Both of those are great initiatives and we particularly support 20’s Plenty12 as a campaign that will bring real benefits to communities, pedestrians and children. However, 20mph speed limits on their own don’t improve safety for cycling, which still involves mixing with heavy traffic, as much as they do for walking or driving.13
Also, slow moving vehicles can be just as dangerous – a fifth of all cycling deaths in London in recent years were due to left-turning lorries.14 As with the roundabout example above, 20 mph roads aren’t particularly safe for slower riders such as children, older people, or those running errands or unsure of their route – they only really benefit fast-moving fitter cyclists who can keep up with traffic.
Strict liability – reversing the burden of proof when a vulnerable road user is injured on to the less vulnerable party – was only introduced in the Netherlands in 1992, long after deaths and injuries on the road started to fall, so it does not explain much of the safety effect seen there. And in some form or other it is widespread across Europe, yet nobody is arguing that it has made Italy’s roads, for example, much safer for cycling.15