In 1972 LEGO released the 4.5V and 12V train sets as part of the Blue Era which was named because of the rail color. These train sets used additional conductor rails mounted between the standard 4.5V rails and 12V motors contained in the same housings as the 4.5V motors, but with additional metal contacts attached to the bottom of the housings.
1978 LEGO Sets
In 1978, LEGO introduced several groundbreaking themes that would define the company for decades. One of the most significant developments was the expansion of the LEGO Town theme, which built upon previous city-focused sets. This year, LEGO introduced new models of public transportation, including buses and taxis, further enhancing the realism and playability of urban environments.