When I was young there still were some electric buses on the streets of NYC. They got their power from overhead wires and a shoe system on the roof of the bus. There was enough reach that they could swing over to the curb to make stops and still maintain contact.
There were two drawbacks. First, if the shoe came off the driver would have to get out of the bus and do some fancy pushing and pulling with a long rod to get things hooked up again. If things really got snagged the bus could be disabled for an extended period of time.
Second, at busy interchanges there were wires running in all directions with fancy (and unsightly) switching devices to allow the bus to change routes.
They did have two positive aspects. They didn't pollute and they didn't make much noise. With the revived interest in inner city mass transit (especially light rail) it seems to me that electric buses should be reconsidered.
First, the improvement in battery technology (and small auxiliary fossil fuel motors) could allow them to operate over a few miles without overhead power. This means that the interchange switches could be eliminated. The bus would just disconnect at the route change and reconnect after entering the new route. It could also allow them to continue on if they got disengaged and stop at a suitable point to reconnect, or perhaps a better shoe system would reconnect automatically after the bus had moved on some distance.
Second, it would be much easier and cheaper to start such a service compared to light rail. There is no need for laying track nor for a special right of way, although a dedicated bus lane could be established if desired. All that is required is to string some power cables along the new route and perhaps some special traffic signals.
I can't be the first to think of this, so if it is being done why haven't we heard more about it, and if it isn't then why not?