By Peter Griffiths
Residents in 23 towns and cities will be able to check how noisy their area is by visiting a new government website, www.defra.gov.uk/noisemapping.
The site collapsed on Friday morning due to "unprecedented demand". A message said engineers were working on the problem.
Ministers say the maps represent the most thorough attempt yet to grasp the scale of a problem that some studies have linked to serious illness and educational difficulties.
The maps, drawn up to meet a European Union directive, will be used to help cut noise in the worst-affected areas.
"They will provide a springboard to go forward and tackle unnecessary and unreasonable noise pollution," said Environment Minister Jonathan Shaw.
"We will use them to draw up action plans to reduce noise where practical from major roads and railways, as well as from urban areas."
The maps were created using data taken at industrial sites, roads, railways and airports. They cover 50,000 miles of roads and 3,000 miles of railways.
The information was collected by airport operators, the Department for Transport, the Highways Agency, Network Rail and the Environment Agency.
London, Manchester, the West Midlands, Liverpool and Nottingham are among the areas covered by the maps.
Researchers have linked loud noise to illness and educational problems in children.
In February, a European Commission-funded study of people living near airports found that the roar of engines instantly raised blood pressure. High blood pressure can lead to stroke, heart failure, heart attack and kidney failure.
In 2005, a team from Queen Mary's School of Medicine, London, said loud aircraft noise could impair children's ability to read and perform memory tests.
(Editing by Steve Addison and Paul Casciato)