Why did Claudius build a new harbor at Ostia?

Emperor Claudius constructed a new artificial harbor at Ostia—which later became known as Portus—primarily to reorganize and secure the grain supply of Rome.1

The existing harbor at Ostia had become inadequate for large vessels because it was partly obstructed by a sandbar, hindering the city's vital maritime commerce. By building this new, larger facility, Claudius aimed to improve the efficiency and reliability of the shipments essential for feeding the capital. The harbor was later connected to Rome via a canal and the Tiber River, further streamlining the transport of goods.213