There was a fad a couple of decades ago for "mini-roundabouts". They woud install these at junctions with a record of accidents. They were dirt-cheap, because t

There was a fad a couple of decades ago for "mini-roundabouts". They woud install these at junctions with a record of accidents. They were dirt-cheap, because they consisted of simply a couple of roundabout signs, and a circular bump about 6" high and a yard or so across, with smooth sides (i.e. no curb, you could easily drive straight over the bump). The rationale for these things was that they induce uncertainty in the driver, prompting him to slow down, pay more attention, and look more carefully. There are other schemes that were intended to induce uncertainty. The problem with all these schemes is that they depend on unfamiliarity to work; once a particular mini-roundabout is familiar, it no longer induces uncertainty. On the ring-road around my hometown, there is a series of "hamburger roundabouts". These are large, multilane roundabouts, with traffic-lights as well, and with a lane-pair that runs straight across the central circle, for through traffic. These configurations have never become at all familiar to me; they always induce uncertainty, and I hate them.