PROY-NOM-013-SCT2/2015, "Para durmientes de concreto, Parte 1: durmiente monolítico"
(Draft Mexican Official Standard PROY-NOM-013-SCT2/2015: Concrete railway sleepers - Part 1: Monolithic railway sleepers) (21 pages, in Spanish)

In order to support and guide rolling stock, the track structure must withstand lateral, vertical and longitudinal forces at the same time. As part of the track structure, the sleepers, along with the fasteners, receive the load from the rails and distribute it to the ballast and the underlying subgrade (under SCT standards, the subgrade is the top layer of earth) . The characteristics of the other components of the track structure will therefore affect the design of the sleepers. If concrete sleepers are used, the track's different operating conditions must be taken into consideration. If they are properly designed and their components are correctly connected, installed and maintained, railways tracks with concrete sleepers can be of a higher quality.