Every so often, a local council will recognise that allowing motorists unlimited used of local streets, regardless of whether they are local residents or just passing through, is a very expensive exercise. Contrary to popular belief, motorists do not "pay" for the road through registration and petrol tax. The bulk of registration fees are insurance premiums and the cost of administering the system. The cost of building and maintaining main roads comes from general revenue. In the case of local roads, it comes from the local ratepayers.
One way of lowering the maintenance burden is to cut down on the amount of traffic. The easiest way of doing that is to prevent "rat running". That is, allowing local residential streets to be used as thoroughfares by people who are just driving through the area.
Any suggestion is generally treated with the usual howls of protest, the loudest coming from people who do not use those local roads but feel a towering sense of entitlement to use them. After all, they "pay" for the roads, don't they? The howling is dressed up in other reasons such as; it will make other roads more congested, it will damage local businesses and the crowning turd in the cowpat - it will stop emergency services vehicles from getting through.
All complete nonsense of course.
In most areas, there is generally no designation between roads. The main difference between main arterial roads and residential streets is the width and the fact that the arterials have a 60 km/h speed limit while the residential streets have a (inappropriately high) 50 km/h speed limit. Other than that, anyone can use them as they wish.
You can see that in almost any suburb. This is a side street in Kilburn close to the corner of Regency and Churchill Road. I took this street at Random. It is Alabama Avenue and runs parallel to Churchill Road. After visiting Bunnings, I turned on it from Churchill Road to head east:
Here is the view looking back towards Churchill Road:
Here is the view towards Prospect Road at the other end:
You can see it is an invitation to all motorists to use it as an alternative to Regency Road. Nothing to slow you down except a couple of junctions. The signal is clear. This is space for cars with no obstacles to slow you down. You can speed through there with blinkers on. You would never believe this is a place where people live. All sense of neighbourhood is destroyed. Tragically, the two east-west streets either side are exactly the same.
This is a big problem right across Adelaide's suburbs. The street should be blocked to through traffic. Not just traffic-calmed with speed bumps. They make no difference to traffic levels. They merely provide a slight irritation for drivers and an even bigger one for anyone on a bicycle. The road should be blocked. It should be physically impossible for through traffic to be able to use it.
It is not hard to find somewhere that proves that blocking through traffic does not result in the sky caving in. This is a small part of Modbury Heights in the north east:
You can see that the streets inside the yellow coloured main roads are not open to through traffic. If for example you turn onto Minerva Crescent from Ladywood Drive, you very quickly end back there. There is no way to drive through to the other main roads. You have to use the main roads themselves to do that.
These neighbourhoods are doing ok. Emergency Services vehicles are getting through. Properly categorising streets by use can make a huge difference to local amenity. It is not the only thing of course. It should be part of a number of things done together to make our suburbs suitable for people rather than motor vehicles but it is a pretty easy one.