# Relative Change In Vertical Deviation

Published: August 30, 2018 | Last updated: July 5, 2023

## What Does Relative Change In Vertical Deviation Mean?

In horizontal or vertical directional boring, the relative change in vertical direction (RCVD) is used to provide insight into how a particular drill path is changing relative to its planned trajectory. Although the RCVD value is not as intuitive as the actual vertical deviation measurement, it provides essential predictive qualities which help to assess the performance of the actual drill path.

## Trenchlesspedia Explains Relative Change In Vertical Deviation

The relative change in vertical direction is an important measurement parameter that helps operators to determine what adjustments need to be made to the actual drill path so that it approaches the planned path. The higher the RCVD value, the farther away the actual path is from the intended path, and thus, the greater the adjustments that need to be made.

The RCVD may be determined by the following formula:

RCVD = 1000 × msVDn – msVDn-1 ÷ ΔLn

Where:

msVDn = The vertical distance between the planned path and the actual path at the current station location

msVDn-1 = The vertical distance between the planned path and the actual path at the previous station location

ΔLn = The horizontal distance between the current and previous stations