It was being done outside peak times to lessen the effect on motorists, however travellers should plan for delays and consider using alternative routes, the agency said in a statement released this afternoon.
The agency apologised to motorists for any inconvenience and thanks motorists for their patience and understanding during the works.
For real time information on highway conditions and incidents visit www.nzta.govt.nz call 0800 4 HIGHWAYS or follow @nztawaibop on twitter.
For personalised information about driving conditions on their frequently used routes, motorists can check out and sign up to On The Move at www.onthemove.govt.nz.