A Low Traffic Neighbourhood (LTN) is an area-wide intervention designed to reduce motor traffic levels across a series of streets, by confining through traffic to main roads (or 'boundary' roads).
Generally all the streets within a Low Traffic Neighbourhood will still be accessible to motor traffic, but the removal of through traffic means motor vehicle volumes will be substantially reduced across the entire Low Traffic Neighbourhood. Motor traffic on the streets in LTNs will only be accessing properties within it. The streets of successful LTNs will have sufficienlty low motor travel levels to be cycled or walked on by all potential users.
A street in a Low Traffic Neighbourhood in Waltham Forest
Low Traffic Neighbourhoods are created by the use of filtered permeability - measures which prevent motor traffic from travelling along a street, or through an area, while still permitting people to freely walk or cycle.
A frequent complaint is that Low Traffic Neighbourhoods merely displace motor traffic elsewhere - primarily onto the 'boundary' roads that border the scheme. It should be noted that these boundary roads are, or should be, more appropriate places for this motor traffic - they are the main roads which were historically designed as through routes, and will be wider and more direct than the smaller residential streets of the LTNs. Additionally any increase on main roads will be relatively negligible in the context of the volume of motor traffic that is already travelling on them.
And finally - and perhaps most importantly - the evidence suggests that any 'shifting' of motor traffic elsewhere is only a short-term phenomenon. As the LTN 'beds in' and people adapt to the new arrangements, journeys which were made by car are shifted to other modes - either because the car journey is now relatively inconvenient, or because walking and cycling is now safer and more attractive, or both. Evidence from Hackney even suggests that the implementation of LTNS doesn't lead to any rise in motor traffic levels on main roads at all.