In article , Clive D. W. Feather
writes
The main reason for choosing trams over trolleybuses for any given
scheme is capacity. My vague memory is that the Cross-London route would
require 40tph or 130tbph to provide the same capacity; presumably the
same applies on the Uxbridge Road.

That implies that a trolley-bus can carry only 30% of a tram's
passengers. Why not bigger trolley-buses, maybe bendy ones?
--
Thoss