This excerpt was taken from the1995 Canadian Capacity Guide for Signalized Intersections, Second Edition, published by the Institute for Transportation Engineers (District 7 - Canada), (p. 58).
Green Intervals by Balancing Flow Ratios
This procedure uses flow ratios for the critical lanes. First, the total time available in the cycle for the allocation of green intervals is determined as:Sgj = c - S Ij
This total available green time is allocated in proportion to the flow ratio of the critical lane for the corresponding phase and the intersection flow ratio:gj = S gj (yj / Y)
(Explanation for selected cycle time)
The Canadians list several different methods for calculating the total cycle time. The engineer is supposed to select the method that suits his/her purposes best.