Explained: The 'scary' radio takeover heard in Auckland tunnel

A Kiwi woman was "thrown off guard" when her radio was taken over by a "scary" robotic voice while driving through Auckland's Waterview Tunnel on Friday.

The student, who wished not to be named, was listening to the radio when the music was suddenly interrupted.

"As I entered the tunnel, there was a song playing on the radio, then it faded to static. The message started playing all the way through the tunnel."

She says she thought the robotic voice was going to make a nuclear bomb announcement.

"Attention. This is the control room. The tunnel is partially blocked," the voice says in a video posted to social media.

"Please proceed with caution, and maintain a safe following distance."

New Zealand Transport Agency system manager Andrea Williamson says the interference is called "radio re-broadcasting" and is common practice in tunnels overseas.

"Re-broadcasting means we can break into the radio broadcast with safety messages and instructions if there is an incident in the tunnel."

Vehicles lose their radio signal when they enter the Waterview Tunnel, which makes re-broadcasting possible.

"It provides a clear and effective way of communicating directly to motorists, which is why we encourage motorists to turn on their car radio if there is an incident in the tunnel."

Willamson says re-broadcasting is done sparingly and usually when a lane is blocked by a breakdown or a crash.

"It's designed for use if there is a fire or crash that would require evacuation of the tunnel, which hasn't been necessary in the two years the tunnel has been operating."

Despite the robotic voice warning of a blockage in the tunnel, the student, mentioned earlier, did not see anything while she was driving through.

"It was strange, because I didn't see any blockage. I thought it might have been a test."

Regardless of the reasonable explanation, she didn't enjoy her radio being taken over.

"I've talked to other people that heard it, and they thought it was cool. I thought it was scary," she says.

"I thought this kind of thing wasn't common in New Zealand, which is why it really scared me."

Willamson confirmed there was a vehicle breakdown in the tunnel on Friday, but was cleared quickly.

Newshub.