Set Elevations System Analysis

The Set Elevations tool uses a hierarchy in determining the best and most accurate elevation data for each pipe segment. This process is defined below:

1. Field Information: First, the program checks gathered field information to populate the Rim Elevation and Invert Elevation fields:
   • Rim Elevation: In Structure Inventory, the program locates Rim Elevation data stored on the Attributes tab. If the Rim Elevation has a Rim Status of "Field Verified", this data is placed in all the appropriate Rim Elevation fields in the Pipe Inventory module.
   • Invert Elevation: In Lamping Inspections, the program locates the Rim to Invert measurement on the General tab. If this data can be located or if there is a Structure Depth value in Structure Inventory (on the Attributes tab), then the invert is calculated by taking the rim elevation minus the depth of the structure (Invert = Rim Elevation - Structure Depth). This data is then placed in all appropriate Invert Elevation fields in the Pipe Inventory module.

     When the Rim Elevations and Invert Elevations are populated using this method, the Rim Status and Invert Status is set to "F" for "Field Verified".

2. Record Drawing Data: If the above "Field Verified" data cannot be found, the system will then search for record drawing data. If the Pipe Inventory records have elevations in the Record Drawing Rim and/or Invert Elevation fields, then this data is copied into the Active Elevation fields.

   When the Rim Elevations and Invert Elevations are populated using this method, the Rim Status and Invert Status is set to "R" for "Record Drawing".

3. Calculated Data: Next, the system will use calculated data. If a datum adjustment figure exists in Pipe Inventory on the Elevations tab (i.e. Adj US Rim Elev, Adj US Inv Elev, etc.), then it is added to the Record Drawing Elevation. This value is then placed in the appropriate Active Elevation fields.

   When the Rim Elevations and Invert Elevations are populated using this method, the Rim Status and Invert Status is set to "C" for "Calculated".

4. Combination of Field Verified Data and Record Drawing Data: Elevations are calculated using the four following scenarios (depending on which criteria is met):
   • If a structure has a Record Drawing Rim Elevation and a Rim-to-Invert measurement in Lamping Inspections, but does not have a "Field Verified" Rim Elevation in the Structure Inventory module, then the invert is calculated by taking the Record Drawing Rim Elevation (plus the datum adjustment if one exists) and subtracting the Rim-to-Invert measurement. This is summarized below:

   Record Drawing Rim Elevation Exists	Yes
   Rim-to-Invert Measurement Exists	Yes
   Rim Elevation is Field Verified	No

   Invert = (Record Drawing Rim Elevation + Datum Adjustment) - Rim-to-Invert

   When the Rim Elevations and Invert Elevations are populated using this method, the Rim Status is set to "R" for "Record Drawing" or "C" for "Calculated" and the Invert Status is set to "L" for "Lamping".

   • If a structure has a Record Drawing Rim Elevation in Lamping Inspections and a Structure Depth in Structure Inventory, but does not have a Rim-to-Invert Measurement in Lamping Inspections or a "Field Verified" Rim Elevation in Structure Inventory, then the invert is calculated by taking the Record Drawing Rim Elevation (plus the datum adjustment if one exists) and subtracting the structure depth. This is summarized below:

   Record Drawing Rim Elevation Exists	Yes
   Rim-to-Invert Measurement Exists	No
   Rim Elevation is Field Verified	No
   Structure Depth Exists	Yes

   Invert = (Record Drawing Rim Elevation + Datum Adjustment) - Structure Depth

   When the Rim Elevations and Invert elevations are populated using this method, the Rim Status is set to "R" for "Record Drawing" or "C" for "Calculated" and the Invert Status is set to "D" for "Depth".

   • If a structure has a Record Drawing Invert Elevation and a Rim-to-Invert measurement in Lamping Inspections, but does not have a "Field Verified" Rim Elevation in Structure Inventory, then the invert is calculated by taking the Record Drawing Invert Elevation (plus the datum adjustment if one exists) and adding it to the Rim-to-Invert measurement. This is summarized below:

   Record Drawing Invert Elevation Exists	Yes
   Rim-to-Invert Measurement Exists	Yes
   Rim Elevation is Field Verified	No

   Invert = (Record Drawing Invert Elevation + Datum Adjustment) + Rim-to-Invert Measurement

   When the Rim Elevations and Invert Elevations are populated using this method, the Rim Status is set to "L" for "Lamping" and the Invert Status is set to "R" for "Record Drawing" or "C" for "Calculated".

   • If a structure has a Record Drawing Invert Elevation in Lamping Inspections and a Structure Depth in Structure Inventory, but does not have a Rim-to-Invert Measurement in Lamping Inspections or a "Field Verified" Rim Elevation in Structure Inventory, then the invert is calculated by taking the Record Drawing Invert Elevation (plus the datum adjustment if one exists) and adding it to the Structure Depth. This is summarized below:

   Record Drawing Invert Elevation Exists	Yes
   Rim-to-Invert Measurement Exists	No
   Rim Elevation is Field Verified	No
   Structure Depth Exists	Yes

   Invert = (Record Drawing Elevation + Datum Adjustment) + Structure Depth

   When the Rim Elevations and Invert Elevations are populated using this method, the Rim Status is set to "D" for "Depth" and the Invert Status is set to "R" for "Record Drawing" or "C" for "Calculated".

5. Conflicting Datum: Sometimes, when structure Rim Elevations have not been "Field Verified", a structure can end up with two or more elevations for the rim if various as-built drawings contained conflicting data and the datum adjustment did not equalize the rim elevations. For structures that fit in this category, you can specify for the program to look at all structures where the rim elevations are different. The program then goes through an algorithm and changes one or more of the rim elevations.

   When the program changes a Rim Elevation because of this scenario, the Rim Status is set to "P" for "Program Adjusted".

6. Calculating Inverts Based on the Slope of the Pipe: Inverts are calculated using one of the following two scenarios (depending on which information is present):
   • If a record is missing the Upstream Invert Elevation and the pipe has a Downstream Invert Elevation and a Slope, then the Upstream Invert is calculated by taking the Downstream Invert Elevation plus the Slope of the pipe divided by 100 multiplied by the Length of the pipe.

     Upstream Invert = Downstream Invert Elevation + (Slope/(100*Pipe Length))

   • If a record is missing the Downstream Invert Elevation and the pipe has an Upstream Invert Elevation and a Slope, then the Downstream Invert is calculated by taking the Upstream Invert Elevation and subtracting the Slope of the pipe divided by 100 multiplied by the Length of the pipe.

     Downstream Invert = Upstream Invert Elevation - (Slope/(100*Pipe Length))

     When the Invert Elevation is populated using either of these methods, the Invert Status is set to "S" for "Slope".