Deaths and serious injuries — the target of Vision Zero — are just the tip of a much larger iceberg of road danger harm. In addition to the 20 road traffic fatalities and 450 serious injuries in Oxford over the last decade, there were 2800 reported slight injuries (all of those from the STATS19 police database) and (for cycling injuries, across Oxfordshire) ten times as many hospital admissions and attendances (this includes non-collision injuries which are rarely reported to the police). And there will be many minor injuries and collisions which are neither reported to the police nor result in hospital presentations. (Following Ling Felce's death at the Plain, I heard several people make comments like "Oh yes, I've been knocked off my bike twice at the Plain" and "No, I didn't report it either time.") There are even more near-misses and other incidents perceived as threatening.
This level of road danger — anecdotal evidence suggests it is the high profile deaths and either the frequent near misses (for people who cycle) or injuries to friends and acquaintances (for people considering cycling, or cycling new routes) that have the most effect — means that perhaps two thirds of the people in Oxford either will not cycle at all or do so only in restricted places and times. (Chart 5 in the 2021 National Travel Attitudes Survey shows 75% of respondents reporting safety as a reason they either don't cycle or don't cycle more, while 65% of respondents to the Oxfordshire Cycle Survey - largely of people already cycling - ranked one or other safety issue as their major problem.) A smaller but significant number of people are deterred even from walking some trips, or letting their children walk them. For many people, road danger starts to constrain behaviour at levels not picked up at all by a narrow focus on "Killed and Seriously Injured" numbers — this is most obvious with parental concern about younger children, but also with older children, frailer adults, and women.
This in turn contributes to the 1 in 6 deaths in the UK — and a huge range of chronic health problems — that are attributable to physical inactivity. The bottom of the iceberg is enormous.