People who hog the middle lane on motorways or tailgate other drivers could be fined £100 if they are spotted by police.
Until now this type of careless driving has gone unpunished because it is difficult to take the cases to court. The authorities hope that on the spot penalties will be enough to encourage motorists to drive more considerately. Kate Bunkall has been looking at the problem.
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The RMT Union's comments come as it's announced a new operator will takeover the South West Trains franchise.
Monday's forecast for the west of the region
Monday's forecast for the east of the region