The Trajanic canal at Portus

The hexagonal basin of the Trajanic harbour was connected to the Tiber by a new canal, c. 40m wide, which joined the "Fossa Traiana" near the Episcopio and continued in a north-easterly direction to intersect with the Tiber c. 600m to the north of the "Fossa Traiana". This new canal enabled cargoes that were unloaded in the in the Port of Trajan (Porto di Traiano) to be transhipped from within the hexagon on to barges and moved towards the Tiber, and thence to Rome. All of these arrangements ensured that the whole process of transhipping cargoes and shipping them up-river to Rome would have been much more efficient in the Trajanic port than it had been earlier, a reflection of the increasing importance of Portus in supplying the city of Rome from the earlier 2nd century AD onwards.

The construction of the new Trajanic canal was central to the re-planning of the flat land lying between Portus and the Tiber. The geophysical survey has clearly revealed that a major road ran along the north side of the hexagon to the Tiber. It seems likely that this was a re-routing of the earlier Via Campana on a more direct route to Portus. Similarly, the earlier aqueduct was also re-routed to turn sharply westwards prior to the road, and then to run parallel to it in the direction of the hexagonal basin. The overall effect of canal, road and aqueduct running between the Tiber and the Port of Trajan (Porto di Traiano) must have been very dramatic to visitors approaching the port from Rome, and would have been an eloquent symbol of the imperial power represented by the port as a whole.

The site of the pre-Trajanic river port was also considerably re-developed from the Trajanic period onwards, with the appearance of a major complex of buildings close to where the road reaches the Tiber. Some of these appear to be temples within enclosures, adjacent to later mausolea. Other buildings are harder to interpret, but included warehouses.