Question $4[15$ marks$]$

Identify and briefly describe the two basic demand forecasting situations in transportation planning. $[4$ marks$]$

A small town has been divided into three traffic zones. An origin$-$destination survey was conducted earlier this year and yielded the number of trips between each zone as shown in the table below. Travel times between zones were also determined. Provide a trip distribution calculation using the gravity model for two iterations. Assume $K_{ij},$ the socioeconomic adjustment factor, is the same unit value for all zones. $[11$ marks$]$

The following table shows the number of productions and attractions in each zone.

Table $4\mathrm{.}1$ Trip Production and Attractions for a Three$-$Zone Area

$\backslash$table$[[$Zone$,1,2,3,$Total$],[$Productions$,400,400,100,900],[$Attractions$,300,300,300,900]]$

The survey's results for the zones' travel time in minutes were as follows.

Table $4\mathrm{.}2$ Travel Time between Zones $($min$)$

$\backslash$table$[[$Zone$,1,2,3],[1,5,2,3],[2,2,6,6],[3,3,6,5]]$

Table $4\mathrm{.}3$ Travel Time versus Friction Factor

$\backslash$table$[[$Time $($min$),F$