The Grange junction and Prince Albert Road are both closed by Guernsey Electricity for network upgrades.
From 13 March two key routes into southern and central St Peter Port will be closed for a number of weeks.
Vehicles won't be able to use the Grange, Doyle Road and Vauvert junction until 6 April.
It's to allow Guernsey Electricity to replace the existing low voltage pillar and street lighting in the area. More works on the infrastructure in the area are planned for later in April.
Prince Albert Road is currently closed for five weeks, until 19 April, as engineers for Guernsey Electricity upgrade high voltage cables in the road, and eventually integrate them with the new substation at the PEH.
Mike Lloyd, the Head of Distribution for Guernsey Electricity, says the work is necessary:
“These upgrades are essential to help us to continue providing a reliable and uninterrupted electricity supply to the area.
We would like to apologise in advance for any inconvenience this work may cause. Our teams will work hard to ensure the work is delivered within the times we have set out.”
Guernsey Electricity is undertaking a series of improvements across the island, funded by previous increases in tariffs, to ready the distribution network for the transition to greener energy.
This will see more people recharging cars and common household devices and also using small scale renewable like solar arrays.