The NZ Transport Agency (NZTA) awarded a $3million contract to Downer last year, for rock armouring work along 10 sites of Katiki Beach, between Shag Point and Moeraki, on State Highway1.
Rock armouring — the process of crushing and stockpiling rocks between tides — started earlier this month, and contractors would work on three different sites at the same time.
NZTA senior project manager Jason Forbes said rock armouring had never taken place along the whole beach, but it had been monitored since 1994.
"Most of Katiki Beach will eventually require some rock armouring, so coastal erosion doesn’t damage State Highway1, a critical road freight and lifeline link between Dunedin and Christchurch," Mr Forbes said.
"Realigning the highway would be very expensive, with rock armouring of the beach an affordable alternative."
Access to the work sites was restricted, however they were not easily accessible for the public anyway, he said.
In 1970, there were some erosion protection structures constructed, and in 2017 NZTA rock armoured a further three high-risk sites which were encroaching on State Highway 1.
The work was expected to be completed within the year, and there were traffic management measures in place to limit the impact on drivers.
"We thank the people for their patience and ask them to take care when driving through the work sites."
