Roadwork: Vincent Chu Answers
Can all utility detectors detect the depth of utilities?
In Hong Kong, underground utility detectors are normally of two types:
- Electromagnetic detector and
- Ground Penetrating Radar (GPR).
Both the alignment and depth can be found in active mode while only alignment can be found in passive mode.
The electromagnetic detectors available in market can detect utilities up to depth of 3m.
It has the advantage of locating both the depth and alignment of utilities.
More importantly, it can detect both metallic and non-metallic utilities.
However, it suffers from the disadvantage that it is quite expensive and interpretation of data is not simple. Reference is made to LD, DSD (2000).