For the intersection of Problem $20-5,$ consider a case in which the E$-$W arterial has two lanes in each direction and the N$-$S arterial has only one lane in each direction. For this case:

a$.$ What is the absolute minimum cycle length that could be used?

b$.$ What cycle length would be required to provide for a ratio of $0\mathrm{.}90$ during the worst $15$ minutes of the hour if the PHF is $0\mathrm{.}92$

EW: $1400$ veh$/$h

NS: $800$ beh$/$h