Enter the design speed (mph) and the grade (%) into the Stopping Sight Distance Calculator. The calculator will evaluate and display the Stopping Sight Distance.

## Stopping Sight Distance Formula

The following formula is used to calculate the Stopping Sight Distance.

SSD = 1.47*V*2.5+ (V^2/(30*(.34782+(G/100))))

• Where SSD is the Stopping Sight Distance (ft)
• V is the design speed (mph)
• G is the grade (%)

## How to Calculate Stopping Sight Distance?

The following example problems outline how to calculate Stopping Sight Distance.

Example Problem #1:

1. First, determine the design speed (mph).
• The design speed (mph) is given as: 50.
2. Next, determine the grade (%).
• The grade (%) is provided as: 15.
3. Finally, calculate the Stopping Sight Distance using the equation above:

SSD = 1.47*V*2.5+ (V^2/(30*(.34782+(G/100))))

The values given above are inserted into the equation below and the solution is calculated:

SSD = 1.47*50*2.5+ (50^2/(30*(.34782+(15/100)))) = 351.15 (ft)

Example Problem #2:

For this problem, the variables needed are provided below:

design speed (mph) = 709

grade (%) = 5

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer.

SSD = 1.47*V*2.5+ (V^2/(30*(.34782+(G/100)))) = ?