Trains is a subtheme of Bulk Bricks introduced in 2000 and currently consists of 5 sets. All sets were released in 2000. As of today, the average annual growth of sets in Bulk Bricks Trains is approximately 3.9% per year.
The LEGO Trains Bulk Bricks theme provided the opportunity to purchase larger quantities of specific LEGO train elements such as doors and windows. Rather than being traditional sets with a diverse array of pieces and instructions to build a predetermined model, Bulk Bricks sets consisted of bags or boxes filled with a single type of brick or a particular element, like doors or wheels. This theme was designed for those who wanted to obtain large quantities of particular pieces without having to buy multiple sets or source them individually.