A train was a grouping of vehicles that moved, particularly over metal rails, transporting passengers or freight.
On Earth
The Fifth Doctor, after landing his TARDIS at a train station in Oxfordshire on 11 June 1925, mentioned to his companions that he had always wanted to drive a train as a boy. (TV: Black Orchid) The same was true of Henry Gordon Jago. (AUDIO: Higson & Quick)
In 1863, the Third Doctor and Charlie Fisher used a train engine to escape from the Confederate lines after their hot air balloon was shot down. (COMIC: Backtime)
In 1868, Ian Chesterton used a train to kill the Animus, which was hiding in the London Underground. (COMIC: Unnatural Selection)
In 1879, Queen Victoria had planned to take the train to Aberdeen, but was forced to go by coach when a fallen tree blocked the line, as arranged by the Brethren. (TV: Tooth and Claw)
In 1885, a Shift Agent took over a steam train in order to get to Euston and recover a case of dark matter. (COMIC: Track Attack)
In 1898, Ian Stratford took the train from Paddington station to the town of Three Sisters. (PROSE: The Banquo Legacy)
In 1909, Jack Harkness and a group of soldiers under his command were travelling through Lahore by train when the soldiers were killed by Fairies. (TV: Small Worlds)
The Eighth Doctor claimed he took a train with Lenin from Switzerland to Petrograd. (AUDIO: Storm Warning)
In 1917, the Doctor's TARDIS materialised on a train en route to Darjeeling, India. (AUDIO: The Roof of the World)
On 1 September 1939, Cecelia Pollard was convinced to board the Vienna to Calais Transcontinental Express by Celestial Intervention Agency agent Torvald instead of committing suicide. President Romana II, Leela, Narvin, Mephistopheles Arkadian and Torvald all boarded the train because of Cecelia's presence. (AUDIO: A Blind Eye)
On 7 September 1952, the Sixth Doctor and Evelyn Smythe visited the train Ivy Lee. (AUDIO: The Nowhere Place)
In 1967, Madeline Burton, while using Om-Tsor, accidentally caused a train in northwestern India to derail, killing the hundreds of people on board. (PROSE: Revolution Man)
In 1979, the Fourth Doctor and Romana II took a train while in Paris. (TV: City of Death)
Circa 1990, the Seventh Doctor and Sarah Jane Smith took a train to Royal Albert Hall, which was abducted by the Kalik. (COMIC: Train-Flight)
In 1993, a Fortean Flicker transported a group of train passengers to Hogsumm. (PROSE: The Highest Science) They were later returned to their own time by Romana II. (PROSE: Happy Endings)
Circa December 2009, Mike Yates took a train to Nest Cottage to answer a strange advertisement. (AUDIO: The Stuff of Nightmares)
In Bristol in the 2010s, a train almost ran over a defenseless and externally shrunken TARDIS, which had the Twelfth Doctor inside. Later, Clara Oswald and Rigsy used another train in an attempt to trample a group of the Boneless. However, the plan failed as the Boneless turned the train two-dimensional. (TV: Flatline)
Miss Quill wondered if Dorothea Ames' metaphysical engine "buzzed [her] atomically" to the Peak District. She pointed out the area's relative proximity to Coal Hill Academy by saying, "There are trains for that." (TV: The Metaphysical Engine, or What Quill Did)
In 2050, due to the Oroborus consuming time, all the trains in London ran on time, even if they were several hours late, and some trains even arrived before they had left. (TV: Oroborus)
In 2080, Ileana de Santos and her associates took a private monorail train from Rio de Janeiro to a ranch house in the Amazon desert. The Fifth Doctor, with some difficulty, materialised the TARDIS in the train's baggage car. (AUDIO: Loups-Garoux)
Alternate timelines
In an alternate timeline, Amy Pond took the Eleventh Doctor aboard a train headed for Area 52 in Egypt. A train also ran through the Gherkin. (TV: The Wedding of River Song)
On other planets
On an Earth-like planet, the Daleks used a train for transport. The Second Doctor crashed the train by removing a section of the track, causing it to derail. (COMIC: The Exterminator)
One human colony world which was mostly ice used skitrains, which had runners instead of wheels. (PROSE: Cold Fusion)
On the stormy planet Tempest, the only way to safely traverse the wastelands was by monorail trains. (PROSE: Tempest)
On Florana, trains were used to transport prisoners to factories. (AUDIO: The Elite)
In a heavily polluted city on an Earth-like world, the Fourth Doctor assisted the Guardian Angels in finding the correct train track which would lead them out of the city and to the countryside. However, when he arrived there in the TARDIS and waited for them, they never arrived, and he concluded that they didn't make it, which was perhaps just as well since the countryside was just as polluted as the city itself. (COMIC: End of the Line)
In the Matrix on Gallifrey, the Fourth Doctor found himself trapped on a recreation of a train line, his foot caught in the tracks after the points changed, while Goth drove a train toward him. The Doctor freed himself and jumped clear at the last second, and the train vanished. (TV: The Deadly Assassin)
On the Dalek Foundation world of Sunlight 349, journalist Lillian Belle was gathering information at the site of a head-on collision between two trains. When a Dalek arrived on the scene, it murdered one of the drivers (Mr Sezman) and the medics who rescued him from the wreckage and left. (PROSE: The Dalek Generation)
Through space
A space-faring version of the Orient Express ferried passengers between planets, travelling along hyperspace ribbons. (TV: Mummy on the Orient Express)
The Eighth Doctor kept a model train set in his TARDIS, which he constructed over a period of several years until it eventually became a microcosm of its own. (PROSE: Model Train Set, Vampire Science, Genocide)