Question $1$: Traffic Volume Analysis $(10$marks$)$

a$.$ Define the term "Design Traffic Volume" and explain its importance in road design.

b$.$ Given the following traffic count data, calculate the Average Daily Traffic $($ADT$)$ and the Peak Hour Volume $($PHV$)$ for a roadsegment:

Monday to Friday traffic counts: $10,000$ vehicles per day

Saturday and Sunday traffic counts: $15,000$ vehicles per day

Peak hour traffic volume on weekdays: $900$ vehicles

Use the ADT to classify the road according to the following categories:

Local road: ADT vehicles$/$day

Collector road: ADT $2,000-10,000$ vehicles$/$day

Arterial road: ADT$>10,000$ vehicles$/$day