By 1820, wrought - iron rails in 20 - foot [6 m] lengths supported the bigger and heavier steam locomotives that were being developed.
Ap 1820. gadu jau tika izmantotas 6 metrus garas kaļamās dzelzs sliedes, kas spēja izturēt jauno, lielāko un smagāko tvaika lokomotīvju svaru.