-City Block
Trains running in city streets can be no longer than the length of a city block; otherwise, they would obstruct traffic every time they stop. A typical light rail car is a little more than 90 feet long.
-Platform
Heavy rail lines can run trains as long as the platforms at each station. Longer trains mean more capacity.
The effectiveness of new rail transit systems when autos and buses are potentially faster, far more convenient, and most important, far less expensive than rails. ….. In response, rail advocates often claim that special circumstances require high capacity trains that can move