TOPL focuses on operations in freeway corridors - road networks comprised of freeways and surrounding arterials. A corridor
is the smallest spatial unit that can be consistently analyzed as a self-contained system. Suppose, for example, that we wish
to consider the impact of a promising new metering algorithm on some ramps on a given freeway. Evidently, this impact will
depend on how other ramps on this freeway are metered. Furthermore, the impact of metering will affect (and be affected by)
the signaling strategies on adjacent arterials. Thus, a good design of the metering algorithms and its proper assessment must
take the entire freeway corridor into account.
On the other hand, a major capacity expansion of a given freeway, such as the addition of a lane or the extension of
the HOV facility, will significantly alter trip patterns. That is, the capacity expansion will have network-wide impact, which
cannot be reliably assessed by studying the freeway alone.
Thus, for the traffic control, incident management, traveler information systems and demand management that TOPL seeks
to assess, a corridor is the appropriate unit of analysis. It may be useful to view TOPL as tools for planning corridor
management.
