Do you mean this one?
Nope... that's not it either. The one I'm thinking of was aimed at residential streets.
Home Zone?
This was were I lived at the time (Hastings Rd) - the results were pretty good (admittedly one of the benefits was that most traffic diverted down the next non-HZ street) - it gave the street a very different ambience to the usual residential roadway (which essentially becomes a residents' car park with traffic cannonballing down the middle). That said it didn't suddenly become a utopia of skipping schoolchildren and garlanded street parties. Little steps. It wasn't that radical, I can't really see why it's not really caught on more.
I confess I've not visited in a while, so not sure what it looks like now. Certainly, south-east London could do with a dose of this.