From India to Japan, railroads mean awesome engineering in extreme environments. From high-tech to home-made, the highest to the fastest, we get on board, in the driver's cab, and even on the roof, to bring you the 10 most extreme railroads on earth. A track in the Colombian port town of Santa Marta has become infamous. Teenagers lie down on the tracks & let the trains run right over them, with only inches between them and the train. We show you the extraordinary footage of this dangerous and illegal game, and how it has alarmingly spread to copycats around the world. In Peru we descend from the Andes on one of the world's highest and steepest railroads. The brake operator risks his life daily as he finds the balance between keeping control and not burning the brakes. The men transport valuable goods from one of the highest mines in the world, to earn a living for their families. Grand Central station is the largest railway station in the world. But under its 44 platforms lies a surprising secret. Danny Brucker takes us underground to visit Track 61, a hidden track going in and out of New York City, used by no less a VIP than Franklin D. Roosevelt. In Thailand, we see a bizarre railroad that cuts straight through a market. Eight times a day the commuter train passes within inches of market stalls - and the stalls part like the red sea. In the train's wake the umbrellas are put back up, the stalls pulled out again, and it's back to business. In a country with the most crowded trains on earth, we travel to the suburbs of Delhi to see commuters pile into trains to get to work on time. We follow Kavita as she pushes her way into one of the new women-only carriages. But there is no room there for Ramesh and Kumar, and they have a different idea. They climb on top of the train, joining dozens of others in the world's most extreme commute. The Bernina line is a breath-taking panoramic railway, in the highest mountain range in Europe. But there is snow on the ground all year round, and it causes numerous problems. We board an extreme machine - the Yellow Beast snowplough, the new weapon in the battle against snow covered railway tracks. This monster machine and its huge blades keep this track clear year round. In Manila we see the ultimate in homemade trains. On the roads millions of cars stuck bumper to bumper. The buses and taxis are at a standstill and the trains are expensive. Homemade trains of just a few planks of wood nailed together are cheap, simple and portable. But when a train on its way they must lift their taxi off the tracks and make sure they do it before the train storms past. Tokyo, the world's biggest city, is home to the world's busiest train stations. Trains come every three seconds but they are packed full, so men called The Oshiya are employed to actually push people onto trains. It's some extraordinary footage. Japanese railroad efficiency reaches its logical conclusion on a test track in Yamanashi, where the Maglev train became the fastest in the world - at three hundred and sixty one miles per hour. At number two is the world's most exposed railway. The Pamban Rail Bridge in Southern India, battered by waves and cyclones on this stormy coastline. But standing between the Pamban bridge and destruction are the maintenance team. We follow them as they avoid oncoming trains to keep the track safe from rust, and we speak to local villagers about the terrible day in 1965 when the village, and the old bridge, was almost completely destroyed by a cyclone. Finally, at number one, surely the most dangerous railroad on earth. For some of the youth in Soweto, Johannesburg, with little hope of a job and drug addiction rife, they find other ways to make their mark. Using the speeding train as their stage, Soweto teenagers perform ever more daring stunts. The most death-defying of all is train surfing: performing acrobatics on the top of moving trains, while dodging cables carrying three thousand volts of electricity.