In this handout image provided by the Police of Swiss canton Valais the wreckage of a bus is seen after it crashed inside a motorway tunnel on March 13, 2012 in Sierre, Switzerland. 28 people, including 22 children, returning from a skiing holiday died in this bus accident. (Photo by Police Cantonale Valaisanne via Getty Images)

A British inspired Transformer, made from original bus parts is displayed in front of Tower Bridge on November 28, 2009 in London, England. Twitter fans voted to see a London “bendy” bus made into a Transformer to celebrate the DVD & Blu-ray release of “Transformers: Revenge of The Fallen”. (Photo by Marco Secchi/Getty Images for Paramount Home Entertainment)

Emergency services work at the scene of a bus accident on the Kingsway in central London February 2, 2015. A number 91 double-decker bus had its roof ripped off after hitting a tree, causing injury to passengers and passers-by, local media reported. (Photo by Peter Nicholls/Reuters)

In this photograph taken on May 20, 2014 nine year old Indian boy Lakhan Kale is tied with a cloth rope around his ankle, to a bus-stop pole in Mumbai. The nine-year-old boy dressed in blue lay listlessly on the pavement in the scorching Mumbai summer afternoon, his ankle tethered with rope to a bus stop, unheeded by pedestrians strolling past. Lakhan Kale cannot hear or speak and suffers from cerebral palsy and epilepsy, so his grandmother and carer tied him up to keep him safe while she went to work, selling toys and flower garlands on the city's roadsides. (Photo by Punit Paranjpe/AFP Photo)

Coffins are lined up near the wreckage of the bus, on July 29, 2013. (Photo by Salvatore Laporta/Associated Press)

People try to board a goverment bus during the second day of a suspension of public transport services in Apopa, El Salvador July 28, 2015. Violent gangs in El Salvador ordered bus drivers to strike on Monday in a conflict that has killed six people and left thousands of commuters stranded on the streets of the Central American capital, police and bus company officials said. (Photo by Jose Cabezas/Reuters)

People look through the front windshield of a damaged trolleybus in Donetsk, January 22, 2015. At least seven civilians were killed on Thursday when a shell or a mortar hit a trolleybus stop in the rebel-controlled city of Donetsk in eastern Ukraine, a Reuters witness said. The Reuters cameraman said he saw six bodies on the ground near, and inside, a trolleybus in a southern district of the city. Windows of shops nearby had been blown out by the blast. (Photo by Alexander Ermochenko/Reuters)

In this Tuesday, August 2, 2016 photo released by Xinhua News Agency, people stand on a platform as the Transit Elevated Bus TEB-1 conducting a test run after it unveiled in Qinhuangdao, north China's Hebei Province. The 72-feet long and 25-feet wide Transit Elevated Bus (TEB) powered by electricity can carry more than hundreds passengers, is designed to go over the normal traffic to help ease traffic congestion without having to dig new tunnels or build elevated rail tracks. (Photo by Luo Xiaoguang/Xinhua via AP Photo)