All this month Hertfordshire Police are stepping up patrols on the county's roads in a crackdown on speeding.
They will be using marked cars, and speed guns to slow people down.
The force hopes seeing more police around will mean drivers think twice about breaking the limit.
This week alone they've caught more than 100 people speeding.
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After a dry start to the day, the cloud will thicken up from the west and rain will arrive later. Feeling cool with highs of 20ºC.
It will be a dry night with clear spells. Feeling a little cooler than recent nights. Dry at first tomorrow with rain arriving later.
GlaxoSmithKline is to invest £275 million in three sites including its operation at Ware in Hertfordshire.