Cоnsider the fоllоwing trаnsportаtion network with two routes between аn origin “O” and a destination “D”. N1 and N2 are the two nodes on the network. t1, t2, t3, and t4 are the link performance functions that give travel times on each link as a function of traffic volume (q1, q2, q3, and q4) on the links. The demand between O and D is 6 vehicle trips per day. Assuming that both routes are used, estimate the traffic flows and total system travel time (i.e., the total travel time of all travelers between O and D) based on user equilibrium principle. The first step is to establish the flow conservation equations: At Node O: [node_O] At Node D: [node_D] At Node N1: [node_N1] At Node N2: [node_N2]