supplementary primary horizontal and vertical control points
  • GNSS static survey
  • High precision vertical control survey (First-Order, Class II)
  • High precision horizontal control survey (First Order)
  • Computational work
    • Control network design and computer simulations
    • GNSS and terrestrial data pre-processing and reductions
    • Control network least squares adjustments and analysis
    • Analysis and comparison of the existing control used during the design phase
  • Preparation and submittal of a comprehensive survey final report