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:
Units | English | Metric |
\(\large{ ISD }\) = intersection sight distance | \(\large{ft}\) | \(\large{m}\) |
\(\large{ V_{major} }\) = design speed for major road | \(\large{\frac{ft}{sec}}\) | \(\large{\frac{m}{sec}}\) |
\(\large{ t_g }\) = gap acceptance time for entering the major road | \(\large{sec}\) | \(\large{s}\) |