Police are appealing for information after the theft of machinery and equipment worth around £100,000.
The items were taken from a layby at Dalton on Tees, just off the A167 Darlington to Northallerton road.
The theft took place some time between the afternoon of Friday, 21 June, and the morning of Sunday 23 June.
Suspects cut a lock and chain from the compound gates to gain entry, and stole a low loader and its contents before making off.
The stolen low loader is a white King 28-tonne 3-axle low loader plus trailer, registration AT04 RST, with Eurovia written on the side.
The items on the low loader were also stolen, and include a white 50-tonne cement silo, an orange JCB GS2000 generator and a large white fuel tank containing red diesel.
The equipment, which was all new, has a total value of around £100,000.
The low loader would have been driven away, possibly in daylight hours, so officers are particularly keen to hear from anyone who may have relevant dashcam footage recorded in the area between Friday afternoon and Sunday morning.
PC Rob Davies, of North Yorkshire Police’s Rural Taskforce, said: “I am appealing for anyone who saw anything suspicious in the Dalton on Tees area around the time of the theft, or knows where the stolen equipment might be, to get in touch.”
Anyone with information should contact North Yorkshire Police on 101, quoting reference number 12190113472. Alternatively, contact Crimestoppers anonymously on 0800 555 111.
Following the theft, police are also urging people working at building and roadworks sites in North Yorkshire, particularly those in isolated areas, to check their security arrangements and be extra vigilant.
PC Davies added: “By their nature, building sites and compounds in rural areas are vulnerable and attractive targets for criminals.
“That means it’s really important to take extra security measures. Wherever possible, keep vehicles, plant and power tools in a secure and well-lit area, preferably a garage or outbuilding. Consider CCTV, fuel cap alarms, cages and other security measures.
“Even simple techniques like ‘defensive parking’ – parking vehicles against solid objects on the fuel tank side to prevent access – can have a strong deterrent effect.
“Also, get your property security-marked. Permanent marking, like a ‘dot peen’ mark, will deter thieves, as it makes the equipment far harder to sell on. It will also be much easier for us to return it to its rightful owner if it is lost or stolen, and could provide vital evidence to secure a prosecution.
“The equipment on building sites can be worth many thousands of pounds, which is why it’s so important to keep it safe. We want the message to go out to would-be thieves that targeting sites in rural areas of North Yorkshire is simply not worth the risk.”