Centralised discussion space for TfL plans and cycling in London

It's just another bad design there, in a long history of bad designs dating back to the original filtering scheme in De Beauvoir. The following may sound too abstract, but I've said it many times. The problem is filtering at the edge of a traffic cell, i.e. at a junction with a cell boundary street. Southgate Road is such a cell boundary street, Northchurch Road a street inside two traffic cells, one east, one west of Southgate Road.

When you de-emphasise a side street entry, even with a showy design like this that supposedly makes it clear to drivers that they're meant to stop for east-west traffic, they will treat it as a street that they can speed past, and Southgate Road has long had a speeding issue. What you need is perfectly normal side street entries that cause normal driver behaviour--with give-way lines but always the possibility that another driver might turn out of or into these streets, which is what drivers are really worried about.

The previous design had a filter only on the east side, which caused numerous bad crashes as people emerged from Northchurch Road east effectively off a footway, even if a narrow cycle track is laid across the footway. Now someone has decided that what's really needed is to repeat this mistake on the other side and to de-emphasise the east-west crossing even more, with lots of lining and signing--forget that, it doesn't make much difference to driver behaviour. These designs are to be avoided.

The thing to understand about filters is that they do exactly the same job inside a traffic cell, ideally as close to the centre of a cell as possible, of deterring through motor traffic, as filters placed at the cell boundary, but do a far, far better job of enabling better junction designs on the cell boundary.