Stopping Sight Distance Calculator

Calculate the minimum distance required for a vehicle to stop safely based on speed and reaction time

Input Parameters

Calculation Results

Stopping Sight Distance (SSD)

-- km --

Calculation Formula

SSD = (0.278 × v × t) + (v² / (254 × f))

Where:
SSD = Stopping Sight Distance (meters)
v = Vehicle speed (km/h)
t = Driver reaction time (seconds)
f = Road friction coefficient

Stopping Sight Distance Calculator Usage Guide

Learn how to use the Stopping Sight Distance Calculator and understand its importance in road safety

What is Stopping Sight Distance?

Stopping Sight Distance (SSD) is the minimum distance required for a vehicle to stop safely under given conditions. It accounts for both the driver's reaction time and the braking distance of the vehicle.

How to Use This Calculator

  1. Enter the vehicle speed in km/h
  2. Set the driver reaction time (default is 1.5 seconds)
  3. Adjust the road friction coefficient (typically between 0.2 and 0.4 for dry roads)
  4. Click "Calculate" to compute the stopping sight distance

Importance in Road Design

SSD is crucial for determining:

  • Horizontal and vertical curves on highways
  • Clear sight triangles at intersections
  • Minimum sight distances at pedestrian crossings
  • Designing adequate sight distances at traffic signals

Example Calculation

If a vehicle is traveling at 60 km/h with a reaction time of 1.5 seconds on a road with a friction coefficient of 0.3, the stopping sight distance would be approximately 78.8 meters.