The estimate reflects the Annual Average Daily Traffic (AADT) for that link. One can therefore use a variety of available information to influence the final decision as to what this value should be. This flexibility should always be borne in mind. Essentially, each method to calculate an estimate is effectively only a recommendation and the final decision as to what value to adopt always rests in the end with the Asset Manager.

The estimate should also be tied to a year, being an annual average. There should only be one AADT in anyone year. This is not to say it can’t be changed if better information comes to light. But certainly on a network level, it is recommended that estimates are updated annually. Any more frequent is likely an inefficient use of time. Any less often reduces the currency of the estimate data being used.

It is recommended that only one estimate is allowed in a calendar year as an example. Any estimates should be overwritten each time the update is run, or an estimate is manually updated in the year (calendar or financial). But it is useful to have a history of estimates, as much as counts, to show development over time.

It is noted that some roads do have significant seasonal variations. For example, care should be taken where seal designs for summer traffic volumes are based on estimates from a winter count.

It was noted that the TCE generates significant amounts of estimates as one is created each time the process is run. It is recommended that any process include some measure to distinguish between updating links which have had a count and a full annual update across the network.