from the highway  (A1) you can choose many roads:

 - highway (A30)  to Salerno,  where you get the road S.S. 163 direction  Vietri sul Mare, that it takes you on the Coast of Amalfi.

- highway (A1), direction Napoli, then follow the indication to highway (A3), the choose three possibility:

Gate Castellammare di Stabia,  
where you get the Coast of Amalfi by Sorrento and then following to Positano or direction to  Agerola; it takes directly to  Amalfi

Gate Angri, 
direction to  Valico di Chiunzi. There from the Valico di Chiunzi you can get two roads; on the left to Maiori, while on the right to Ravello.

Gate Vietri sul Mare
follow the S.S. 163 Costiera Amalfitana.

Finally there are  pubblic bus service, offered by “Sita”, that connect the Amalfi coast to the various towns in the province

 web site: www.uniplan.it/sita