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Today there is no commonly accepted standard defining the reference point for calculating the offsets. 

GTS uses the start of the arterial red time as a reference point. At that, the offset in the i-th intersection is equal to the smallest non-negative difference between the start of the i-th red light and that in the i-1-th intersection. It can be easily replaced with any of reference points used by major controllers types such as NEMA TS1, NEMA TS2 or the Type 170. By definition, the offset in the 1-st intersection is 0.

Offset definition on the time-space diagram

Phase sequences ("orders")

Instead of Lead/Lag, Lag/Lead, etc. the following notation is used for brevity. An order is denoted by two digits, the first of them refers to the outbound left turn while the second to the inbound left turn. "1" means that the left turn is leading, "2" - lagging, "0" - there is no left turn.



Types of phase sequences
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