Tunnel & rail scanning

In recent years, the requirements and high standards of quality, safety, environment or cost-effectiveness placed upon public construction have grown significantly. For clients, designers and contractors, the right information at the right time is the key to success. Laser Scanning in railways and tunnels is being used at a rapidly-increasing rate and becoming the quickest, safest and most accurate approach to document valuable 3D information for transportation-related surveys. Reality Measurements Inc. is an established engineering consulting company providing 3D precision measurement laser scanning for the acquisition, analysis and provision of valuable information for railway track and tunnels for new construction, refurbishment or monitoring. Our thorough knowledge of the operational functionality of laser scanners and laser scanning methodologies provides us with the expertise to obtain the highest possible accuracy of data collected from the laser scanner.

Pairing a 3D Laser Scanning Trolley System with the state-of-the-art Imager 5010X Laser Scanner, railway tracks and tunnels can be quickly laser scanned with extreme accuracy. With higher train frequencies, higher speeds and greater safety concerns, there are new challenges for track maintenance, reliable route documentation and comprehensive surveying data requirements with appropriate precision results in real time.

Some possible applications are as following.

Railway / Subway track

  • Existing tracks geometry is recorded and documented.
  • Complete clearance analysis.
  • Quality checks can be undertaken.
  • Integrate track fix points and a geodetic railway network.
  • Absolute track position, cross-sections and alignment.
  • Clearance analysis as a function of the track radius for the planning and dimensioning of new tracks whereby all objects protruding into the clearance analysis profile are detected with coordinates and exported to a spreadsheet.




  • Modify existing tunnels.
  • Tunnel clearance and surface checks, profile measurements.
  • Individual localized checks to detect specific encroachments.
  • For planning and renovation as well as monitoring, a complete clearance analysis can be provided for construction projects.
  • Inventory surveying can be done to record surface features as well as geometric data for damage registers, and object mapping.
  • Comparisons of surveys for ongoing monitoring.



Inventory surveying

  • Laser scanner measurements for inventory surveying and assessment.
  • Structural condition assessment of tunnel or rail system, damage mapping and as-built documentation of structures.
  • Acquire surface structures for crack detection at .3 mm.
  • Object mapping.
  • Statistical evaluations.
  • Database of mapped objects.



GRP system FX

  • GRP 1000 surveying is for determining the rail geometry or position (as built vs design in real time): Cant, track gauge, track marks, absolute rail position, curvature, track twist, super elevation.
  • GRP 3000 used for clearance and to route as-built, and for collecting encroachments: position of track axis, calculation to design axis, cross-sections, open track and tunnels.
  • GRP 5000 used comprehensive infrastructure documentation such as for track alignment: 33 profiles with 10,000 points per second, calculation to design axis, graph as clearance map, grayscale image and geometry, for tunnels, bridges, underpasses and overpasses.



Imager 5006

  • Measurements of infrastructure without tracks (without a trolley system):
    • Retention of evidence
    • Acquire surface structures
    • Crack detection
    • Road tunnels
    • Hydropower tunnels
    • Shafts
  • Scanner measurements of narrow objects:
    • Deformations
    • Retention of evidence
    • Acquire surface structures
    • Hydropower
    • Buildings
    • Shafts
  • Scanner measurements in road tunnels:
    • Clearance map for heavy transports
    • State assessment
    • Object Mapping