Public transit is free in Paris as world leaders arrive for the global climate change conference.
Subway, train and bus networks in the city will be complimentary until Monday night, CNN reports. The free service started at midday on Sunday, as more than 150 heads of state, including President Barack Obama, gathered for an 11-day climate event.
Authorities made the decision, which CNN said cost an estimated $10 million, after closing several sections of busy highways running from Charles de Gaulle Airport to the northern suburb of Le Bourget, where the event is being held.
They cited security reasons, as many leaders were using those roads to get to the conference. Because of the potential gridlock, regular commuters have been asked to temporarily ditch their cars, while businesses were urged to let staff work from home.
The United Nations climate conference -- known as COP21 -- comes less than three weeks after self-described Islamic State terrorists attacked several locations across the city, leaving 130 dead.
Parisians took to Twitter to praise the free public transit initiative:
Around 300 private security guards and 100 U.N. personnel are guarding the climate event, according to The Local, along with 11,000 uniformed and plainclothes cops.
Leaders want to agree on how to limit emissions below a warming threshold of 2 degrees Celsius (3.6 degrees Fahrenheit), which scientists say could help mitigate some of the worst effects of climate change. The conference runs through Dec. 11.
Paris banned protests ahead of the talks, citing security concerns following the terror attacks. A giant march planned Sunday was replaced with an installation of 10,000 shoes, including pairs belonging to Pope Francis and Vivienne Westwood, in the Place de la Republique.
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