 The only information required to calculate the flows leaving the two branch roadways are the capacities of the two branch roadways and the exiting capacity, the demands into the system, and a value describing how the two input flows interact.This latter input term is called the split priority, or merge ratio, and is defined as the proportion of the two input flows when both are operating in congested conditions.The history of the merge model has its origins in Gordon Newell's description of the merging process, but Daganzo's cell transmission model  lays out a diagram for a highway merge, and describes the application of the theory.