Rail workers are heading from Glasgow to London calling for renationalisation of the railways.
A series of events in 14 cities will culminate in a rally in London on Saturday 30 April 2005.
The aim to put pressure on the political parties in the run-up to the election.
Rail Maritime and Transport union general secretary Bob Crow said: "Public ownership of the railways will provide a better deal for travellers."
He added: "Public ownership will allow proper transport planning to cope with increased demand for travel due to new developments and the need to reduce road traffic to get cleaner air."
The march began on 23 April in St Enoch Square, Glasgow, where speakers, including Bob Crow and the general secretary of the Scottish TUC, Bill Speirs, addressed the crowd.
They set off towards London in orange and yellow high-visibility clothing as worn by staff on the railways.
When the protest was announced in March the Department for Transport said bringing the railways back under public control was too expensive.
Liberal Democrats say they will have fewer, larger rail franchises with longer contracts.
The Conservatives say they will free "rail and bus companies to invest and innovate."
Information from BBC News.