deletions | additions       diff --git a/Methodolofy Measurement Definitions.tex b/Methodolofy Measurement Definitions.tex  index 18e61e4..fc0463e 100644  --- a/Methodolofy Measurement Definitions.tex  +++ b/Methodolofy Measurement Definitions.tex 
...
It should be noted that line-of-sight is not needed to estalish a spatial relationship between vehicles, however, it may hold explanatory insight into how interactions form. As such, line-of-sight is not considered in the interaction   \subsubsection{TTC}  \subsubsection{PET} \subsubsection{Time-to-collision}  \subsubsection{Post-encroachment time}  Trajectory data is detailed enough to provide gap acceptance time (GT) and post-encroachment times (PET). These are measures that broadly characterise how aggresively merging and crossing tasks are performed, respectively. As such, there is generally only one of these measures for the entire common time interval of a pair of road users.  For the crossing zone defined by the intersection of the two trajectories of a pair of road users, the post-ecnrochment time measure the time between complete departure of the first arriving vehicle, and first arrival of the last arriving vehicle. If PET < 0, a collision ensues. As such, higher PETs demonstrate safer behaviour.  Gap acceptance time similarly measures arrival and departure of a road user at a common crossing zone, but in this case, the crossing zone occurs inline during a merging task, usually followed by following behaviour.