Roundabouts are awesome --- self-organising, self-managing, power-free traffic junctions! But they do have a failure mode, which is that they tend to starve low-traffic loads if the traffic is too asymmetric.<p>For example: consider a T-junction with a roundabout at the junction. (Very common in the UK.) Most of the traffic is travelling across the T in a straight line. But I&#x27;m entering  the junction via the cross road.<p>The rules are that traffic from the driver side has priority over me, but that I have priority over traffic on the passenger side. So I stop at the line and wait for a gap.<p>With balanced traffic, I&#x27;ll be guaranteed a gap because the oncoming traffic will have to stop to wait for someone else, which means I can move onto the roundabout ahead of the vehicle they&#x27;re waiting for. But with unbalanced traffic, there won&#x27;t be a gap, and I&#x27;ll be stuck.<p>Typically what the traffic planners do at this point is add traffic lights, which is basically giving up, and defeats the whole point of having a roundabout in the first place.<p>...I used to live near this monstrosity, which had lights at every stop line. Blech. <a href="https:&#x2F;&#x2F;www.google.co.uk&#x2F;maps&#x2F;@51.436168,-0.8971696,200m&#x2F;data=!3m1!1e3" rel="nofollow">https:&#x2F;&#x2F;www.google.co.uk&#x2F;maps&#x2F;@51.436168,-0.8971696,200m&#x2F;dat...</a>