The Transport Agency says changes are being made after a coroner's recommendations following the deaths of two Canadian tourist in Westland.
Part of the couple's vehicle - found in the Haast River. Photo: TV3
Connor Hayes, 25, and Joanna Lam, 24, died in September 2013 when falling debris from a storm swept their campervan off State Highway Six near Diana Falls and into the Haast River.
It had been decided to close the road but limited radio communication meant it took 90 minutes to happen.
By then the couple had already driven past the point where warning signs were due to be placed.
Coroner David Crerar said the New Zealand Transport Agency (NZTA) needed to enhance emergency procedures and contingency plans and ensure tourists were advised about hazardous conditions.
In his report he recommended that the agency ensure radio communication right along State Highway Six and install signs to update drivers about road conditions.
He also said gates should be put in place at the entrance and exit of the Haast Pass highway.
The ministry's group manager highways and network operations Tommy Parker said the repeater stations had been upgraded since the accident and more changes were being made.
Mr Parker said signs are being installed in April and gates are now in place to close the road if required.
The coroner found the couple died from multiple injuries, not drowning. Only Ms Lam's body has been recovered.