Since the 1930’s, London and other cities in the UK used pedestrian guardrails. If you haven’t been there and seen them, here is a pretty good picture from the Daily Mail.
As you can see, in some places, they are on the sidewalk and line entire streets. In other places, they start about 100 feet before major intersections and then curve around the corner with 15 feet wide “holes” so that pedestrians are forced to use the crosswalks.
The idea was to separate the dangerous cars from the pedestrians, to keep pedestrians from crossing the street in the wrong places and to discourage illegal street parking because there was no access to the sidewalk.
Seemed like a good idea at the time, but, as usual, there were unintended consequences. I’ll let this newspaper article from The Times explain it.
The article is well written and explains the decades long, painful process that lead to the realization that more was not better. Millions of pounds are at stake. It will be very expensive to right decades of wrongs.
Removal is not without controversy. There is one fellow in particular, Douglas Stewart, who thinks that removal is an awful idea and offers his patented guard rail as an option.
You can read a good discussion paper here.
For the most part, US engineers realized the shortcomings of these railings and didn’t fall for their mystique. Too bad that they continue to adopt European ideas about sidepaths.