Evaluation and Condition Monitoring
Laser scanning can be used as a condition evaluation and monitoring tool to evaluate the condition of the tunnel surface prior to any detailed examination by engineers. Scans are taken throughout the tunnel and registered to form an overall pointcloud related to a specified grid.
The data can then be presented in several ways however we have found that our tunnel maps are the most convenient representation of the tunnel in a 2D format and an example is shown here.
The tunnel map drawing shows how we can un-wrap a section of the tunnel (usually around 20m in length and excluding the rail bed) and show it in a 2D format, superimpose a grid and relate the data to the internal tunnel chainage.
Scantech International has carried out many such surveys and produced dozens of the tunnel maps and recent examples include :
- Perran Tunnel for Dyer and Bulter
- Amphill Tunnel for COWI
- Kilsby Tunnel for J Murphy
- Linsdale Tunnel for J Murphy
- Rise Hill Tunnel for Inspectahire/Amco
Using laser scanning for Tunnel Condition Evaluation and Monitoring has several main advantages when used in conjunction with manual evaluation :
- The tunnel maps can be examined in the office to identify areas of concern
- Areas of concern highlighted in the office environment can be examined on site during the possession
- Reduced the number of site visits to manually examine the tunnel
- Reduces strain from looking upwards to examine long stretches of the tunnel crown
- Saves time in producing the report
- Reduces the cost of the examination