i’ve always wondered this
lightrail, streetcars, trams. Why must they be built to be incompatible with heavy rail? why can’t heavy rail be built with a bunch of level crossings, street level stations, slow speeds, and function exactly the same as light rail?
if compatible, the rail could act heavy at designated tracks and light at others, removing what would otherwise be an interchange. it would also allow the light rail to have a higher top speed at express areas.
what am i missing?


Tram-trains are a thing that exists in various places in the world, so it isn’t impossible.
But heavy rail usually has higher platforms, bigger trains, wider wheels than light rail. So there are some challenges, such as:
i hadn’t considered platform height of heavy rail as a limitation!
i;ve seen plenty of old heavy rail lines stopping every 500m, having many curves, yet never having a street level platform.