Laser Tunnel Scanning System (LTSS)

PavemetricsTM Laser Tunnel Scanning System (LTSS) uses multiple high-speed laser scanners to acquire both 2D images and high-resolution 3D profiles of tunnel linings.

The LTSS is 100 times faster and 10 times more accurate than typical LIDAR technology; it can scan a 12m tunnel vault at 1-mm image resolution and 3D data at acquisition speeds of up to 20km/h. Larger surfaces can be captured through multiple passes (and the images and data “stitched”) or scanning width can be increased through the addition of sensors.

Once digitized, the tunnel data can be viewed and analyzed offline by operators using multi-resolution 3D viewing and analysis software that allows for high-precision measurement of virtually any tunnel feature.

Automatic analysis software is also available to detect and rate the condition of joints, faulting, cracks, and degraded concrete as well as points of water ingress in the tunnel lining.

Highly Accurate

Our LTSS system can acquire 120,000,000 3D- and 2D-image points per second with a 0.5mm accuracy compared to typical LIDAR accuracies of 5.0mm for just a few 100,000 points.

A Proven Technology

LTSS technology was used to scan high-speed-train rail tunnels such as the 28-km-long Spanish Guadarrama Tunnel in full 1-mm resolution (x,y,z) in just 3 hours.

It has also been used to acquire data on the Tokyo Metro System in Japan. Vaults are scanned one half going forward and the second half coming back.

Fast Data Collection

The standard LTSS configuration (6 sensors) allows for the scanning of a full 12m of tunnel-surface perimeter in a single pass. Larger surfaces can be captured through multiple passes (and the images and data “stitched”) or scanning width can be increased through the addition of sensors.

Automated Analysis Software

Automatic analysis software is available to detect and rate the condition of joints, faulting, cracks, and degraded concrete as well as wet-and-humid-area tunnel linings.

See it in Action

Click on the movie below to see the capabilities of the LTSS.

Key Features

  • Full-vault scanning
  • 1-mm-resolution images and 3D data
  • 100 times faster and 10 times more accurate than LIDAR scanning
  • Measurement of tunnel features with sub-millimeter accuracy
  • Visualization of 1-mm surface defects from any point of view without leaving the office
  • Scanning speeds of up to 20km/h
  • Automatic analysis software of voussoir-type tunnels available
  • Rail scanning option available

Specifications

  • 30,000 Hz scanning frequency
  • 1 mm longitudinal scanning interval at speeds up to 110 km/h or 2 mm longitudinal scanning interval at 200+ km/h
  • 1 mm transverse resolution
  • 0.5 mm vertical accuracy

Use of 3D Scanning Technology for Automated Inspection of Tunnels
Authors: John Laurent (Pavemetrics), Richard Fox-Ivey (RFI Consulting Services), Fernando Sanchez Dominguez (Euroconsult Group), José Antonio Ramos Garcia (Euroconsult Group)
Abstract: This presentation will explore the application of 3D laser scanning technology to the activity of tunnel inspection. The discussion will include a discussion of the practical achievable levels of data precision and accuracy obtained during testing the Guadarrama and Regajal rail tunnels in Spain.


Mobile Inspection System for High-Resolution Assessment of Tunnels
Authors: M. Gavilán, F. Sanchez, J.A. Ramos and O. Marcos (Euroconsult Group)
Abstract: This paper presents a novel system for tunnel lining inspection, Tunnelings, which allows for high-resolution surveys at speeds up to 30km/h. This rapid tunnel condition assessment capability makes it possible to perform long tunnel inspections on a regular basis, and to assist geotechnical engineering and tunnel management, allowing for preventive and operational maintenance of large infrastructures. Tunnelings uses several lasr-cameras units and acquires intensity images and 3D profiles with an accuracy depth of 0,5mm and a longitudinal and transverse resolution of 1mm. The laser-cameras units can be installed on a bimodal (road-rail) all-terrain truck which provides rapid travel speeds and flexibility to cope with different types of tunnels and infrastructures. Moreover, they can also be installed on other kinds of vehicles, as well as in a standard railway wagon. A computer vision-based software helps with the evaluation of the tunnel condition, allowing for the detection of cracks and areas with missing lining or chipping, dampness and running water, areas with poorly assembled segments, protuding edges and poor workmanship, as well as the assessment of tunnel installations.