[Symbiote]

It's called filtered permeability, and is a common retrofit in some countries in Europe. Wealth doesn't come into it — you will find it in some really poor parts of London, as well as the City (financial district) and some very rich neighbourhoods.

The point is that the non-arterial road can't handle the load, so the barrier returns it to its original purpose — the residents of and visitors to that street.

The intention is that the people who were using this route either - use the main road (slightly increasing the traffic there) - use public transport or a bicycle instead - stop making the journey altogether

https://en.wikipedia.org/wiki/Permeability_(spatial_and_tran...