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Introduction

There is often misconception regarding the depths of objects, the object types and how they are handled. This document attempts to clarify and explain how WinCan VX works with these data values in all standards.

For the purposes here, sections and laterals are the same thing. They are just pipes below the ground level.

In all pictures here, the top horizontal black line is the cover level and it does not have to be the same for both nodes, but is shown here this way for simplicity.

The team at WinCan STRONGLY recommends using the WinCan VX Data Validator to check the quality of imported and user entered data before carrying out 3D Measurements or complaining that the application is not working correctly. In most cases, it is fine and the problem is missing or badly applied data values where there is little consideration to the object types and where the correct data must exist.

We cannot be responsible for bad results caused by poor data from a third party.

First here, we will consider a simple drainage layout and then a complex system, but please be clear - the principles described here are EXACTLY the same for both systems.

The Simple System

Consider this simple drainage system:

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Here, we have 2 nodes and 3 pipes, all flowing nicely downhill, like regular manholes and drains.

First, we must consider the different elements in play:

We must be clear that the orange zones are nodes and the green zones are pipes, sections or laterals. This colour code will continue for the remainder of this document.

In WinCan VX, we have data entry areas for Sections/Laterals and for Nodes. The data for the green zones is always in the Sections/Laterals and the data for the orange zones is always in the Nodes.

Sometimes, the values my be the same in both data areas, but not always. This is where we consider the complex example later.

So, if we wish to measure the depth of the nodes, we can do this by making these measurements and entering the data into the Node Depth field in the Node area of WinCan VX.

And, if we wish to measure the depths of the ends of the pipe, we must do this in the Section/Lateral area and we can do it twice, once for the upstream end of the pipe and once for the downstream end of the pipe, like this:

In a real drain situation like this, it is likely that the depth of the left node is the same as the upstream end depth of pipe B, and the depth of the right node is the same as the downstream end depth of pipe B. This is why this is a simple example of a drainage layout.

But remember, the correct data must be entered into the correct places to get the best results. The logic that sits behind this is not special for any one territory or standard around the world. It is the same for everyone everywhere.

The Complex Example

Now let us consider the complex drainage system and think clearly about how this data must be entered into WinCan VX. Here is the drainage system:

And here are the pipe and node zones, the same as before:

And again, let’s consider the depths of the manholes for the node data here:

And the upstream and downstream depths of the ends of the pipes for the Section/Lateral data:

You will see now that the pipe depths and the node depths are very different, and we must be clear which depth is being entered into which area of WinCan VX

Simple Worked Example

Take the simple example and let us enter the following data.

Manhole data:

• Left Manhole Cover Level (DMP in Germany) = 42.1m above sea level

• Right Manhole cover Level (DMP in Germany) = 42.1m above sea level. So the two manholes have the same cover level because this is a simple example.

• Left manhole depth = 1.6m

• Right manhole depth = 1.8m

• Left manhole invert level (SMP in Germany) = 42.1 - 1.6 = 40.5m above sea level

• Right manhole invert level (SMP in Germany) = 42.1 - 1.8 = 40.3m above sea level

Pipe data:

• Left Manhole Cover Level (DMP) = 42.1m above sea level

• Right Manhole cover Level (DMP) = 42.1m above sea level (so the two manholes have the same cover level because this is a simple example)

• Pipe B Upstream Depth = 1.63m

• Pipe B Downstream Depth = 1.78m

• Pipe B Upstream invert level = 42.1 - 1.63 = 40.47m above sea level

• Pipe B Downstream invert level = 42.1 - 1.78 = 40.32m above sea level

Conclusions:

• The cover levels of the 2 manholes are the same.

• The right manhole is deeper than the left manhole. We can see this because the right manhole is deeper than the left manhole, but more importantly, the right manhole invert level (SMP) is lower than the left manhole invert level (SMP).

• Pipe B flows downhill because the upstream end of it is higher (40.47m) above sea level than the downstream end (40.32m)

Complex Worked Example

Take the complex example and let us enter the following data.

Manhole data:

• Left Manhole Cover Level (DMP in Germany) = 42.1m above sea level

• Right Manhole cover Level (DMP in Germany) = 42.85m above sea level. So, the downstream manhole cover level is higher above sea level than the upstream cover level.

• Left manhole depth = 1.62m

• Right manhole depth = 3.64m

• Left manhole invert level (SMP in Germany) = 42.1 - 1.62 = 40.48m above sea level

• Right manhole invert level (SMP in Germany) = 42.85 - 3.64 = 39.21m above sea level

Pipe data:

• Left Manhole Cover Level (DMP) = 42.1m above sea level

• Right Manhole cover Level (DMP) = 42.85m above sea level. So, the downstream manhole cover level is higher above sea level than the upstream cover level.

• Pipe B Upstream Depth = 1.64m

• Pipe B Downstream Depth = 2.81m

• Pipe B Upstream invert level = 42.1 - 1.64 = 40.46m above sea level

• Pipe B Downstream invert level = 42.85 - 1.78 = 40.03m above sea level

Conclusions:

• The cover levels of the 2 manholes are not the same.

• The right manhole is deeper than the left manhole, not because the right manhole is deeper than the left manhole, but because the right manhole invert level (SMP) is lower than the left manhole invert level (SMP)

• Pipe B flows downhill because the upstream end of it is higher (40.46m) above sea level than the downstream end (40.03m)

• The downstream end of Pipe B is not at the base of the manhole because the downstream invert level of the pipe is at 40.03m above sea level but the base level of the right manhole is at 39.21m above sea level, so the end of the pipe is 40.03 - 39.21 = 0.82m above the bottom of the manhole.

Question:

Do we really see manholes like the one on the right where the pipe is not at the bottom?

Yes, there can be manholes where the incoming pipe is not at the top and the outgoing pipe is at the bottom and there can be objects like the one shown where both pipes are not at the bottom and these are commonly found on rainwater system like highways to catch the silt that runs off the road ready for collection. These can be known as catchpits, silt interceptors or silt traps etc.

What Does WinCan VX Do with 3D Measurements?

VX handles all this in all standards and all territories in exactly the same way, and these methods will not be changed. This also applies to 3D measurements.

The basic information is that WinCan VX considers the asset that is being inspected or measured and then works out Z levels backwards from there, but there are some different scenarios based on whether the cover level of the node is known or not.

Manhole cover level is not known:

Imagine we are making a 3D measurement upstream along a Section/Lateral to a node and the cover level is not known for the node.

So, to summarise, WinCan VX will calculate the cover level from the end of the test using the first one of these that is true:

1. The pipe depth at the end of the measurement is greater than zero.

2. The manhole depth at the end of the measurement is greater than zero

3. 1m

Manhole cover level is known:

If the manhole cover level is known and has been specified in the data by the engineer or in the import file, then we will not change it because it has been explicitly specified by the user or client, so we must handle the shape of the measurement in a slightly different way in the following order:

1. If the pipe depth at the end of the pipe is known, then we rotate and scale the 3D measurement (i.e. the end of the pipe) to fit the specified node cover level minus the pipe depth at the end of the pipe.

2. If the pipe depth is not known then we rotate and scale the 3D measurement (i.e. the end of the pipe to fit the specified node cover level minus the node depth.

3. If the node depth is not known, then we rotate and scale the 3D measurement (i.e. the end of the pipe to fit the specified node cover minus 1m.

Key Database Fields

• Pipe Upstream Depth measured down from Cover Level:

  • SECTION.OBJ_FromNodeDepth

• Pipe Downstream Depth measured down from Cover Level:

  • SECTION.OBJ_ToNodeDepth

• Node Depth measured down from the Cover Level:

  • NODE.OBJ_DepthToInvert

• Pipe Upstream Invert level measured from sea level:

  • SECTION.OBJ_FromNodeInvert

• Pipe Downstream Invert level measured from sea level:

  • SECTION.OBJ_ToNodeInvert

• Node Invert level measured from sea level:

  • NODE.OBJ_NodeInvert

Note - all the invert level fields can be calculated in WinCan VX by clicking the ‘Calculate Invert Levels’ button in the Tools ribbon. The invert levels above sea level will be calculated where the other two parameters required to make the calculation are both not null.

Conclusions

To conclude:

• WinCan VX always handles pipe depths in the same way. If it is not specified, then we assume 1m.

  • So, if the cover level is zero, and the pipe depth is null, then the pipe depth is -1m.

• WinCan always considers the object that is being inspected or measured, so in the case of a 3D measurement, it is the pipe that is being measured, so the pipe data takes priority over the node data.

  • If the pipe depth is missing, then we will use the node depth, and in many cases this will give good results for regular manholes, but there can be situations where the results are not what is expected, because this is an assumption.

  • If the pipe and node depth are missing, WinCan assumes 1m.

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