Holywell Hill will close to southbound traffic next week as maintenance work is conducted at the site.
The A5183 will be closed from The Peahen junction to Sumpter Yard, near The White Hart, from Monday (May 13) until next Friday (May 17).
Works will be carried out by Affinity Water, to improve the company's services.
A spokesperson for Affinity Water said: "We're currently carrying out essential maintenance in your area.
"This work is part of our ongoing efforts to improve our service to you.
SUGGESTED READING
"During these types of works, there may be some disruption to road users, please factor this into any journeys you make during this time."
Elsewhere, one lane will be closed on London Road from today (Tuesday, May 7) until Friday (May 10).
Temporary signals are also in use on Batchwood Drive and Harpenden Road.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here