Abstract
The WinCan VX inspection merging tool allows users to combined abandoned inspections from opposite ends of a pipe together into a single inspection. This can be useful for illustrating what the current condition of the pipe is in a user-friendly way, but at the same time may not always create an inspection record that meets the requirements of the currently selected standard.
Author
Steve Peregrine BEng Hons, Senior Technical Manager
Page Contents
Chapters
The Logic
There is one essential requirement that must be satisfied before inspection merging can take place – there must be at least one abandoned inspection from each end of the pipe in the current project.
There is no upper limit to the number of inspections, but always this lower limit. We cannot create a combined inspection if this status is not satisfied. There may be user scenarios where projects need to be merged before this test becomes true.
The default inspection merging options are designed to give the best possible engineering results for most standards, most of the time. Previous versions of WinCan had a much simpler inspection merging routine which crudely just stuck 2 inspections together, back to back. The result was that the new total length was assumed and was seldom correct, but some users have become used to this output, and so the option still exists to work this way, but it is an ‘opt-in’ feature that is off by default.
As with all data editing options in WinCan VX, good results from the Inspection Merger will only come from good input data. The most common error with abandoned inspections is very clearly visible on the pipe graph in VX and should stand out to users like a beacon.
Figure 1: Poor abandoned inspection data.
Look at the pipe graph and the data in Figure 1. See that the diagonal red line on the pipe graph is sitting on top of the manhole at the bottom of the image, and this is the really obvious indicator that something is wrong with this data that needs to be fixed.
Now look more closely at the distance of the abandoned code and the total length of the pipe and see that both numbers are the same at 78.96m. Ask yourself the question, “How can the inspection be abandoned if the length of the inspection is the same as the length of the pipe?”
If the whole pipe was inspected, then there should not be an abandoned code at the end.
This is bad data, but it is common with CCTV operators, when they have to abandon an inspection for any reason, and they comment that the don’t know how long the pipe is. This is seldom true and in most cases can be approximated on site, and in the case of electronic GIS data it can be defined very accurately from WinCan Map.
Figure 2: Good abandoned inspection data.
So, the pipe graph for a ‘good’ abandoned inspection will always look something like Figure 2. See now that there is a dotted section of the pipe after the red diagonal abandoned indicator and the comment ‘Not inspected length’ on the pipe graph. This visual clue on the pipe graph gives an immediate indication that data is most likely to be good.
See also that the distance measurement of the abandoned code is less than the total length of the pipe, so we now have more confidence that the inspection really was abandoned before reaching the end of the pipe.
So, to the basic rules of inspection merging, we must have at least one inspection from each end of the pipe that is abandoned. What might this look like in simple terms?
There is a slim chance that the two inspections reached the same point in the pipe, and the whole pipe was inspected, like here in Scenario 1 (where SA means ‘Survey Abandoned)’:
Scenario 1: Perfectly overlapped inspections.
However, it is more likely that during the site works, we actually ended up with results like any of these following scenarios:
Scenario 2: The two abandoned inspections did not reach anywhere in the middle.
Scenario 3: The two abandoned inspections overlapped and a part of the pipe was inspected twice.
Scenario 4: The inspection from one end was abandoned, but from the other end it was completed.
Scenario 5: There were two (or more) abandoned inspections from the same end.
Scenario 6: There was more than one abandoned inspection from one (or both) ends.
Now, let’s think about whether the resultant site works qualify the inspections for merging and if the do, then what will the status of the merged inspection be? Will it be complete or abandoned?
Scenario | Queries |
|---|---|
1 | Do the inspections qualify for combining? Yes, because there is at least one abandoned inspection from each end. What will be the inspection status of the combined inspection? Complete, because the whole pipe has been inspected. |
2 | Do the inspections qualify for combining? Yes, because there is at least one abandoned inspection from each end. What will be the inspection status of the combined inspection? Abandoned, because the whole pipe has not been inspected. |
3 | Do the inspections qualify for combining? Yes, because there is at least one abandoned inspection from each end. What will be the inspection status of the combined inspection? Complete, because the whole pipe has been inspected. |
4 | Do the inspections qualify for combining? No, because there is only an abandoned inspection from one end. The inspection from the other end is complete. |
5 | Do the inspections qualify for combining? No, because there are no abandoned inspections from one end of the pipe. |
6 | Do the inspections qualify for combining? Yes, because there is at least one abandoned inspection from each end. What will be the inspection status of the combined inspection? Abandoned, because the whole pipe has not been inspected. |
Consider a little further Scenario 6. When we combine inspections, we combined two inspections into one. We cannot combine three or more inspections because the resultant combined inspection will just be mess of observation codes and will therefore be inappropriately scored.
So, we must decide which of the two inspections from the upstream end of the pipe will be used to combine with the inspection from the downstream end of the pipe.
The default rule is quite simple – the inspection merger always takes the ‘most recent’ inspection from each end when it decides which inspections to use for combining. So, it considers the inspection date and time in the header. So, in this case, inspections 2 and 3 will be combined, because the 2nd inspection from the upstream end is the most recent.
This logic does not pay any attention to the length of the inspection, so even if the 1st inspection went further and was longer than the 2nd inspection, the most recent will always be taken by default. It is considered to be the most up-to-date information regarding the state of the pipe. Later we will see that there is an opportunity in the inspection merger settings to overrule this automated behaviour.
Now let’s think about Scenario 3 a little more. As we know, there is a section of the pipe in the middle that has been inspected twice, so what are we going to do with all of the observation codes from the two inspections in this zone? If we add them all to the combined inspection, then we may be recording the same defect twice, and this can drive bad scoring results.
After the inspection merger has figured which two inspections it is going to merge, it always takes the most recent inspection out of the two up to its end (its own abandoned distance), and then takes the other inspection for the remainder of the pipe. This rule cannot be overridden and is always applied.
So, in summary, we have first the golden rule for inspection combining:
There must be at least one abandoned inspection from each end of the pipe.
Then, there are rules applied during the merge:
The most recent inspection is always taken from each end of the pipe.
Where there is an overlap, the most recent of the two is taken in its entirety, and then the remainder of the pipe observations come from the other inspection.
As you can see, there are a number of data values at play here that are used to create a sound engineering solution to the inspection merging.