Enter the design speed (mph) and the grade (%) into the Stopping Sight Distance Calculator. The calculator will evaluate and display the Stopping Sight Distance.
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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:
- First, determine the design speed (mph).
- The design speed (mph) is given as: 50.
- Next, determine the grade (%).
- The grade (%) is provided as: 15.
- 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)))) = ?
