Arrival Turning Flows
User Guide > Average Daily Traffic
Average Daily Traffic
For accident estimation the 24-hour Annual Average Traffic (AADT) turning flows are needed. This may be available for an existing situation.
For future flows, estimates are often not available or are only AADT arrival flows rather that the required turning flows.
To help in these situations the 24-hour ADDT turns can be synthesized from the AM and PM turning flows.
Typically, 24-hour AADT turns are synthesized by multiplying the (AM turns + PM turns) by a default factor of 5. The default can be edited where appropriate.
If the AADT arrivals flows are known the AADT turns can be synthesized by using the AM + PM turns multiplied by the appropriate factor per leg. This will produce the given flows / leg distributed according to the (AM+PM) turning proportions, which are a good estimate of the 24-hour turning proportions.
It is essential that both the AM peak and the PM peak turning flows are correct (not template values). To ensure this the AM and PM turns are displayed when deriving the 24-hour ADDT turns so they can be checked before proceeding.
It can be seen above that the PM flows are real but the AM peak has template flows with 100 for each turn, so proceeding would produce a spurious estimate of AADT turns until the AM peak is corrected.
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