Photo/IllutrationThe Asahi Shimbun

Drivers will be warned when they are approaching expressway construction work areas via ultrasonic wave warning sounds in a system developed by a subsidiary of West Nippon Expressway Co. (NEXCO West Japan).

The system helps make drivers aware of lane closures even when they are not fully focused on the road due to drowsiness or other distractions. It also has the added benefit of the warning sounds being inaudible to residents living near expressways.

The subsidiary, based in Okinawa Prefecture, will introduce the system on the Okinawa Expressway on a full-fledged basis from mid-January.

Speakers about 130 centimeters high and 60 cm wide will be installed at intervals along expressways. They issue ultrasonic waves, which cannot be heard by humans due to high frequencies, toward the expressways.

When the ultrasonic waves hit windows and bodies of moving cars, the shapes of the waves change, enabling drivers to hear the sounds inside their vehicles. The speakers can send ultrasonic waves further than conventional speakers.

The subsidiary developed the system to prevent cars from running into construction work areas on expressways where some lanes are closed.

The warning sounds are said to be more effective at alerting drivers to construction work areas than electronic message boards or conventional signboards.

The subsidiary plans to use the system in a construction work area between Ginoza in Ginoza village and Kyoda in Nago city on Okinawa Expressway from mid-January to late March. It will also sell the system to other expressway operators from February.