Traffic jams is a problem of urban areas to be specific about it...and not of the countryside... One dynamics that is involved is that people go to places where they need something or are needed to be...

A good way to prevent this is by scattering the areas of interest over a wider area. This way roads would not get congested from the volume of having too many vehicles wanting to go to the same destination.

Urban Zoning in its basic concept is a tool that can help in this regard. This solution is of course macro in scale and is (I believe) under the supervision and responsibility of city engineers and national (federal) builders.

In decentralization, the guiding concept is, the lesser people flock to urban areas, the lesser congestion is expected to happen.