Maintenance and Inspection
The regular upkeep and inspection of mitigation measures is an important aspect of asset management. A structure is at its peak level of effectiveness immediately following installation, after which it decreases with time. Varying degrees of damage and the accumulative effect of damages over time can render the measure non-functional. This mean elements at risk are no longer protected, but it could also have legal implications such as where buildings were constructed/occupied on the condition of rockfall mitigation measures being in place and functional.
The graphic below depicts the general affect of carrying out routine maintenance. The red line shows the decay of a measure given no maintenance. At some point in time the wear and tear on the structure will bring its functionality below a critical state where repairs are no longer viable and replacement is necessary. The blue line shows periodic maintenance that raises the functionality of the system and prolongs its lifespan. With this said, repairs will not always bring the functionality back to its original state and so a steady but much slower decline in overall functionality occurs and a critical state is still reached at some point.
The guideline details five types of inspection protocols to establish the state of a structure and are a tool for implementing maintenance. The types and frequency of inspections are outlined in the table below for the various consequence class ratings. The five protocols are First Inspection (FI), Ongoing Monitoring (OM), Control (C), Audit (A) and Special Inspection (SI). These inspections result in specific documentation outlined in the guideline and the assessment of a status level.
|Inspection Interval CC3/CC2/CC1 [years]
|FR (First Recording)
|The initial inspection and documentation for a newly constructed measure during which a C-protocol is also carried out
|OM (Ongoing Monitoring)
|A regularly undertaken inspection to determine the level of impairment of function due to high-frequency events
|A detailed visual account of the condition and functionality of the system as a whole as well as individual components
|A detailed inspection conducted when a Control inspection was unable to ascertain the structures condition and may include special testing and investigative techniques
|SI (Special Inspection)
|An inspection carried out as necessary, usually after an exceptional events (e.g. storm, avalanche, accidents, etc.)
The mitigation measure’s status with respect to load bearing capacity and serviceability are divided into five classes as below. The status level also indicates a basic prediction of the time frame under which repairs should be carried out.
|Timescale for Implementation of Maintenance
|Examples of Damages
|0 (structure no longer necessary)
|structure was replaced with other measure or no longer required
|no visible damage
|1 (very good preservation)
|no restrictions on functionality
|no visible damage
|2 (good preservation)
|minor restrictions on functionality
|possible light signs of wear, light corrosion
|3 (sufficient preservation)
|minor damage with acceptable functionality
|plastically deformed nets, visibly deformed brake elements
|4 (bad preservation)
|significant damage with restrictive functionality
|exposed anchorages, kinked micropile anchors, deformed posts, severely deformed brake elements, reduced nominal height, rope failures, destroyed shackles/wire rope clips, backfilling of net, cracked welds
|5 (destruction/total loss)
Please refer to the original guideline for more detailed information about the inspection protocols, how they are carried out and who is eligible to conduct them.
What level of risk is there?
How is a design block selected?
What system capoacity is sufficient?
What system height is required?
How is an anchor verified?
What other performance criteria are there? Click Here
How can the system be safely adapted to a site?
What recommended maintenance protocols exist?