Intersection Sight Distance

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