Traffic Officer

A traffic officer receives complaints on frequent traffic jams at a traffic signal on the main street of a busy market. He studied the traffic pattern and to simplify calculations made a reasonable assumption that all the vehicles are identical in size and move with identical speeds. At present durations of red & green signals are equal and average speed of traffic advancement is $v_1= 1.5\text{ m/s}$ . For improvement in the situation if he orders to make duration of green signals $n=2$ times and to leave that of red signals unchanged, what would be average speed of $v_2$ of the traffic advancement?