A railroad tie (1) is manufactured from at least plastic (2), wherein an elongated reinforcing structure (3) is embedded in the plastic. The reinforcing structure in the longitudinal tie direction (L) is extending at least from and including at least a part of one (15) of the two rail supporting longitudinal tie segments up to and including at least a part of the other (16) of the two rail supporting longitudinal tie segments of the railroad tie. In the two rail supporting longitudinal tie segments the railroad tie has a lower lateral stiffness than in an intermediate longitudinal tie segment (17), lying in-between the two rail supporting longitudinal tie segments, which lower lateral stiffness is realized at least by change of shape of the elongated reinforcing structure in the longitudinal tie direction and/or by the range within which said reinforcing structure extends in the longitudinal tie direction.

A composite railway sleeper (1; 50; 100) comprising an outer coating shell (2; 51; 101) made of composite plastic material and a shaped structural core (3; 52; 102), made of a material comprising at least concrete contained within said outer coating shell (2; 51; 510; 101), wherein said outer coating shell (2; 51; 510; 101) presents in the upper outer face (2a; 51a; 101a) two distinct and opposite groups of grooves (4; 53) suitable to receive the angular guide plates (G) belonging to pre-assembled elastic type fastening systems (64) for the connection of two respective rails (R) with said railway sleeper (1; 50; 100).