Public transport in Greece will grind to a halt on Tuesday for the second time in less than a week following calls from Greek union leaders for a strong May Day turnout against government plans for pension changes. Public transport workers have scheduled stoppages throughout the day. Flights and shipping will also be seriously disrupted. A mass walkout last Thursday crippled much of the country, despite a last minute decision by the government to freeze its controversial pension reform plans. The Panhellenic Seamen's Organization said its members would strike from 6 a.m. until midnight, keeping all ships in port. Two routes between northern Greece and northeast Greece and two between the main port city of Piraeus and Kalamata, at the tip of the Peloponnese peninsula, will also run.