The incident occurred on Theobalds Lane, just off the A10 northbound, between 3.15pm and 3.25pm on Wednesday 1 March.
It is reported that several men were working on the waterways that run underneath the A10 when they were packing their kit into their van.
As they did so, a vehicle that has been described as a dark coloured or red SUV/people carrier was seen turning into the lane and back around as if to exit onto the A10.
The vehicle then stopped and a number of men exited, demanding that equipment was handed over before an altercation occurred.
It is alleged that one of the victims was then dragged along the A10 in front of incoming traffic as the suspects tried to escape in the vehicle.
A piece of surveying equipment, known as a Leica TS12 Total Station, was taken in its orange storage carry box, with a tripod stand.
PC Nina Garrard, who is investigating, said: “This was a terrifying incident, and our enquiries are continuing. As part of our investigation, we are appealing for anyone with information to please come forward.
“If you have a dash-cam fitted and were on the A10 at the time, please check it as you may have recorded some important footage that could help us. The A10 is a busy and fast-moving road so there may be several witnesses as a result.
“Additionally, if you see anyone trying to sell the surveying equipment either in person or online, please contact us. The serial number of the item is 235529.”
Anyone with information is asked to please email [email protected].
You can also report information online, speak to an operator in our Force Communications Room via our online web chat or call the non-emergency number 101, quoting crime reference 41/17412/23. Always dial 999 in an emergency.
Alternatively, you can stay 100% anonymous by contacting the independent charity Crimestoppers on 0800 555 111 or via their untraceable online form (opens in new window).