# Intersection Sight Distance

Written by Jerry Ratzlaff on . Posted in Civil Engineering

Intersection sight distance, abbreviated as ISD, is the corner sight distance available in intersection quadrants that allows a driver approaching an intersection to observe the actions of vehicles on the crossing leg.

## Intersection Sight Distance formula

 $$\large{ ISD = 1.47 \; V_{major} \; t_g }$$

### Where:

$$\large{ ISD }$$ = intersection sight distance

$$\large{ V_{major} }$$ = design speed for major road

$$\large{ t_g }$$ = gap acceptance time for entering the major road