This was replaced with an electrically operated system controlled by an automatic fog detector in 1986.

It was the first toll road to put in fog detectors, automatic speed-limit reduction signs, noise controls and exclusive bus lanes.

There is second fog detector system mounted on the Fairway Buoy in Tees Bay outside the river entrance.

This tower houses a radar antennae, an automatic fog detector and a vertical set of four sectored red and white leading lights for navigation purposes.

'There's something strange going on and we're not getting any nearer, and look, there's some fog detectors clamped on the rail.'

This electric fog signal was connected to a fog detector which activated the fog signal if visibility fell below three nautical miles.

However, the complaints from the citizens of Trinidad Head were so vocal that the Coast Guard was forced to install the present ELG 300, operated by a fog detector.