COPENHAGEN — On a busy road in the center of town here, a string of green lights embedded in the bike path — the “Green Wave” — flashes on, helping cyclists avoid red traffic lights.

On a main artery into the city, truck drivers can see on smartphones when the next light will change. And in a nearby suburb, new LED streetlights brighten only as vehicles approach, dimming once they pass.

Aimed at saving money, cutting the use of fossil fuels and easing mobility, the installations are part of a growing wireless network of streetlamps and sensors that officials hope will help this city of roughly 1.2 million meet its ambitious goal of becoming the world’s first carbon-neutral capital by 2025.

Eventually, the network will serve other functions, like alerting the sanitation department to empty the trash cans and informing bikers of the quietest or fastest route to their destinations. It’s all made possible through an array of sensors embedded in the light fixtures that collect and feed data into software.

The system, still in its early stages, has put Copenhagen on the leading edge of a global race to use public outdoor lighting as the backbone of a vast sensory network capable of coordinating a raft of functions and services: whether easing traffic congestion, better predicting where to salt before a snowstorm or, to the alarm of privacy advocates, picking up on suspicious behavior on a busy street corner.

Cities worldwide are expected to replace 50 million aging fixtures with LEDs over the next three years, with roughly half of those in Europe. Some are mainly interested in switching from outmoded technologies to one that uses less energy and can last for decades. But many others want to take full advantage of the LED’s electronics, which are more conducive to wireless communication than other types of lighting.

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