The incident occurred between 9.05pm and 9.15pm on Thursday 6 April on the A146, near the Worlingham roundabout.
A motorist is alleged to have become angry with a traffic management worker regarding some diversions that had been put in place, before brandishing a knife at him.
The suspect was driving a red and black Renault Captur Iconic.
Police would like to hear from any potential witnesses to this incident, or anyone who was driving in the area and may have captured the incident on a dashcam.
Anyone with information about this incident is asked to contact Lowestoft Neighbourhood Response Team, quoting reference: 20023/23.
Website – www.suffolk.police.uk/contact-us/existing-report-update
Email – [email protected]
Phone – Call 101
Alternatively, contact the independent charity Crimestoppers 100% anonymously on 0800 555 111, or via their online form: www.crimestoppers-uk.org
Please note in the event of an emergency you should always call 999