Batteries from temporary traffic lights were stolen.
Between 5pm on January 10 and 8am on January 11, 12 batteries were removed from the temporary traffic lights in Cranborne Road.
Hertfordshire Constabulary are now investigating the thefts.
PC Paul Francis said: "The batteries are large and it would have taken the offender or offenders some time to load them onto a vehicle.
"I’m appealing for anyone who saw anything suspicious in the area between the times stated or noticed that the lights were not working to get in touch as you may have information that could assist our investigation."
Anyone with information is asked to contact PC Francis at paul.francis2@herts.pnn.police.uk, or by calling 101, quoting crime reference J3/18/62.
To give information anonymously, contact Crimestoppers on 0800 555 111.
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