Richard J.:
Alstom have an alternative technology for 'heritage' streets which they
use in Bordeaux and elsewhere. This is APS ('alimentation par le sol'
or 'ground-supply') which is effectively a third rail set into the road
surface. It is made up of short sections, each of which is only
energised when the tram is over it.

This is the "stud" system that was tried in London and a number of
other places about 100 years ago. And the reason you've probably
never heard of it is that all too often the studs remained live when
the tram had moved on. One hopes that things are more reliable now.
--
Mark Brader "I like to think of [this] as self-explanatory."
Toronto "I hope *I* think of [it] that way."
-- Donald Westlake: "Trust Me On This"

My text in this article is in the public domain.