This was posted on the Evening News website:
“A trolleybus is different from a normal bus: it runs on electricity from overhead wires (all or most of the time). This makes it (a) more efficient (around twice as efficient as a diesel bus) and (b) clean: no harmful emissions are released in our streets”.
This is very true. Trolley buses are a good solution in many situations.
BUT running on electricity does not exempt them from getting stuck in traffic and all the other myriad disadvantages of driving through a congested city centre. Because of this, they cannot realistically be timetabled as efficiently as a tramway with traffic light sequences etc married to their progress to ensure that they are not snared in traffic.
They are still prone to the “you wait ages, and then 3 come at once” problem because they too would pile up behind each other at traffic lights etc. And in fact it would be even worse due to the fact that because they are connected to wires, it is harder (though not impossible) for them to overtake each other. The more often this has to happen, the more you lose any benefits due to their being trolley buses, and there is time loss for connecting and reconnecting to the overhead wires every time. Having said that, it need not be the case that this be too dramatic apparently http://www.youtube.com/watch?v=ZpZxvJjpHSs.
(regarding that you tube clip – the trolley bus there in Beijing appears to be a normal bus, it would still get stuck in traffic. So my point still stands: trolley buses only offer a solution in Edinburgh where they are physically segregated. In which case you may as well have trams)