The title is misleading. The approach the council has taken is unlawful, not the Low Traffic Zone measures.
I don't know the exact details of this particular low traffic scheme, but a lot of them do feel an awful lot like
Fuck 'em, if we block cars then they will figure it out
While I want us to have a reduced reliance on cars, crossing your fingers and hoping other people will figure it out isn't really the best way for a council to act.
[Edit] So the ruling from the judge is just basically
Some people have concerns, and you didn't bother engaging them to show how they are wrong.
Considering that the top concern appear to be
- Displacement of Traffic onto Boundary Roads: Incremental traffic would be diverted onto already illegally polluted roads above World Health Organisation legal limits, such as the South Circular, and other surrounding roads, where over 6,300 children attend schools and nurseries—raising significant health and safety concerns for innocent and vulnerable communities (4).
It would be a good idea for the council to show that they have considered and communicated that they aren't planning on increasing traffic outside of schools to reduce the traffic in a residential street.