I thought these were stylised trees, but the title of this installation under the motorway bridge carrying the M6 over the Lune Cycleway and the River Lune is self-explanatory: 'Where Traffic Cones Take Root'. It was designed by Mark Renn & Mick Thacker in 2000 as one of the public artworks in the Lune Millennium Park.
I believe it's supposed to be well-lit from within and to illuminate the entire 'cathedral-like' space, but I've frequently cycled past at night, and have yet to see more than a faint twinkle, as if of domestic christmas tree lights.