sentences:  The build-operate-transfer concession agreement mandated construction, maintenance and management of the route and its upgrade to motorway standards; this requirement included the building of dual carriageways when the annual average daily traffic (AADT) reached 10,000 vehicles per day or when the average summer daily traffic (ASDT) reached 16,000 vehicles per day.The latter was achieved in 2005 and the motorway upgrade started in 2008, even though the AADT at the time was only 8,500 vehicles.The A8 expansion was commenced by the operator, BINA Istra, immediately following a similar expansion of the A9; on the latter, the entire route was widened except for the two largest bridges, for which the expansion was postponed.