{HEAD ~ The central version} of the road traffic control system maintains {TAIL ~ nonstop flow} of traffic on selected lanes of fastroads all the time by grouping the vehicles in closed columns in moving travel zones alternating with empty zones, marked by fixtures emitting zone marker signals controlled by central processor  
{ HEAD ~ The central version } of the road traffic control system maintains { TAIL ~ nonstop flow } of traffic on selected lanes of fastroads all the time by grouping the vehicles in closed columns in moving travel zones alternating with empty zones , marked by fixtures emitting zone marker signals controlled by central processor
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