# Initial Maneuver Distance

Written by Jerry Ratzlaff on . Posted in Civil Engineering Initial maneuver distance, abbreviated as $$d_1$$, is the distance traversed during the perception and reaction time and during the initial acceleration to the point of encroachment on the left lane.

## Initial Maneuver Distance formulas

 $$\large{ d_1 = \frac{ t_1 }{ 0.68 } \; \left( \bar {u} \;-\; m \;+\; \frac{ \bar {a} \; t_1 }{ 2 } \right) }$$ $$\large{ d_1 = 1.47 \; t_1 \; \left( \bar {u} \;-\; m \;+\; \frac{ \bar {a} \; t_1 }{ 2 } \right) }$$

### Where:

 Units English Metric $$\large{ d_1 }$$ = initial maneuver distance $$\large{ft}$$ $$\large{m}$$ $$\large{ \bar {a} }$$ = average acceleration $$\large{\frac{ft}{sec^2}}$$ $$\large{\frac{m}{s^2}}$$ $$\large{ \bar {u} }$$ = average speed of passing vehicle $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$\large{ m }$$ = difference in speed of passing vehicle and passing vehicle $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$\large{ t_1 }$$ = time of initial maneuver $$\large{sec}$$ $$\large{s}$$ 