Transportation Geography and Network Science/Topology
Circuits and Trees
Circuits and Trees are two basic structures of planar networks. A circuit is a closed path, with no less than three links, that begins and ends at the same node. A tree is a set of connected lines that cannot form a complete circuit. 
At the individual trip level, the treeness is estimated as:
= Length (km) of street segments belonging to a branch network within the buffer,
= Total length (km) of the street network within the buffer.
- Open source software developed by Feng Xie, Metropolitan Washington Council of Governments (MWCOG) can be used to identify tree and circuit links on planar networks. Code can be downloaded from