Sundial by the M1 will be largest artwork in Britain

Chesterfield has a patchy record with tall, spiky structures.

Chesterfield has a patchy record with tall, spiky structures. A twist in the spire of its 800-year-old parish church became so pronounced last year that scientists who helped to stop the tilt of the leaning tower of Pisa were called in.

But with a confidence bordering on bravery, planners in the Derbyshire market town have granted approval to a spike like no other, which has acquired the sobriquet of "the tin wigwam" among residents.

It is the Solar Pyramid, a 132ft sundialto be built on a plinth by the M1 near the town. It will be the biggest piece of public art in the UK, knocking spots off Antony Gormley's 65ft Angel of the North near Gateshead, at a fraction of the price – £350,000 against the Angel's £800,000.

Its designers, the Derbyshire artists Richard Swain and Adam Walkden, yesterday proclaimed it a "fusion of art and science", designed to draw tourists to an area that has never made good the jobs lost when the coal and steel industries collapsed.

If sponsors are willing, their pyramid's three giant triangular sails of stainless steel will materialise next June on a small hill passed by 45,000 vehicles an hour at peak time. Shadows thrown by two of the sails will fall on the third, telling the time. Lights and lasers will enable the sculpture, inspired by a medieval observatory at Jaipur in India, to work in overcast conditions and at night.

An apprehensive RAC spokesman said the piece would be "fine in a gallery but not so good if you are travelling at 105ft per second in your Mondeo".