Difference Between Grades and Elevations

Elevations

Elevation refers to the height of a point relative to a specific reference surface (usually the geoid or mean sea level).

Measurement: Measured using surveying instruments, GPS, or leveling techniques.
Purpose: Gives the vertical position of a point, important for land surveys, topographic maps, and determining the height of buildings, roads, or natural features.
Example: The elevation of a specific location could be 100 meters above sea level.

Grades

Grade refers to the slope or steepness of a surface or a line, often expressed as a percentage. It measures the vertical rise over horizontal distance.

Measurement: Calculated by dividing the change in elevation (vertical difference) by the horizontal distance (horizontal run), and multiplying by 100 to get the percentage.
Purpose: Essential for designing roads, railways, ramps, and drainage systems to ensure proper slope for drainage, safety, and accessibility.
Formula:
Grade (%) = (Vertical Rise / Horizontal Distance) × 100

Key Differences

Vertical vs. Slope: Elevation is a vertical measurement (height), while grade is a measurement of slope (steepness of a surface).
Purpose: Elevation is used to determine the actual height of a location or feature, while grade is used to design surfaces with specific slopes or gradients.
Units: Elevation is in distance units (meters, feet), while grade is usually a percentage or ratio (e.g., 5%).

Example:

Imagine you're designing a road:

The elevation at the start of the road is 100 meters above sea level.
After traveling a certain distance along the road, the elevation increases to 120 meters.
The grade of the road would be calculated based on how much it rises over the distance traveled.