$1\mathrm{.}2$ Briefly explain the difference between pre$-$timed and demand$-$actuated traffic signals.

$1\mathrm{.}3$ The sketch below shows design data for a three phase, pre$-$timed signal of an atgrade intersection. Assume total lost time per phase equals to $3sec,$ yellow time $=3$ sec per phase, clearance time $=2sec$ per phase. Ignore pedestrians.

$1\mathrm{.}3\mathrm{.}1$ Use Webster's equation to estimate the optimal cycle length $($Round up to the nearest $10).$

$(11)$