Traffic signal timing plans are derived from vehicle trajectory or probe data. The probe data is collected and archived in a datastore over a sample time on the order of weeks or longer. Probe data is corrected for clock drift, geo-fence filtered to a selected intersection, and then stop line crossings in the intersection are identified and analyzed along with related data to determine the timing plans and schedule for the intersection. In this way, access to government agency timing plans is obviated so as to save time and expense.