For a permanent installation of seven LED steles on a grassy verge of the Mittlerer Ring, one of the busiest roads in Munich, a responsive, temporary artwork was developed based on the concept of translating kinetic energy into light. A cameratracking system registered each passing vehicle, which then triggered a wave of light on the steles. The waves followed the vehicles in realtime over a length of 70 metres between the first and the last stele. The light trails were cumulative, growing steadily brighter over the course of the day as the number of cars increased. A gentle haze of light in the morning became a bright storm of light by the time darkness descended on the city. Reactive Sparks was commissioned by Osram, Munich in 2008.