Firefighters WERE tackling a blaze underneath the Tinsley Viaduct near the Meadowhall shopping centre in Sheffield last night.
South Yorkshire Fire and Rescue was called to the incident at around 7.20pm.
It is believed that the fire broke out after polystyrene plastic went up in flames underneath the viaduct, which carries the busy M1 motorway over the A631.
The fire service said one fire engine was dispatched to the scene.
The two-tier road bridge was the first of its kind in the UK.