Thousands of women took advantage of a Swiss Federal Railways offer to ride the country's trains for free on Mother's Day.
Railway authorities said several hundred thousand women had taken advantage of the opportunity to travel by train anywhere in Switzerland without having to pay for tickets.
Extra carriages were put on some trains to cope with the increased demand and many trains were reported to be running at full capacity.
Authorities said the number of people using the federal railway on Sunday was comparable to that of a normal weekday rush hour.
Trains servicing the sites where the country's national exhibition, Expo.02, is due to open later this week were reported to be particularly full.
The offer of free second-class rail travel, extended by the Swiss Federal Railways to all women over the age of 16, was made as part of the company's 2002 centenary celebrations.
"This is [our] centenary," Danni Härry, Swiss Federal Railways spokesman, told swissinfo.
"That means a century of movement, and this is one of the special events we are organising for this birthday," he added.
Men - unaccompanied or otherwise - had to buy tickets as usual to ride the trains on Sunday, but railway officials say their chance may come another day.
"The event is not to be taken too seriously - so this time, yes, women [can travel] for free, but maybe next time we'll have a special offer for men," Härry says.
swissinfo with agencies