There are two alternative routes $1$ and $2($Fig$.8\mathrm{.}36).$ Route $1$ begins from node $r,$ goes through intersection $1,$ and terminates at node $s.$ Route $2$ also begins from node $r,$ proceeds through intersection $2,$ and ends at node $s.$ The total number of trips that should be performed between node $r$ and node $s$ is known, and equal to $2000.$ The route performance functions equal:

$T_1(x_1)=30+0\mathrm{.}03x_1$

$T_2(x_2)=25+0\mathrm{.}04x_2$

where $x_1,x_2$ is the number of trips along routes $1$ and $2.$

Assign flows to routes $1$ and $2$ in such a way to make minimal total travel time of all traffic network users.