They might not be nearly as bright as Melbourne's but the latest measure in Sydney to save people glued to their mobile phones from themselves is keeping the city in step with the times.

After a surge in pedestrian deaths last year, the switch has been flicked on the first in-ground lights to be installed in the central city at the intersections of Pitt and Goulburn streets, and Hay and Dixon streets.

The long strips of lights on either side of Hay Street near the inner west light rail line and Paddy's Market in Chinatown are larger than those at the intersection of Pitt and Goulburn streets.

The lights at both intersections are part of a trial announced by the state government last year to stop mobile-phone zombies from ignoring red signals and walking into oncoming traffic.