This aerial picture taken on June 6, 2016, shows the scene of a collision between a freight train and a passengers train on their way between Liege and Namur, in Saint-Georges-sur-Meuse, Eastern Belgium. Investigators worked through the wreckage of a high speed train crash in eastern Belgium on Monday that killed at least three people and injured nine others. A fast-moving passenger train late Sunday slammed violently into the back of a slow-moving freight train that was travelling on the same track for reasons that remain unexplained. (Photo by Laurie Dieffembacq/AFP Photo)

A tourist catches snowflakes on her tongue during snow fall in Times Square, Midtown, New York, on January 3, 2013. A major snowstorm producing blizzard-like conditions hammered the northeastern United States on Friday, causing more than 1,000 U.S. flight delays and cancellations, paralyzing road travel, and closing schools and government offices. (Photo by Darren Ornitz/Reuters)

In this Sunday, April 28, 2013 photograph, people watch as Indian Sailendra Nath Roy attempts to cross Teesta river suspended from a zip wire attached to his ponytail moments before his death in Siliguri, West Bengal state, India. Roy who was named a Guinness World Record holder in 2011 for travelling the farthest distance on a zip wire using hair died during the stunt Sunday when he suffered a heart attack. (Photo by AP Photo)

“I was on Durga Puja Festival vacation, travelling on a local train. A boy was singing devotional song and begging for alms. He was guised as a Hindu god, Lord Shiva. This is a common view in Indian trains but this boy was charming, bright and did have a melodious voice. My camera was ready hanging on my neck so I took a picture”. (Photo and caption by Arup Ghosh/2014 Sony World Photography Awards)

A United States Air Force (USAF) F-15 fighter jet travels at low altitude through the “Mach Loop” series of valleys near Dolgellau, north Wales on June 26, 2018. The Mach Loop valleys, situated between Dolgellau and Machynlleth, are regularly used by the military for operational low flying training which can take place as low as 76 metres from the nearest terrain. The USAF regularly use the loop to practice low-altitude flight, which confuses radar systems. (Photo by Oli Scarff/AFP Photo)

Ellen MacRae a student from Edinburgh University take a lateral flow antigen test at a test centre which is also open to students in Edinburgh Napier University, Queen Margaret University and SRUC on December 1, 2020 in Edinburgh, Scotland. The programme is running in partnership between the University of Edinburgh and other Scottish universities, the Scottish Government and NHS Test and Protect, supporting students leaving their term-time accommodation to travel home at the end of term for the winter break. (Photo by Jeff J. Mitchell/Getty Images)

Men wear masks as they sit in the metro in Prague, Czech Republic, 17 March 2020. According to media reports, the Czech government decided to impose a two-week quarantine in the country on the evening of 15 March, and ban all international travel from 16 March 2020. Currently 383 cases of the coronavirus SARS-CoV-2, which causes the Covid-19 disease, have been officially confirmed in Czech Republic. (Photo by Martin Divisek/EPA/EFE)

This aerial photo shows bullet trains parked at a station in preparation for the upcoming Lunar New Year travel peak in Nanjing, in eastern China's Jiangsu province on January 27, 2021, as authorities have encouraged people to stay put during the Spring Festival to curb the spread of of COVID-19 coronavirus. (Photo by AFP Photo/China Stringer Network)