Vuchic (2005) characterizes two planning approaches to the design of public
transportation networks, which address interchange differently. The integrated (or
overlapping) transit line approach avoids the need for passengers to interchange by creating as
many direct bus or rail services as possible. This approach is illustrated conceptually in Figure
1-1 (reproduced from Vuchic (2005)) which shows that 15 lines are needed to connect all 30
origin-destination pairs for the 6 destinations, but that passengers using such a system would
never have to interchange. On the other hand, the independent transit line approach, also
illustrated in Figure 1-1, connects all 6 destinations using only 3 transit lines if passengers are
willing to interchange once. The inconvenience of interchanging may be mitigated by more
resources being available to invest in higher frequency service on the 3 lines as opposed to
running the 15 lines in the integrated operation