By Zubair Ahmed
BBC News, Mumbai
Commuters in the Indian city of Mumbai (Bombay) face four days of travel chaos as 450 trains are cancelled while flood-damaged rail lines are repaired.
Mumbai was deluged with monsoon floods last year
The repairs are an attempt to prevent tracks being flooded or swept away during this year's monsoon rains.
Railway authorities are trying to raise tracks above flood-prone areas, after large sections were washed away during 2005's rainy season.
Special buses will run to try to help commuters, railway officials said.
The Meteorological Department has predicted 13 high-tide days during this year's monsoon period.
During one such high-tide on 26 July last year, a massive cloud burst over Mumbai, leading to a record 94cm (3ft) of rainfall.
Almost two-thirds of the city, which is India's financial capital, was covered by floodwaters and more than 1,000 people died.