Parts of three roads near Guernsey's airport have been closed for three-and-a-half weeks as part of a project to install a fibre optic internet network.
The work by JT and Sure sees Forest Road, Le Bourg and Rue des Landes shut for the first stage of a project to install cable ducting.
The Environment Department said the work would have a major impact on traffic and delays were inevitable.
It added that it and JT had done all they could to minimise disruption.
Local businesses near the airport said they were concerned about possible effects of the works.
Matthew Bateman, from Forest Stores, said: "They made some test holes by the airport, and we were roughly about 200 customers down while they did that."
The Environment Department said motorists were being advised to allow an extra half hour for their journeys.