Scouted most of the 20 MPH zone in the centre of the city this evening, fixing the bus gate location and permitted traffic and doing a lot of s/^car=/motorcar=/g. So now applications like YOURS shouldn't route your car through the camera enforcement bit. Hopefully that link'll update nicely with the next planet.osm pull. Saved copy for comparison later on.

There's still no way of saying "PSVs only down this road, but bicycles and *only* bicycles may also use it between t₁ and t₂".