Determine an appropriate yellow interval for a signal phase under the following

conditions:

$$ Approach speed limit: $40$ mi$/$hr

$$ Perception$-$reaction time: $1\mathrm{.}5$ sec

$$ Deceleration rate: $11\mathrm{.}2$ ft$/$s $2$

$$ Vehicle length: $20$ ft

$$ Width of intersection $($to be traversed$)$: $60$ ft$.$

$$ Assume no grade.

If there$$s no all red clearance phase, what should the yellow interval $($Y$)$ length be$?$

If there$$s an all red clearance phase, what should the yellow interval $($Y$)$ and all red

interval $($AR$)$ be$?$