The term "railroaded" in the sense of having something forced through, either unjustly or without proper regard for those affected, clearly has it's origins in analogy to the way early railroads were build, often running straight through private lands and geographic features.
But the sources I've found seem to all refer to this meaning as having a North American origin, which seems odd, since it is Britain that first experienced this practice, with dead-straight lines cutting ancient estates in two, or dramatically cleaving geographic features (a practice that was rare — and rarely directly experienced in populated areas — in the Americas).
Did "railroaded" originate first in North America or in Britain?
Best Answer
The Oxford English Dictionary quotes early uses of the term rail-road in Britain, for example:
1775 Smeaton Rep. (1837) II. 411 'It seems perfectly practicable to carry the coals upon a rail-road.'
Many other early uses in Britain are cited, suggesting the term was as familiar there as it was later in the United States. Note that the very early British sense included tracks for wheeled trolleys in mines, pushed by men or pulled by pit ponies. But turning to the sense of the word as posed in the original question, it is interesting to consider the OED's definiton of Railroad (verb):
2.b. U.S. To accomplish (an action) with great speed; to 'rush' (a person or thing) to or into a place, through a process etc. 1884 American Law Review in Law Times LXXVII. 104/2 The way men are railroaded to the gallows in that country.
There is, however, an earlier reference (still in the OED) to the British use of the term Railroad to suggest a rushed process:
1840 Thackery Catherine i. Hope, glory,.. and such subjects,.. whirled through their brains at a railroad pace.
What comes out of this is the implication that the early use of the term railroad and railroaded suggests primarily a 'rushed process'. That this implies, or actually involves, overturning convention and opposition arguably follows as much from the rushed nature, as from the practice followed in some (but not all) cases where private lands were resumed or alienated by railroad barons pushing through tracks against the opposition of their former owners. One shouldn't forget that the speed of vehicles on railroads compared to other means of transport must have seemed astonishing to early witnesses of this new technology.
As I understand it, this interpretation might be at odds with Robert Hendrickson's 'The Facts on File Encyclopedia of Word and Phrase Origins (Writers Reference) 2008' which apparently holds that this is a 'common misconception'. I don't have the benefit of Hendrickson's argument for his point of view.