Pedestrian guard rail (metal barriers between the pavement and the road) is almost entirely bad. It causes pedestrian congestion, makes drivers drive faster, forces peds off their desire lines and kills cyclists by trapping them against it every time they get left hooked. There's a good document on PGR by TFL.
Edinburgh has masses of pedestrian guard rail. Googling this I found that there was talk of removing lots of this back in 2012, there's a Scotsman article and some preliminary council policy.
Removing PGR is cheap (136 pounds for removing a section in London according to this FOI request).
Does anyone know what's going on with the council policy, whether there's a plan for reviewing and removing more PGR? Lesley Hinds spoke at a recent spokes meeting and suggested that the decision not to reinstate PGR on princes street after it was taken down for Hogmanay last year happened just because she suggested it to one of the neighbourhood teams, which seems to say that there's no systematic approach to this in the council.
Removal of PGR is surely the easiest and cheapest thing the council can do to improve our public space for pedestrians and cyclists, it would be great to accelerate things if we can.