To calculate the *relative flow synergy *between a pair of schemes, divide the absolute flow synergy for the pair of schemes by the total flow that passes through one of the schemes. Note that the relative flow synergy is not symmetric.

In the example network we are analysing, the relative flow synergy is 23% and 15% for Scheme 1 and Scheme 2 respectively.

The *absolute* *flow alternative* between Scheme 1 and Scheme 2 is the sum of the of trips in scheme 2 where there are trips from same OD pair in Scheme 1.

Where is the number of trips from origin *O *to destination *D *that goes through scheme *i.*

This records both the trips split between parallel schemes as well as those in consecutive schemes (schemes in synergy). Therefore, to separate the flow alternatives from the flow synergies, you must subtract the absolute synergy flow.

To perform this analysis, we use the trip skim matrices produced with the link analysis.