IMO, Cumbernauld takes too much flack on that account. In many ways, it represented the very best of the era's planning concepts/intentions - Of course there were flaws, poor quality system building in particular but many traditional communities in Scotland also suffered but the separation of people and cars, making it fully viable for public transport/foot/bike access throughout is of particular relevance today. The much maligned "centre" was planned to be a populated community in its own right and was amongst the first places to be planned with full disabled access but construction was halted after only about a third was built, then the cuts to/marginalisation of the new town development companies in the Tory years of the 1980s and their eventual disbanding under the Major government saw an entirely different planning ethos foisted on the place, which let-in the big commercial house builders to do whatever they liked and haphazard retail/business park planning that broke the place-up further.