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T.P.D.M.V.2.2
2.4.3 Peak Hourly Flows/Design Flow Ratios P/Df
2.4.3.1 Comparison of predicted flows to design flows may be useful in analyzing a network. Such
comparisons should however always be related to hourly flows as daily flows can be extremely
misleading due to the variability of peaking characteristics.
2.4.3.2 Table 2.4.3.1 indicates the implications of various Peak Hourly Flows/Design Flow ratios, P/Df.
2.4.3.3 With regard to existing roads care should be exercised in interpreting P/Df ratios as many
lengths of existing road are constrained by the capacity of existing junctions, and lack of
stopping restrictions. Whilst from Table 2.4.3.1 a P/Df ratio of 0.7 might infer adequate
operating conditions, junctions both within and at the end of the road link may be such that the
flow could never be achieved in practice, and the link would be severely congested well before
a P/Df ratio of 0.7 is reached.