A classification for conventional, high-capacity rail systems, including standard freight networks, intercity passenger routes, and rapid transit subways. It distinguishes these robust, fully grade-separated operations from streetcars or light rail systems that might share traffic lanes. The term refers to the passenger volume and infrastructure scale, not the physical weight of the steel rails.
The city is debating whether to extend the heavy rail line or just build a light rail loop.
Related terms
Light rail
An urban electric passenger railway operating single cars or short trains, often sharing street space.
Commuter rail
A passenger train service connecting a city center with its surrounding suburbs.
Main line
The principal track or tracks of a railroad between terminals, where trains need authority to run.