Bus : Alghero Airport -Cagliari

A bus leaves from Aghero airport for Cagliari after every Ryanair Arrival, the bus costs about 20 Euro and the journey time is approximately 3 hours….sit back and enjoy the countryside. the bus makes one stop at a service station for refreshments(depending on how the driver feels). This service is operated by Logudoro Tours

You can travel by train OR by bus(Much much quicker!) between Cagliari and Alghero. Suggest that you look up the schedules to determine the better connections 

www.trenitalia.com (train between Cagliari and Sassari)

www.ferroviesardegna.it (bus between Cagliari and Sassari; bus between Sassari and Alghero; train between Sassari and Alghero).

Trains : Alghero-Sassari

The train between Sassari and Alghero won’t take you into the main part of Alghero, but 1.5 kilometers north, at the Alghero Lido, which has several hotels along the beach. If you want to get to the main part of Alghero (including the historic center), take the bus, not the train.

Bus : Cagliari-Sassari
The non-stop bus between Cagliari and Sassari will be faster than the train. It is schedule 343 on the website www.ferroviesardegna.it Sassari to Alghero is schedule 323

Bus & Train Stations in Sardinia

The bus and train stations in Cagliari are 200 yards apart and are located in the center of the town near the port.

The bus and train stations in Sassari are 400 yards apart.

The bus terminus in Alghero is 200 yards from the entrance to the Old Town. The bus drops you within 100 yards from the Hotel Catalunya and 250 yards from the Hotel San Francesco.